ACUS01 KWNS 161958
SWODY1
SPC AC 161957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Sat Aug 16 2025

Valid 162000Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND
TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER
SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL...

...SUMMARY...
Scattered strong/severe thunderstorms are possible today into
tonight across parts of the northern Great Plains into the Midwest
and Great Lakes regions.

...20Z Update...
The prior forecast reasoning remains valid. Severe probabilities
were reduced in parts of northern/central Wisconsin where prior
convection has stabilized the boundary layer. Elsewhere, only minor
changes were made to the general thunderstorm forecast based on
current observational trends. See the previous discussion as well as
MCDs 1965/1966 for additional information.

..Wendt.. 08/16/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/

...Upper Midwest into the Mid MS Valley and Upper Great Lakes
Region...
An expansive MCS continues to move eastward across the Upper
Midwest, with a well-defined MCV evident in radar imagery over the
central WI/MN border vicinity. This MCS has continued to gradually
weaken throughout the morning, but a few strong updrafts persist
along its southeastern periphery over central WI. This portion of
the MCS is on the far northeastern periphery of the plume of steeper
mid-level lapse rates that extends from the northern/central High
Plains across the central Plains and into the Mid MS Valley. This
plume is observable in the 12Z sounding from DVN and ILX, which
sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km,
respectively. Dewpoints downstream across southern WI, northern IL,
and northern IN are in the low 70s, with upper 60s dewpoints also
covering much of southern Lower MI. The combination of ample
low-level moisture and steep mid-level lapse rates will result in
strong to very strong buoyancy to the south of the MCS from the
MN/IA border into northern/central IL.

Given the lack of a well-defined surface boundary and negligible
large-scale ascent, additional thunderstorm development will be
associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample
moisture and buoyancy downstream of the leading edge of the MCS
suggests the greater severe potential this afternoon/evening will
likely be associated with redevelopment/reintensification of the
MCS. Additionally, even if reintensification does not occur along
the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern
periphery of the MCV circulation as it moves into northern/central
WI. Increased severe-wind probabilities (i.e. 15%) were introduced
with this outlook to cover both of these potential scenarios. A
small 15% hail probability was introduce to cover potential for
later evening storms atop the outflow as well.

Storms are possible into northern IN and the Lower MI this afternoon
and evening as well, but the lower buoyancy should temper the
overall coverage and magnitude in these areas.

...SD and Vicinity...
A well-defined but rather weak shortwave trough is currently moving
through western CO/western WY, and will continue northeastward into
eastern WY/western Dakotas by this evening. Similar to yesterday,
high-based storms will develop ahead of the approaching shortwave
and intensify as they move eastward into a progressively more
moist/unstable air mass over west-central SD. Upscale growth into
another nocturnal MCS is forecast by most guidance, with the MCS
tracking northeastward across western/central SD tonight. Strong to
severe gusts are possible with this potential MCS across much of western/central SD.

$$

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ACUS01 KWNS 170051
SWODY1
SPC AC 170050

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 PM CDT Sat Aug 16 2025

Valid 170100Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN AND CENTRAL SOUTH DAKOTA AND SOUTHERN NORTH DAKOTA...

...SUMMARY...
A small organized cluster of thunderstorms with potential to produce
a swath of strong to severe wind gusts still appears possible across
parts of the central Dakotas later this evening into the overnight
hours. More sporadic strong thunderstorms with potential to produce
severe wind and hail are possible in a corridor across the Midwest
into Great Lakes vicinity.

...01Z Update...
In the wake of a weakening convective perturbation shifting
east-southeastward through the Great Lakes region, modest mid-level
height rises across eastern portions of the northern Great Plains
will gradually overspread the Upper Midwest and adjacent Great Lakes
region overnight. In the presence of weak and/or weakening
deep-layer shear, and weak mid/upper support for convective
development, the probabilities for the evolution of a sustained
organized severe storm cluster appear to be lowering. However, weak
low-level warm advection to the immediate cool side of convective
outflow, and a quasi-stationary frontal zone extending roughly from west-northwest of the Dubuque IA vicinity into the middle Missouri
Valley, is forecast to contribute to a corridor of increasing
thunderstorm development overnight. Although mid-level profiles
appear relatively warm, a plume of dry lower/mid-tropospheric air
with steep lapse rates may contribute to a risk for localized strong
wind gusts and some hail in sporadic stronger storms.

Upstream, across the middle Missouri Valley, as a weak mid-level
short wave trough slowly shifts eastward into the western Dakotas,
models continue to suggest that associated scattered thunderstorm
development may gradually consolidate into an organizing cluster,
perhaps aided by lift associated with warm advection on the nose of
a strengthening southerly low-level jet. As this occurs, although
deep-layer mean wind fields will remain generally weak, modest shear
and thermodynamic profiles with steep lower/mid-tropospheric lapse
rates and sizable CAPE may contribute to potential for the
development of strong to severe wind gusts overnight.

..Kerr.. 08/17/2025

$$

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ACUS01 KWNS 170550
SWODY1
SPC AC 170548

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Sun Aug 17 2025

Valid 171200Z - 181200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON INTO TONIGHT ACROSS PARTS OF THE NORTHERN
ROCKIES...PORTIONS OF THE MIDDLE MISSOURI VALLEY AND ADJACENT GREAT PLAINS...AND PARTS OF THE NORTHERN MID ATLANTIC...

...SUMMARY...
One or two clusters of thunderstorms may develop and gradually pose
a risk for strong to severe wind gusts across parts of the northern
Rockies into middle Missouri Valley late today into tonight. Strong thunderstorm development accompanied by potentially damaging wind
gusts is also possible across parts of the northern Mid Atlantic
late this afternoon and evening.

...Discussion...
Large-scale mid-level troughing is forecast to undergo further
amplification across southeastern Quebec through portions of
northern New England and the Canadian Maritimes during this period.
As this occurs, a notable cold front is forecast to advance
southward across much of the Northeast, Mid Atlantic and Ohio Valley
by 12Z Monday, beneath the northeastern periphery of large-scale
mid/upper ridging encompassing much of the interior U.S and southern
Canadian Provinces.

The western flank of the intrusion of cooler/drier boundary layer
air is likely to stall across the lower Ohio Valley into Upper
Midwest vicinity, but a more modest southward cool surge is also
forecast across the northern high plains, in the wake of weak
mid-level troughing slowly migrating within the larger-scale ridging
across and east of the Dakotas/Nebraska vicinity.

A number of other smaller-scale perturbations are forecast to
progress through modest/weak cyclonic to anticyclonic flow inland of
the Pacific coast through the Rockies, downstream of a significant,
amplifying large-scale trough offshore of the British Columbia and
Pacific Northwest coast.

...Parts of the mid Missouri Valley into Midwest...
Models indicate unsaturated lower/mid-tropospheric thermodynamic
profiles with steep lapse rates, aided by continuing eastward
advection of elevated mixed-layer air, will be maintained across
much of the South Dakota and Nebraska vicinity through this period.
Beneath this regime, seasonably high boundary-layer moisture content
will continue to contribute to the development of moderate to large
potential instability with insolation, along and south of an
initially stalled frontal zone across southern Minnesota/southern
Iowa through southern South Dakota.

Residual convection with a possible MCV may be in the process of
spreading well to the cool side of this boundary, across and
northeast of the eastern Dakotas at 12Z this morning. There appears
at least some potential for renewed convective development along the
southern flank of this activity, in closer proximity to the frontal
zone and destabilizing boundary-layer (roughly focused near the
Minnesota/Iowa border), aided by forcing for ascent associated with
warm advection during the day. Otherwise, stronger thunderstorm
development may await forcing associated with a perturbation within
the southern periphery of the weak mid-level troughing forecast to
overspread the (roughly) South Dakota/Nebraska border vicinity by
early this evening.

There is considerable spread evident among the models concerning
these and subsequent developments, with the NAM depicting the
evolution of a notable convective perturbation. Other output is
less pronounced, but, despite generally weak wind fields and shear,
forecast thermodynamic profiles appear potentially conducive to the
evolution of an upscale growing and organizing cluster with the
potential to produce strong to severe wind gusts this evening and
overnight.

...Montana...
Downstream of the northeastern Pacific mid-level trough, at least
broadly difluent upper flow, perhaps enhanced ahead of a subtle
mid-level wave crossing the northern Rockies, may aid the
development of thunderstorm activity off the mountains of south
central into southeastern Montana late this afternoon and evening.
Forecast soundings east of the higher terrain appear to include
sufficient shear and favorable thermodynamic profiles for the
evolution of a small east-southeastward propagating cluster with
potential to produce severe wind and hail.

...Northern Mid Atlantic...
Seasonably high moisture content and boundary-layer heating focused
along a pre-frontal surface trough may contribute to an environment
conducive to a few strong downbursts, aided by heavy precipitation
loading. It is possible that forcing for ascent associated with a
remnant convectively generated perturbation may contribute to a
clustering of thunderstorm activity along this corridor, from parts
of northern Virginia through southeastern Pennsylvania and New
Jersey, late this afternoon or evening.

..Kerr/Lyons.. 08/17/2025

$$

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ACUS01 KWNS 171221
SWODY1
SPC AC 171220

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0720 AM CDT Sun Aug 17 2025

Valid 171300Z - 181200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS...UPPER MIDWEST...MID ATLANTIC...AND SOUTHERN
NEW ENGLAND....

...SUMMARY...
One or two clusters of thunderstorms may develop and gradually pose
a risk for damaging wind gusts from the northern High Plains into
the Midwest this afternoon and tonight. Damaging thunderstorm wind
gusts may also occur across parts of the northern Mid Atlantic into
southern New England late this afternoon and evening.

...Northern Plains into Upper Midwest...
A broad upper ridge remains in place over southern/central U.S
today. Several weak perturbations will top the ridge during this
forecast period, affecting much of the northern Plains and upper
Midwest. Each of these smaller-scale shortwave troughs will
potentially be associated with a cluster of thunderstorms.
Sufficient low-level moisture and 25-35 knots of westerly flow aloft
pose some conditional risk of severe storms throughout this region,
but considerable uncertainty on the timing and placement of
convection precludes upgrading any areas to SLGT at this time.
Multiple areas of ongoing convection this morning further complicate
the forecast. Perhaps by 1630z, areas of stronger daytime heating/destabilization will allow better focus of the severe
outlook.

...Mid Atlantic into southern New England...
A cold front currently extends from OH northeastward into the St.
Lawrence Valley. Forecast soundings ahead of the front show weak
mid-level lapse rates and limited mid-level dry air. However,
strong heating into the 80s and 90s F, coupled with dewpoints near
70F will yield MLCAPE around 1000 J/kg. Sufficient westerly flow
aloft and frontal forcing may be sufficient for isolated strong
storms capable of locally gusty/damaging winds this afternoon.

..Hart/Dean.. 08/17/2025

$$

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ACUS01 KWNS 171632
SWODY1
SPC AC 171630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sun Aug 17 2025

Valid 171630Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE MIDDLE MISSOURI VALLEY VICINITY...

...SUMMARY...
One or two clusters of thunderstorms may develop and gradually pose
a risk for damaging wind gusts from the northern High Plains into
the Midwest this afternoon and tonight. Damaging thunderstorm wind
gusts may also occur across parts of the northern Mid Atlantic into
southern New England late this afternoon and evening.

...Northern/Central Plains into Upper Midwest...
The combination of close proximity to the upper ridge that covers
much of the central/southern CONUS, lack of more defined synoptic
features, and ample low-level moisture and buoyancy yields a complex
and uncertain forecast from the northern/central Plains into the
Midwest today and tonight. Recent satellite and radar imagery
depicts two MCVs across the region, one over central SD and the
other across central NE. Surface analysis also shows a low over the
central SD/NE border, along the northern periphery of the NE MCV. A
mix of convective outflow, cloud cover, and a formally more defined
surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these
features will likely play a role in thunderstorm development today.

The general expectation is for mesoscale ascent attendant to the
surface low and MCV to yield increasing thunderstorm development
across southeast SD and northeast NE over the next few hours. A
sharpening warm front will likely shift northward, providing a
favored corridor for storm progression, with the ongoing storms
continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk,
with severe coverage expected to become high enough to merit
introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over
central MN and central WI.

Much of the guidance also shows evening thunderstorm development
beginning in eastern WY/southwest SD/NE Panhandle region before then
spreading eastward/southeastward with time. This activity appears to
be initially associated with low-level convergence along the lee
troughing, with its progression southeastward likely tied to an
increasing low-level jet. Isolated hail is possible initially with a
few stronger gusts then possible overnight.

...Northern Rockies/northern High Plains...
Scattered high-based thunderstorms are expected this afternoon and
evening as ascent attendant the shortwave trough currently moving
through eastern OR spreads into the region. Combination of moderate
mid-level southwesterly flow, steep low-level lapse rates, and high
cloud bases could contribute to isolated strong to severe gusts
within these storms as they gradually move from southwest MT into central/southeastern MT.

...Mid Atlantic into southern New England...
Recent surface analysis places a cold front from northern ME
southwestward through western NY and northwest PA in northern OH.
Mid-level lapse rates are weak, and the relatively warm profiles
will likely limit buoyancy, despite dewpoints in the mid to upper
60s. However, strong heating into the 80s and 90s F and steep
low-level lapse rates combined with modest westerly flow aloft and
frontal forcing may be sufficient for isolated strong storms capable
of locally gusty/damaging winds this afternoon. Locally higher
probability for damaging gusts appears to exist across southern ME,
where greater deep-layer shear is presence, and over the northern
Mid-Atlantic where dewpoints and buoyancy will be highest.

..Mosier/Grams.. 08/17/2025

$$

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ACUS01 KWNS 172003
SWODY1
SPC AC 172001

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0301 PM CDT Sun Aug 17 2025

Valid 172000Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE MIDDLE MISSOURI VALLEY VICINITY...

...SUMMARY...
One or two clusters of thunderstorms may develop and gradually pose
a risk for damaging wind gusts from the northern High Plains into
the Midwest this afternoon and tonight. Damaging thunderstorm wind
gusts may also occur across parts of the northern Mid Atlantic into
southern New England late this afternoon and evening.

...20Z Update...
Preceding a remnant MCV tracking northeastward across parts of
southeastern SD, an elevated cluster of thunderstorms is spreading northeastward from east-central SD into southwest MN. Ahead of this
activity, earlier stable/billow clouds have eroded along/north of a
surface boundary draped across southwestern MN, where diurnal
heating amid lower 70s dewpoints is contributing to gradual air mass recovery/destabilization. Given this continued destabilization, the
Slight Risk was expanded slightly northward, and was also trimmed on
the western edge in the wake of the MCV.

Farther east, the Marginal Risk was expanded slightly westward into northeastern WV -- ahead of an ongoing cluster of thunderstorms with
a history of wind damage. See MCD 1975 for more details. For details
on the near-term severe threat over the Black Hills vicinity,
reference MCD 1976.

..Weinman.. 08/17/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 17 2025/

...Northern/Central Plains into Upper Midwest...
The combination of close proximity to the upper ridge that covers
much of the central/southern CONUS, lack of more defined synoptic
features, and ample low-level moisture and buoyancy yields a complex
and uncertain forecast from the northern/central Plains into the
Midwest today and tonight. Recent satellite and radar imagery
depicts two MCVs across the region, one over central SD and the
other across central NE. Surface analysis also shows a low over the
central SD/NE border, along the northern periphery of the NE MCV. A
mix of convective outflow, cloud cover, and a formally more defined
surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these
features will likely play a role in thunderstorm development today.

The general expectation is for mesoscale ascent attendant to the
surface low and MCV to yield increasing thunderstorm development
across southeast SD and northeast NE over the next few hours. A
sharpening warm front will likely shift northward, providing a
favored corridor for storm progression, with the ongoing storms
continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk,
with severe coverage expected to become high enough to merit
introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over
central MN and central WI.

Much of the guidance also shows evening thunderstorm development
beginning in eastern WY/southwest SD/NE Panhandle region before then
spreading eastward/southeastward with time. This activity appears to
be initially associated with low-level convergence along the lee
troughing, with its progression southeastward likely tied to an
increasing low-level jet. Isolated hail is possible initially with a
few stronger gusts then possible overnight.

...Northern Rockies/northern High Plains...
Scattered high-based thunderstorms are expected this afternoon and
evening as ascent attendant the shortwave trough currently moving
through eastern OR spreads into the region. Combination of moderate
mid-level southwesterly flow, steep low-level lapse rates, and high
cloud bases could contribute to isolated strong to severe gusts
within these storms as they gradually move from southwest MT into central/southeastern MT.

...Mid Atlantic into southern New England...
Recent surface analysis places a cold front from northern ME
southwestward through western NY and northwest PA in northern OH.
Mid-level lapse rates are weak, and the relatively warm profiles
will likely limit buoyancy, despite dewpoints in the mid to upper
60s. However, strong heating into the 80s and 90s F and steep
low-level lapse rates combined with modest westerly flow aloft and
frontal forcing may be sufficient for isolated strong storms capable
of locally gusty/damaging winds this afternoon. Locally higher
probability for damaging gusts appears to exist across southern ME,
where greater deep-layer shear is presence, and over the northern
Mid-Atlantic where dewpoints and buoyancy will be highest.

$$

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ACUS01 KWNS 180102
SWODY1
SPC AC 180100

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Sun Aug 17 2025

Valid 180100Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE CENTRAL/NORTHERN PLAINS AND UPPER MIDWEST...

...SUMMARY...
Scattered thunderstorms over the central and northern Plains may
pose a threat for damaging gusts and hail tonight, while a brief
tornado remains possible over the Midwest this evening.

...Central and northern Plains...
Weak ascent from a broad shortwave trough, visible in evening
water-vapor imagery, is supporting scattered thunderstorm
development across portions of western NE and SD this evening. Some
clustering of initial cells has been noted over the High Plains this
evening. Slight enhancement of southwesterly flow aloft attendant to
the broad shortwave trough suggests some upscale growth is possible
over southern SD and northern/central NE this evening into tonight.
Aided by and increasing southwesterly low-level jet, severe gusts
are possible over parts of NE and southern SD with a loosely
organized cluster/MCS progressing east/southestward.

Farther north along the front in the eastern Dakotas, scattered
storms remain possible tonight, especially as low-level mass
response increases at the nose of the low-level jet. Likely
elevated, sporadic hail and or isolated damaging winds would be
possible with any stronger clusters. Confidence in this scenario is
low owing the weak but persistent subsidence in the wake of the MCV
farther east.

...IA/MN...
Ahead of a diffuse MCV, scattered thunderstorms have developed along
an east-west oriented frontal zone. Along and south of this front,
very moist surface conditions are supporting large buoyancy. Area
VADs and forecast soundings show modest westerly flow aloft,
primarily along the cool side of the boundary. Still, slight
enhancement of low-level shear profiles and vertical vorticity along
the wind shift could support a brief supercell/tornado threat with
occasional stronger updrafts into this evening. With time, the
threat should begin to diminish later tonight as the boundary layer
begins to cool and the MCV continues eastward.

...Northern Rockies/northern High Plains...
Scattered high-based thunderstorms ongoing this evening should
continue into tonight as ascent attendant the shortwave trough over
the Northwest spreads eastward. Moderate southwesterly flow aloft,
and weak buoyancy atop steep low-level lapse rates will remain
supportive of isolated severe gusts with the stronger downdrafts.
The severe risk should steadily progress eastward into southeastern
MT and the far western Dakotas before weakening after sunset
tonight.

...Mid Atlantic...
Lingering scattered thunderstorms may pose a risk for a damaging
wind gust or two for a couple more hours this evening across
portions of the DelMarVa. While general convective trends continue
to suggest a decreasing threat with nocturnal stabilization
underway, a stray gust or two cannot be ruled out before storms off
shore tonight.

..Lyons.. 08/18/2025

$$

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ACUS01 KWNS 180549
SWODY1
SPC AC 180548

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Mon Aug 18 2025

Valid 181200Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL HIGH PLAINS...

...SUMMARY...
Strong to severe storms capable of damaging winds are possible in
parts of the Upper Midwest today. Isolated to widely scattered
storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight.

...Central High Plains...
A broad upper trough over the northern Plains will move east today
with an attendant surface low and cold front also moving east.
Behind the departing surface low, weak upslope flow is expected
across portions of western SD, northeastern WY. Strong heating and
steep mid-level lapse rates should allow for diurnal destabilization
with widely scattered thunderstorms expected along a lee trough by
the afternoon. Elongated hodographs, courtesy of 30-40 kt of
westerly flow aloft, will allow for some organized storms including
supercells or clusters. Steep mid-level lapse rates, and moderate
buoyancy will support a hail risk.

Farther south, stronger heating and mixing will limit low-level
moisture across southeastern WY and northeastern CO. Still, enough
CAPE should be present for scattered high-based storms near peak
heating. The steep low-level lapse rates and any clustering that
develops should support damaging winds as storms spread eastward
into northeast CO and western NE.

Some potential exists for a longer-lived cluster to spread eastward
into central/eastern NE and northern KS overnight. Should this
occur, damaging winds and some hail would be the primary concerns,
though this scenario remains highly uncertain given weaker forecast
low-level jet.

...Midwest...
One or more clusters of thunderstorms or an MCV is expected to be
ongoing at the start of the period in the vicinity of the warm front
across portions of IA/MN, casting significant uncertainty on the
overall convective evolution for the day. Filtered diurnal heating
and nebulous ascent from the broad trough over the northern Plains
could support continuation of these storms and additional
development into southern WI and northern IL this afternoon. While complications abound, substantial buoyancy (3000-4000 J/kg of
MLCAPE) and dewpoints in the mid 70s F south of the composite
front/remnant outflow will be supportive of occasional vigorous
updrafts. Modest enhancement of the mid and upper-level flow could
support a few semi-organized clusters or transient supercells with
damaging wind potential. Given the potential for outflow or
thunderstorm clusters to significantly alter the environment,
confidence in higher wind probabilities is low.

...Southwest into central Montana...
Despite a strong ridge building into the northern Rockies,
sufficient moisture may promote thunderstorm development in the
higher terrain this afternoon. 20-30 kt of flow aloft will be
sufficient to support at least marginally organized storms. However,
strong mixing during the afternoon could limit buoyancy and storm
coverage. Occasional strong, gusty outflow winds are possible with
any high-based storms, but confidence in severe potential remains
low.

..Lyons/Kerr.. 08/18/2025

$$

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ACUS01 KWNS 181236
SWODY1
SPC AC 181235

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0735 AM CDT Mon Aug 18 2025

Valid 181300Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL/NORTHERN PLAINS...AND OVER PARTS OF THE MIDWEST....

...SUMMARY...
Strong to severe storms capable of damaging winds are possible in
parts of the Midwest today. Widely scattered storms with large hail
and severe winds are possible in parts of the central/northern
Plains through tonight.

...IA/WI/IL...
A long-lived MCS continues to track eastward across central IA this
morning. Visible satellite imagery shows the potential for
considerable daytime heating ahead of this activity across parts of
eastern IA/southern WI/northern IL, where temperatures will warm
into the 90s. Ample low-level moisture will yield afternoon MLCAPE
values around 3000 J/kg, along with sufficient westerly flow aloft
for some convective organization. It is unclear whether current
activity will intensify, or new storms will form later today.
Regardless, this region will see the potential for strong/severe
storms capable of damaging wind gusts. A tornado or two is also
possible, given the backed low-level winds and east-west baroclinic
zone along the WI/IL border. Have added a SLGT risk for this
scenario.

...Northeast CO into SD/NE/KS...
Strong heating and ample low/mid level moisture will promote the
development of scattered thunderstorms by mid-afternoon over the
foothills and plains of central/eastern CO. Other more isolated
storms are expected farther north across western NE into the Black
Hills region. All of these storms will be relatively high-based,
posing a risk of damaging wind gusts. Sufficient westerly flow will
also aid in a few transient supercells capable of large hail. These
storms may persist into the evening, tracking into central NE before
weakening.

...MO/AR...
Clear skies are evident this morning across central/southern MO and
much of AR. Hot and humid conditions will ensue with temperatures
reaching the upper 90s. Most CAM solutions suggest widely scattered
afternoon thunderstorm development in this environment of steep
low-level lapse rates and 1500-2000 J/kg of MLCAPE. The strongest
storms will be capable of locally damaging wind gusts.

..Hart/Dean.. 08/18/2025

$$

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ACUS01 KWNS 181630
SWODY1
SPC AC 181629

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Mon Aug 18 2025

Valid 181630Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN WI
AND NORTHERN IL...AND ACROSS PORTIONS OF THE NORTHERN AND CENTRAL
PLAINS...

...SUMMARY...
Strong to severe storms capable of damaging winds are possible in
parts of the Midwest today. Widely scattered storms with large hail
and severe winds are possible in parts of the central/northern
Plains through tonight.

...Mid MS Valley...
Extensive outflow from last night's MCS currently extends from
extreme southwest WI southwestward through eastern IA and
north-central MO into eastern KS. This outflow has been moving
quickly eastward/southeastward this morning, and this trend is
expected to continue, although some slowing of its progression speed
is possible over time. The downstream airmass across from southern
WI and IL is characterized by dewpoints in the low to mid 70s.
Mid-level lapse rates are generally poor across the region, but
heating of this very moist airmass will still result in strong to
very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late
afternoon.

Strong to severe storms are possible along this outflow as it
impinges on this moist and buoyant airmass. Current trends suggest
the greatest severe potential will exist this afternoon across
southern WI and northern IL, where slightly stronger mid-level flow,
backed surface winds, and an east-west baroclinic zone exists.
Recently issued MCD 1983 addresses the short-term severe potential
for this area.

...Central High Plains into the northern/central Plains...
Strong heating and ample low/mid level moisture will promote the
development of scattered thunderstorms by mid-afternoon over the
foothills and plains of central/eastern CO. Additional isolated
storms are possible farther north across western NE into the Black
Hills region. Much of this area is within a corridor of modest
mid-level flow on the northern periphery of the upper ridging
covering the southern CONUS. Resulting modest shear may be enough
for hail production with the initial development before these
high-based storms trend towards outflow-dominant structures with
time. These storms may persist into the evening, with an attendant
threat for strong to severe gusts progressing into central NE before
weakening.

...MO/AR...
Clear skies and strong diurnal heating are expected across
central/southern MO and much of AR. Temperatures in the upper 90s
are expected, with dewpoints remaining in the mid 60s despite strong
mixing. These hot and humid conditions will result in strong
buoyancy this afternoon, with most guidance suggesting MLCAPE around
2000 J/kg. Shear will be weak, yielding mostly disorganized
multicells, but the strongest storms will be capable of locally
damaging wind gusts.

..Mosier/Wendt.. 08/18/2025

$$

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ACUS01 KWNS 182000
SWODY1
SPC AC 181959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Mon Aug 18 2025

Valid 182000Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS...

...SUMMARY...
Strong to severe storms capable of damaging winds are possible in
parts of the Midwest today. Widely scattered storms with large hail
and severe winds are possible in parts of the central/northern
Plains through tonight.

...20Z Update...
The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the
passage of an MCS has resulted in low-level stabilization.
Otherwise, only minor changes was made to severe/thunder
probabilities to reflect the latest guidance and observations.

..Squitieri.. 08/18/2025

.PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/

...Mid MS Valley...
Extensive outflow from last night's MCS currently extends from
extreme southwest WI southwestward through eastern IA and
north-central MO into eastern KS. This outflow has been moving
quickly eastward/southeastward this morning, and this trend is
expected to continue, although some slowing of its progression speed
is possible over time. The downstream airmass across from southern
WI and IL is characterized by dewpoints in the low to mid 70s.
Mid-level lapse rates are generally poor across the region, but
heating of this very moist airmass will still result in strong to
very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late
afternoon.

Strong to severe storms are possible along this outflow as it
impinges on this moist and buoyant airmass. Current trends suggest
the greatest severe potential will exist this afternoon across
southern WI and northern IL, where slightly stronger mid-level flow,
backed surface winds, and an east-west baroclinic zone exists.
Recently issued MCD 1983 addresses the short-term severe potential
for this area.

...Central High Plains into the northern/central Plains...
Strong heating and ample low/mid level moisture will promote the
development of scattered thunderstorms by mid-afternoon over the
foothills and plains of central/eastern CO. Additional isolated
storms are possible farther north across western NE into the Black
Hills region. Much of this area is within a corridor of modest
mid-level flow on the northern periphery of the upper ridging
covering the southern CONUS. Resulting modest shear may be enough
for hail production with the initial development before these
high-based storms trend towards outflow-dominant structures with
time. These storms may persist into the evening, with an attendant
threat for strong to severe gusts progressing into central NE before
weakening.

...MO/AR...
Clear skies and strong diurnal heating are expected across
central/southern MO and much of AR. Temperatures in the upper 90s
are expected, with dewpoints remaining in the mid 60s despite strong
mixing. These hot and humid conditions will result in strong
buoyancy this afternoon, with most guidance suggesting MLCAPE around
2000 J/kg. Shear will be weak, yielding mostly disorganized
multicells, but the strongest storms will be capable of locally
damaging wind gusts.

$$

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ACUS01 KWNS 190051
SWODY1
SPC AC 190049

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 PM CDT Mon Aug 18 2025

Valid 190100Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING
ACROSS PARTS OF NORTHERN KANSAS AND SOUTHERN NEBRASKA...AND PARTS OF
SOUTH CENTRAL SOUTH DAKOTA...

...SUMMARY...
A clustering of storms may continue to generate strong to severe
wind gusts across parts of the central Great Plains through much of
the evening.

...01Z Update...

...Central Great Plains...
A low-level convergence zone has become a focus for thunderstorm
development near/north of the I-70 corridor of western Kansas, with
additional thunderstorm activity approaching the eastern Colorado
state border vicinity, aided by a weak short wave impulse
progressing around the northeastern periphery of a prominent
mid-level high centered east of the Four Corners. This activity,
and associated convective outflow, may continue to gradually
consolidate into a further enlarging convective cluster, which could
eventually generate a notable mesoscale convective vortex while
propagating slowly eastward within otherwise light westerly
deep-layer mean flow across the central Great Plains.

A deeply mixed boundary-layer across the high plains has contributed
to an environment conducive to downbursts and surface cold pool
development. As the cold pools consolidate and spread into a much
more moist boundary layer with large potential instability across
south central Nebraska/central Kansas, it is possible that forcing
for ascent may overcome increasing inhibition associated with
boundary layer cooling, and maintain vigorous convective development
into and through the overnight hours.

...Dakotas...
Widely scattered strong boundary-layer based thunderstorm
development is generally expected to wane over the next few hours,
as mid-level inhibition increases with the loss of daytime heating.

..Kerr.. 08/19/2025

$$

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ACUS01 KWNS 190537
SWODY1
SPC AC 190535

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1235 AM CDT Tue Aug 19 2025

Valid 191200Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING ACROSS PARTS OF THE CENTRAL GREAT PLAINS AND OZARK
PLATEAU INTO OHIO VALLEY...AND THIS EVENING INTO THE OVERNIGHT HOURS
ACROSS PARTS OF WESTERN MONTANA...

...SUMMARY...
Scattered strong thunderstorm activity may impact a corridor from
the central Great Plains into the Ohio Valley this afternoon and
evening, accompanied by locally strong to severe wind gusts. A
cluster of thunderstorms may also develop across and northeast of
the mountains of western Montana accompanied by strong to severe
wind gusts this evening into the overnight hours.

...Discussion...
Models indicate that a prominent mid/upper high centered near/east
of the Four Corners will be maintained through this period. To the
north of this circulation, heights are forecast to build through the
day along a broad axis extending north-northeastward into the
eastern Canadian Prairies, ahead of a fairly vigorous low and south-southwestward trailing troughing migrating inland of the
British Columbia/Pacific Northwest coast.

Downstream, to the south of the stronger westerlies, it appears that
weak mid-level troughing will dig across and southeast of the Great
Lakes region, perhaps suppressing mid-level heights across parts of
the northern Mid Atlantic into southern Appalachians by 12Z
Wednesday, to the northwest of Hurricane Erin as it continues a slow north-northwestward migration to the east/northeast of the Bahamas.
On the trailing, southwestern flank of this troughing, a remnant
convectively enhanced perturbation initially across Kansas may
slowly dig southward toward the southern Great Plains Red River
vicinity.

In lower levels, a weak surface low is forecast to slowly progress
across southern portions of the Great Lakes region, with a weak
trailing surface front, reinforced in segments by convective
outflow, advancing southward into the Ohio Valley, Mid South and Red
River Valley by late tonight.

...Central Great Plains into Ohio Valley...
Seasonably high boundary-layer moisture content along/ahead of the
southward advancing front is forecast to contribute to the
development of moderate to strong potential instability with daytime
heating, beneath a residual plume of relatively steep
lower/mid-tropospheric lapse rates, particularly across parts of the
central Great Plains into Ozark Plateau. Coincident with and
subsequent to peak boundary-layer destabilization, weak mid-level
height falls may contribute to considerable upscale growing
thunderstorm development during the mid to late afternoon and
evening. Although rather weak deep-layer mean wind fields and shear
are likely to limit the risk for organized severe convection,
thermodynamic profiles may still be conducive to localized
downbursts in stronger storms, and gusty winds occasionally
approaching severe limits along consolidating and strengthening
southward propagating cold pools into this evening.

...Northern Rockies...
Although the time of arrival of mid-level height falls/forcing for
ascent downstream of the inland progressing mid-level troughing may
be sometime this evening, it appears that this will be preceded by
sufficient moistening in the presence of steep lapse rates to
support thunderstorm development. Models suggest that convection
will initiate across the mountains of western Montana this evening,
before consolidating and spreading in a cluster east of the higher
terrain through north central Montana overnight. Given
west-southwesterly mean flow strengthening to 30-40+ kt in the
cloud-bearing layer, and a residual deep sub-cloud mixed-layer,
there may be sufficient downward mixing of momentum to contribute to
a few strong to severe surface gusts.

..Kerr/Lyons.. 08/19/2025

$$

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ACUS01 KWNS 191255
SWODY1
SPC AC 191253

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Tue Aug 19 2025

Valid 191300Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS AND OZARKS TO OHIO VALLEY AND NORTHERN
ROCKIES...

...SUMMARY...
Scattered strong to severe thunderstorms capable of damaging winds
will be possible across the south-central Great Plains and Ozarks to
the Ohio Valley this afternoon and evening. Isolated severe
thunderstorms may also occur across parts of the northern Rockies
including western and northern Montana.

...South-central Plains and Ozarks to Ohio Valley...
Outside of a few areas of lingering early day convection/small-scale
outflows, a hot air mass and relatively high moisture content will
reside to the south of a synoptic front extending from the
south-central Plains to the Midwest/Ohio Valley. Moderate to strong
buoyancy with daytime heating, beneath a residual plume of
relatively steep lower/mid-tropospheric lapse rates, will exist
particularly across parts of the south-central Plains to Ozark
Plateau, including parts of Kansas/Oklahoma to Arkansas/southern
Missouri. As storms diurnally develop/increase, upscale-growing
thunderstorm development should occur during the mid to late
afternoon and early evening. While weak deep-layer winds and shear
are likely to limit the risk for organized severe convection,
thermodynamic profiles will be conducive for downbursts and
severe-caliber wind gusts with the stronger storms, particularly
this afternoon through around sunset.

...Northern Rockies including western/northern Montana...
The late-day arrival of weak height falls and approaching mid-level perturbation should influence isolated thunderstorm development late
this afternoon, and more so into this evening, across parts of
northern Idaho in western and eventually northern Montana.
Sufficient moisture/buoyancy near and behind a surface front, along
with strengthening flow aloft, will support the possibility of some
severe storms, and potentially some clustering/organization to the
storms as they progress across western/northern Montana.
West-southwesterly mean flow strengthening to 30-40+ kt in the
cloud-bearing layer, and a residual deep sub-cloud mixed-layer, will
likely be sufficient for downward mixing of momentum to contribute
to a few strong to severe wind gusts.

..Guyer/Dean.. 08/19/2025

$$

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ACUS01 KWNS 191629
SWODY1
SPC AC 191628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Tue Aug 19 2025

Valid 191630Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO VALLEY TO THE SOUTHERN/CENTRAL PLAINS...AND OVER PORTIONS
OF WESTERN/NORTHERN MONTANA...

...SUMMARY...
Scattered thunderstorms capable of producing occasional damaging
winds will be possible across parts of the south-central Plains and
Ozarks to the Ohio Valley this afternoon and evening. Isolated
severe thunderstorms may also occur this evening across parts of
western and northern Montana.

...Ohio Valley to the Central/Southern Plains...
Upper ridging will remain prominent today across the Southwest and southern/central Rockies, as a weak mid/upper-level trough moves east-southeastward across the Great Lakes and OH Valley regions. At
the surface, a weak cold front is forecast to advance
east-southeastward across parts of the OH Valley and mid MS Valley
today, and more slowly southward over portions of the
central/southern Plains while weakening. This boundary should aid in
at least scattered thunderstorm development through the afternoon as
diurnal heating of a moist airmass along/south of the front occurs.
While deep-layer flow and related shear are expected to remain
generally weak, moderate to strong instability and the steepening of
low-level lapse rates may support occasional strong to damaging
winds with water-loaded downdrafts within the stronger cores. Only
minor adjustments have been made to the broad Marginal Risk based on
latest observational and short-term guidance trends.

...Northern Rockies/High Plains...
An embedded mid-level shortwave trough will advance northeastward
this evening and overnight across parts of the northern Rockies and
adjacent High Plains on the western to northern periphery of
prominent upper ridging over the Southwest. Isolated to perhaps
widely scattered thunderstorms should develop through the evening
hours across parts of western MT and vicinity as large-scale ascent
associated with the shortwave trough overspreads the northern
Rockies. Instability is forecast to remain rather limited, but
steepened lapse rates aloft and a well-mixed boundary layer could
still aid in some convective downdraft enhancement, with isolated
strong to severe gusts possible as convection spreads northeastward
towards the international border.

...Coastal Texas...
A weak mid-level perturbation with ongoing thunderstorms along parts
of the middle TX Coast should continue south-southwestward this
afternoon and evening. Low/mid-level flow should remain modest,
which will generally limit thunderstorm organization. Still, some
clustering could support isolated strong/gusty winds in the presence
of increasing instability this afternoon across parts of
south-central TX and the lower TX Coast. Confidence in
severe-caliber gusts remains too low to include any severe
probabilities at this time.

..Gleason/Wendt.. 08/19/2025

$$

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ACUS01 KWNS 191948
SWODY1
SPC AC 191947

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0247 PM CDT Tue Aug 19 2025

Valid 192000Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO VALLEY TO THE SOUTHERN/CENTRAL PLAINS AND OVER PORTIONS OF WESTERN/NORTHERN MONTANA...

...SUMMARY...
Scattered thunderstorms capable of producing occasional damaging
winds will be possible across parts of the south-central Plains and
Ozarks to the Ohio Valley this afternoon and evening. Isolated
severe thunderstorms may also occur this evening across parts of
western and northern Montana.

...20z Update...
The Marginal Risk was trimmed across northern/east-central Kansas
into southern Missouri. Morning convection associated with a remnant
MCV has diminished, with more stable near surface conditions in it's
wake. Visible satellite shows decreasing cloud cover and dew points
lowering amid warming and mixing. CAM guidance shows low potential
for some redevelopment of thunderstorm activity along the front
later in the evening. Some portion on the Marginal was left across
southern Missouri to account for this risk.

Otherwise, the outlook remains on track. See previous discussion
below for more information.

..Thornton.. 08/19/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Tue Aug 19 2025/

...Ohio Valley to the Central/Southern Plains...
Upper ridging will remain prominent today across the Southwest and southern/central Rockies, as a weak mid/upper-level trough moves east-southeastward across the Great Lakes and OH Valley regions. At
the surface, a weak cold front is forecast to advance
east-southeastward across parts of the OH Valley and mid MS Valley
today, and more slowly southward over portions of the
central/southern Plains while weakening. This boundary should aid in
at least scattered thunderstorm development through the afternoon as
diurnal heating of a moist airmass along/south of the front occurs.
While deep-layer flow and related shear are expected to remain
generally weak, moderate to strong instability and the steepening of
low-level lapse rates may support occasional strong to damaging
winds with water-loaded downdrafts within the stronger cores. Only
minor adjustments have been made to the broad Marginal Risk based on
latest observational and short-term guidance trends.

...Northern Rockies/High Plains...
An embedded mid-level shortwave trough will advance northeastward
this evening and overnight across parts of the northern Rockies and
adjacent High Plains on the western to northern periphery of
prominent upper ridging over the Southwest. Isolated to perhaps
widely scattered thunderstorms should develop through the evening
hours across parts of western MT and vicinity as large-scale ascent
associated with the shortwave trough overspreads the northern
Rockies. Instability is forecast to remain rather limited, but
steepened lapse rates aloft and a well-mixed boundary layer could
still aid in some convective downdraft enhancement, with isolated
strong to severe gusts possible as convection spreads northeastward
towards the international border.

...Coastal Texas...
A weak mid-level perturbation with ongoing thunderstorms along parts
of the middle TX Coast should continue south-southwestward this
afternoon and evening. Low/mid-level flow should remain modest,
which will generally limit thunderstorm organization. Still, some
clustering could support isolated strong/gusty winds in the presence
of increasing instability this afternoon across parts of
south-central TX and the lower TX Coast. Confidence in
severe-caliber gusts remains too low to include any severe
probabilities at this time.

$$

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ACUS01 KWNS 200032
SWODY1
SPC AC 200031

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0731 PM CDT Tue Aug 19 2025

Valid 200100Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS EVENING
INTO THE OVERNIGHT HOURS ACROSS PARTS OF WESTERN INTO NORTH CENTRAL
MONTANA...

...SUMMARY...
Strong to severe wind gusts may develop with a consolidating cluster
of thunderstorms across western through north central Montana this
evening into the overnight hours.

...01Z Update...

...Northern Rockies...
Thunderstorms have begun to initiate across the Bitterroots
vicinity, with deepening convection also evident to the lee of the
mountains of western Montana, between Great Falls and Cut Bank.
Although the hot and deeply mixed boundary layer which has evolved
across the region appears only characterized by weak CAPE, models
suggest that mid-level forcing for ascent overspreading the region
will probably become supportive of a consolidating cluster, in the
presence of cloud-bearing layer mean flow strengthening to 30-40+
kt. Even with onset of boundary-layer cooling within the next
couple of hours, sub-cloud thermodynamic profiles will remain
conducive to strengthening downward momentum transfer accompanied by
surface gusts approaching or exceeding severe limits. As convection
approaches better boundary-layer moisture across the Havre vicinity
by late evening, more unstable updraft inflow might support further intensification of thunderstorms before spreading across the
international border.

..Kerr.. 08/20/2025

$$

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ACUS01 KWNS 200536
SWODY1
SPC AC 200534

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1234 AM CDT Wed Aug 20 2025

Valid 201200Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY ACROSS THE
WESTERN AND CENTRAL GULF COAST STATES AND THE INTERNATIONAL BORDER
VICINITY OF NORTH DAKOTA...

...SUMMARY...
Scattered thunderstorms developing this afternoon and evening across
the western and central Gulf Coast states may pose a risk for
localized potentially damaging wind gusts. Otherwise, there appears
some risk for an isolated severe thunderstorm or two across parts of
northern North Dakota.

...Discussion...
Models indicate that a prominent mid/upper high will be maintained
over the Four Corners vicinity through this period. However,
initially amplified ridging extending to its north, as far as the
Canadian Prairies, appears likely to become suppressed southeastward
toward the central international border vicinity, as a significant
short wave perturbation progresses east of the Canadian Rockies into
Prairies by late tonight. It appears that this may be accompanied
by weak cyclogenesis across southern Saskatchewan toward the central Saskatchewan/Manitoba border vicinity, with a trailing cold front
advancing across the Montana international border by late tonight.

At the same time, an increasingly sheared perturbation will continue progressing through weak larger-scale mid-level troughing digging
across the Northeast, and southeastward around the periphery of the
high, across the Ohio/Tennessee Valleys and southern Great Plains.
To the southeast of this feature, Hurricane Erin is forecast to turn
slowly north-northeastward, offshore of the southern through middle
Atlantic Seaboard.

...Gulf Coast States...
A diffuse surface frontal zone, reinforced in segments by convective
outflow, will continue slowly southward ahead of the mid-level shear
axis, likely reaching portions of central Texas through Louisiana
and central/northern Mississippi and Alabama by mid to late
afternoon. Along and ahead of this front, a corridor of stronger
heating of a seasonably moist boundary layer, perhaps still
coincident with a residual plume of relatively steep
lower/mid-tropospheric lapse rates, may continue to contribute to
thermodynamic profiles supportive of localized downbursts and gusty
winds on convectively generated surface cold pools. It is not clear
that the severe threat will be any more widespread than the sparse
coverage of preceding days, but it may perhaps be marginally
sufficient to justify 5 percent severe wind probabilities.

...North Dakota...
Models indicate that a narrow corridor of moderate to large
potential instability may develop along/ahead of the surface cold
front, a pre-frontal surface trough and developing warm frontal zone
across parts of the Dakotas into eastern Saskatchewan by late this
afternoon. However, beneath the nose of a plume of warm and capping
elevated mixed-layer air, mid/upper support for the initiation of boundary-layer based thunderstorm development is forecast to
generally remain to the north of the international border.

While the risk for severe thunderstorms appears largely conditional,
guidance does indicate that a weak surface low may develop within
the pre-frontal troughing and provide a potential focus for
convective development across northwestern North Dakota late this
afternoon and evening. If this forcing, coupled with the approach
of convective temperatures, is sufficient to overcome the mid-level
inhibition, forecast soundings indicate the environment will be
conducive to supercell development.

..Kerr/Lyons.. 08/20/2025

$$

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ACUS01 KWNS 201231
SWODY1
SPC AC 201230

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Wed Aug 20 2025

Valid 201300Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
TEXAS/DEEP SOUTH AND NORTHERN PLAINS...

...SUMMARY...
Scattered thunderstorms from Texas across the Lower Mississippi
Valley and Gulf Coast states may pose a risk for localized damaging
wind gusts this afternoon and evening. Isolated severe thunderstorms
may also occur across eastern Montana and northern North Dakota.

...Texas to Lower Mississippi Valley/Gulf Coast States...
A convectively augmented effective front will continue to progress
southward, southward-shifting the potential for microburst-related
wind damage regionally. Diurnal heating of a moist boundary layer
will result in a moderately to strongly unstable and weakly capped
airmass by afternoon, with the strongest buoyancy (2500+ J/kg
MLCAPE) expected across central/east Texas east-northeastward to Mississippi/western Alabama/southern Tennessee. Some small-scale
clusters may evolve, but weak vertical shear will otherwise tend to
keep the overall pulse-type damaging wind potential very isolated.

...Northern Plains...
The region will be influenced by late-day/nighttime height falls as
a shortwave trough emerges eastward from the Canadian Rockies, with
an eastward-advancing cold front moving across eastern Montana into
North Dakota tonight. A narrow corridor of moderate to large
buoyancy is expected along/ahead of the surface cold front, and near
a pre-frontal surface trough. Beneath a plume of warm elevated
mixed-layer air, mid/upper-level support for the initiation of
boundary-layer based thunderstorm development is forecast to
generally remain north of the international border.

One exception may be in the post-frontal environment across eastern
Montana, the environment would be conducive to a few severe storms
capable of hail/wind. While the risk for severe thunderstorms
appears largely conditional into North Dakota where stronger
destabilization is expected, isolated deeper convective development
is plausible across northwestern North Dakota in proximity to the
surface low/front late this afternoon, and more so this evening.
Should this occur, forecast soundings indicate the environment would
support isolated supercell development and related severe-weather
risks.

..Guyer/Marsh.. 08/20/2025

$$

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ACUS01 KWNS 201630
SWODY1
SPC AC 201628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Wed Aug 20 2025

Valid 201630Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
TEXAS INTO THE LOWER MISSISSIPPI VALLEY/SOUTHEAST...AND THE NORTHERN
PLAINS...

...SUMMARY...
Scattered thunderstorms from Texas across the Lower Mississippi
Valley and Southeast may pose a risk for localized damaging wind
gusts this afternoon and evening. Isolated severe thunderstorms may
also occur across parts of central/eastern Montana and northern
North Dakota, mainly this evening and overnight.

...Texas into the Lower Mississippi Valley and Southeast...
A convectively reinforced front/outflow boundary from
earlier/ongoing convection should once again provide a focus for
renewed convective development this afternoon from parts of
west-central TX eastward into the lower MS Valley and Southeast.
Mid-level flow and related deep-layer shear are expected to remain
weak, which should generally limit thunderstorm organization. Still,
a moderately to strongly unstable environment will exist along/south
of the front with continued daytime heating, with scattered to
numerous thunderstorms likely. Similar to yesterday, wet microbursts
from convective downdrafts may produce isolated damaging winds as
low-level lapse rates become steepened. These thunderstorms should
weaken through the evening with the loss of daytime heating.

...Northern Plains...
The northern Plains will be influenced by late-day/overnight
mid-level height falls as a shortwave trough moves eastward from the Canadian/northern Rockies, with a related cold front moving across central/eastern MT into ND tonight. A narrow corridor of moderate to
strong instability will likely develop along/ahead of the cold
front, and near a pre-frontal surface trough. But, warm mid-level
temperatures and a capped airmass will likely exist along/south of
the international border, which should inhibit robust convective
development for much of the day.

One exception may be in the post-frontal environment across eastern
MT this evening/tonight. The environment here should be conducive to
isolated severe thunderstorms capable of producing both large hail
and severe gusts. While the risk for severe thunderstorms appears
more conditional into ND where stronger destabilization is expected,
isolated convective development may still occur across northwestern
ND in proximity to the surface low/front late this afternoon, and
perhaps more so this evening/overnight. Should this occur, forecast
soundings indicate the environment would support isolated supercell
development with a related hail/wind threat.

..Gleason/Wendt.. 08/20/2025

$$

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ACUS01 KWNS 202000
SWODY1
SPC AC 201958

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Wed Aug 20 2025

Valid 202000Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
TEXAS INTO THE LOWER MISSISSIPPI VALLEY/SOUTHEAST...AND THE NORTHERN
PLAINS...

...SUMMARY...
Scattered thunderstorms from Texas across the Lower Mississippi
Valley and Southeast may pose a risk for localized damaging wind
gusts this afternoon and evening. Isolated severe thunderstorms may
also occur across parts of central/eastern Montana and northern
North Dakota, mainly this evening and overnight.

...20z Update...
Changes were made to clear the Marginal Risk across portions of
central Texas where thunderstorms and outflow have moved southward.

The Marginal Risk was expanded across the Southeast into portions of
northwest Georgia and eastern Alabama. A cluster of thunderstorms
continues to sag southward into this region, with cores exhibiting
some uptick in intensity. See MCD#1995.

Otherwise, the outlook remains on track with no additional changes
needed. See previous discussion below for more information.

..Thornton.. 08/20/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Aug 20 2025/

...Texas into the Lower Mississippi Valley and Southeast...
A convectively reinforced front/outflow boundary from
earlier/ongoing convection should once again provide a focus for
renewed convective development this afternoon from parts of
west-central TX eastward into the lower MS Valley and Southeast.
Mid-level flow and related deep-layer shear are expected to remain
weak, which should generally limit thunderstorm organization. Still,
a moderately to strongly unstable environment will exist along/south
of the front with continued daytime heating, with scattered to
numerous thunderstorms likely. Similar to yesterday, wet microbursts
from convective downdrafts may produce isolated damaging winds as
low-level lapse rates become steepened. These thunderstorms should
weaken through the evening with the loss of daytime heating.

...Northern Plains...
The northern Plains will be influenced by late-day/overnight
mid-level height falls as a shortwave trough moves eastward from the Canadian/northern Rockies, with a related cold front moving across central/eastern MT into ND tonight. A narrow corridor of moderate to
strong instability will likely develop along/ahead of the cold
front, and near a pre-frontal surface trough. But, warm mid-level
temperatures and a capped airmass will likely exist along/south of
the international border, which should inhibit robust convective
development for much of the day.

One exception may be in the post-frontal environment across eastern
MT this evening/tonight. The environment here should be conducive to
isolated severe thunderstorms capable of producing both large hail
and severe gusts. While the risk for severe thunderstorms appears
more conditional into ND where stronger destabilization is expected,
isolated convective development may still occur across northwestern
ND in proximity to the surface low/front late this afternoon, and
perhaps more so this evening/overnight. Should this occur, forecast
soundings indicate the environment would support isolated supercell
development with a related hail/wind threat.

$$

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ACUS01 KWNS 210041
SWODY1
SPC AC 210039

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0739 PM CDT Wed Aug 20 2025

Valid 210100Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF CENTRAL MONTANA INTO NORTHERN NORTH DAKOTA AND ACROSS PORTIONS OF
THE LOWER MISSISSIPPI VALLEY...

...SUMMARY...
Isolated severe thunderstorms are possible from central Montana into
northern North Dakota tonight. A few wind gusts may also be noted
with storms over the lower Mississippi Valley early this evening.

...01z Update...

Early-evening water-vapor imagery depicts an upper trough extending
across southeast BC into the northern Rockies. This feature is
forecast to advance to near the AB/SK border by the end of the
period, with modest mid-level height falls expected across northeast
MT into ND. As 500mb speed max strengthens over southern SK later
tonight some increase in LLJ should be noted across western ND -
just ahead of the progressive surface front. Isolated robust
convection has developed ahead of the short wave from southwest SK
into central MT. This activity may continue to generate gusty winds
and hail, but new updrafts are expected downstream across western ND
with time. Vis imagery suggests high-based updrafts are deepening
across southeast MT into southwest ND, and isolated severe may
ultimately evolve along the northern edge of this steep lapse rate
plume, immediately ahead of the front.

Boundary-layer heating was instrumental in scattered-widespread
convection across the northern Gulf States this afternoon. While
considerable convective overturning has occurred, a pocket of modest instability persists across much of LA. Cluster of strong-locally
severe thunderstorms will drift south across this region over the
next several hours. Boundary-layer cooling will negate updraft
intensity by mid evening.

..Darrow.. 08/21/2025

$$

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ACUS01 KWNS 210542
SWODY1
SPC AC 210540

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1240 AM CDT Thu Aug 21 2025

Valid 211200Z - 221200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS INTO MINNESOTA...

...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
northern Plains into Minnesota later this afternoon and evening.
Severe gusts and hail are the primary concern.

...Northern Plains/Minnesota...

Northern Plains upper ridge will flatten considerably during the
day1 period as heights fall ahead of a digging upper trough. Early
this morning, water-vapor imagery depicts the short wave along the
BC/AB border. This feature is forecast to advance into eastern SK by
22/00z before it advances to the SK/MB border by the end of the
period. While the primary large-scale forcing will be noted north of
the international border, high-level diffluent flow will be noted
across the eastern Dakotas/Minnesota - coincident with the front
that will be draped across this region at peak heating. Latest model
guidance suggests a plume of steep low-level lapse rates will extend
across the central Plains into south central SD where surface
temperatures are expected to soar through the mid 90s. The majority
of CAM guidance struggles to develop more than isolated convection
along the surface front - possibly due to the aforementioned weak
large-scale ascent. In addition, LLJ does not strengthen appreciably
ahead of the boundary, and this also supports isolated coverage.
Notably, during the overnight hours, robust convection may develop
within a weak warm advection zone across eastern SD into southwest
MN - possibly in response to a bit more forcing along the southern
fringe of the digging upper trough after 06z. Wind/hail will be the
primary threats with both the late-afternoon and overnight
convection. Isolated storm coverage favors MRGL Risk at this time.

Upstream, surface front will trail across the southern Black Hills
into central WY by peak heating. Northeast upslope flow should
encourage convection to develop across the higher terrain by late
afternoon. While forecast buoyancy is not expected to be
particularly strong, adequate deep-layer shear will prove supportive
of organized updrafts that could generate hail/wind.

..Darrow/Lyons.. 08/21/2025

$$

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ACUS01 KWNS 211253
SWODY1
SPC AC 211251

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0751 AM CDT Thu Aug 21 2025

Valid 211300Z - 221200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS/UPPER MIDWEST AND SOUTHERN ARIZONA...

...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
northern Plains and Upper Midwest this afternoon and evening, with
severe wind gusts and hail the primary concerns. A few strong to
severe storms could also occur across southern Arizona.

...Northern Plains/Minnesota...
Late-day height falls are expected regionally in relation to an
amplifying shortwave trough over the Canadian prairies. While the
primary large-scale forcing will be north of the international
border, high-level diffluent flow is expected across the eastern Dakotas/Minnesota, coincident with the front that will be draped
across the region at peak heating. Short-term models (HRRR/RRFS) are
tending to limit late-afternoon/evening convective development,
while most global models and most HREF constituents are a bit more
aggressive, which is plausible and lends credence to the potential
for at isolated severe storms within a moderately to strongly
unstable environment near the front. Deep-layer should be sufficient
to potentially yield a few supercells. Increasing storm coverage
later into the evening/overnight will be supported by an increasing
low-level jet.

...North-central High Plains including eastern Wyoming...
Northeasterly low-level upslope flow evolving within the
post-frontal environment, and differential heating in vicinity of
higher terrain, are expected to influence widely scattered
thunderstorm development by late afternoon, particularly across
eastern Wyoming. While forecast buoyancy is not expected to be
particularly strong, adequate deep-layer shear will prove supportive
of organized updrafts that could generate hail/wind, including the
possibility that a couple of eastward-moving clusters could evolve
by early evening.

...Southern Arizona...
The upper ridge should shift slightly northward regionally, with a
modest enhancement to mid-level easterly flow late today
particularly across southeast Arizona. With isolated storm
development expected initially over the rim/mountains this
afternoon, storms should drift west-southwestward into a moist/very
hot boundary layer, with the potential for outflows/blowing dust to
reach the desert floor.

..Guyer/Marsh.. 08/21/2025

$$

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ACUS01 KWNS 211632
SWODY1
SPC AC 211630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Thu Aug 21 2025

Valid 211630Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN SOUTH DAKOTA INTO NORTHWEST MINNESOTA...

...SUMMARY...
Scattered severe thunderstorms are possible across portions of the
northern Plains and Upper Midwest this afternoon into tonight, with
severe wind gusts and large hail the primary concerns. A few strong
to severe storms may also occur across parts of southern Arizona.

...Northern Plains into the Upper Midwest...
Enhanced mid/upper-level westerly flow will persist today across the
northern Plains/Upper Midwest, sandwiched between upper troughing
over the Canadian Prairie provinces and a stout mid/upper-level
anticyclone centered over the Four Corners/Southwest. Multiple
low-amplitude perturbations, some associated with ongoing convection
across eastern MT into ND and northern MN, will move eastward today
and potentially aid in additional thunderstorm development this
afternoon and evening. At the surface, the primary low associated
with the upper trough will remain well north in Canada, with a
trailing cold front expected to continue moving east-southeastward
across the northern Plains and Upper Midwest through the period.

There is still considerable uncertainty regarding potential robust
convective development and subsequent evolution along/near the cold
front later today. This is mainly due to the stronger large-scale
ascent aloft forecast to remain in central Canada, and capping
concerns with southward extent along the front in the northern
Plains due to fairly warm low/mid-level temperatures. Multiple
potential scenarios remain plausible, ranging from little to no
convection developing this afternoon/evening, as some recent convection-allowing model guidance suggests, to multiple
supercells/clusters forming in a narrow zone of favorable
instability and shear.

Given these considerations, confidence is lower than usual regarding
severe potential across the northern Plains/Upper Midwest. Still, a
narrow corridor of moderate to strong instability will likely exist
late this afternoon and into the evening along/near the front from
northwest MN into eastern SD, aided by steep mid-level lapse rates
and diurnal heating. Modest low-level flow veering to westerly at
mid/upper levels will foster sufficient deep-layer shear (around
30-40 kt) to support organized convection, including the potential
for a few supercells and clusters. Scattered large hail and
severe/damaging winds may occur with this activity if it develops
and can be sustained. So, a Slight Risk has been included with this
update to account for this potential.

Farther west, a post-frontal regime will exist this
afternoon/evening across the northern High Plains of northeast WY
and vicinity. Low-level upslope flow against the higher terrain may
promote a supercell or two to develop and spread east-southeastward
through the late afternoon and evening, with mainly an isolated hail
threat. Some potential for clustering is also apparent this
evening/overnight across parts of SD along/near the surface front.
If this occurs, then a continued threat for strong to locally severe
gusts may persist. Have therefore connected the Marginal Risks
across SD for this possibility.

...Arizona...
Modest mid/upper-level easterly flow will persist today over
southern AZ, to the south of an anticyclone aloft centered over the
Four Corners. Convection that initially develops over the higher
terrain of southeast/east-central AZ may gradually develop westward
into lower elevations through the late afternoon and continuing into
the evening. Ample daytime heating of a seasonably moist low-level
airmass already in place (reference observed 12Z PHX sounding) will
act to further steepen low/mid-level lapse rates. At least isolated
strong to severe gusts may occur with these thunderstorms given the
favorable thermodynamic/lapse rate environment. The Marginal Risk
has been expanded some to account for latest short-term guidance
trends.

..Gleason/Supinie.. 08/21/2025

$$

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ACUS01 KWNS 211954
SWODY1
SPC AC 211953

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0253 PM CDT Thu Aug 21 2025

Valid 212000Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN SOUTH DAKOTA INTO NORTHWEST MINNESOTA...

...SUMMARY...
Scattered severe thunderstorms are possible across portions of the
northern Plains and Upper Midwest this afternoon into tonight, with
severe wind gusts and large hail the primary concerns. A few strong
to severe storms may also occur across parts of southern Arizona.

...20z Update...
No changes are needed to the D1 Convective Outlook. See previous
discussion for more information.

..Thornton.. 08/21/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Aug 21 2025/

...Northern Plains into the Upper Midwest...
Enhanced mid/upper-level westerly flow will persist today across the
northern Plains/Upper Midwest, sandwiched between upper troughing
over the Canadian Prairie provinces and a stout mid/upper-level
anticyclone centered over the Four Corners/Southwest. Multiple
low-amplitude perturbations, some associated with ongoing convection
across eastern MT into ND and northern MN, will move eastward today
and potentially aid in additional thunderstorm development this
afternoon and evening. At the surface, the primary low associated
with the upper trough will remain well north in Canada, with a
trailing cold front expected to continue moving east-southeastward
across the northern Plains and Upper Midwest through the period.

There is still considerable uncertainty regarding potential robust
convective development and subsequent evolution along/near the cold
front later today. This is mainly due to the stronger large-scale
ascent aloft forecast to remain in central Canada, and capping
concerns with southward extent along the front in the northern
Plains due to fairly warm low/mid-level temperatures. Multiple
potential scenarios remain plausible, ranging from little to no
convection developing this afternoon/evening, as some recent convection-allowing model guidance suggests, to multiple
supercells/clusters forming in a narrow zone of favorable
instability and shear.

Given these considerations, confidence is lower than usual regarding
severe potential across the northern Plains/Upper Midwest. Still, a
narrow corridor of moderate to strong instability will likely exist
late this afternoon and into the evening along/near the front from
northwest MN into eastern SD, aided by steep mid-level lapse rates
and diurnal heating. Modest low-level flow veering to westerly at
mid/upper levels will foster sufficient deep-layer shear (around
30-40 kt) to support organized convection, including the potential
for a few supercells and clusters. Scattered large hail and
severe/damaging winds may occur with this activity if it develops
and can be sustained. So, a Slight Risk has been included with this
update to account for this potential.

Farther west, a post-frontal regime will exist this
afternoon/evening across the northern High Plains of northeast WY
and vicinity. Low-level upslope flow against the higher terrain may
promote a supercell or two to develop and spread east-southeastward
through the late afternoon and evening, with mainly an isolated hail
threat. Some potential for clustering is also apparent this
evening/overnight across parts of SD along/near the surface front.
If this occurs, then a continued threat for strong to locally severe
gusts may persist. Have therefore connected the Marginal Risks
across SD for this possibility.

...Arizona...
Modest mid/upper-level easterly flow will persist today over
southern AZ, to the south of an anticyclone aloft centered over the
Four Corners. Convection that initially develops over the higher
terrain of southeast/east-central AZ may gradually develop westward
into lower elevations through the late afternoon and continuing into
the evening. Ample daytime heating of a seasonably moist low-level
airmass already in place (reference observed 12Z PHX sounding) will
act to further steepen low/mid-level lapse rates. At least isolated
strong to severe gusts may occur with these thunderstorms given the
favorable thermodynamic/lapse rate environment. The Marginal Risk
has been expanded some to account for latest short-term guidance
trends.

$$

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ACUS01 KWNS 220056
SWODY1
SPC AC 220055

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0755 PM CDT Thu Aug 21 2025

Valid 220100Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE NORTHERN PLAINS...

...SUMMARY...
Scattered severe thunderstorms remain possible across portions of
the northern Plains and Upper Midwest tonight, with severe wind
gusts and large hail the primary concerns. A few strong to severe
storms may also occur across parts of southern Arizona this evening.

...01z Update...

Upper ridge has flattened considerably across the northern Plains in
response to SK short-wave trough. Mid-level flow will gradually veer
across the Dakotas as a strong 500mb speed max translates through
the base of the trough along the international border late tonight.
As this occurs, surface front currently draped from northwest
MN-central SD will gradually sag southeast. Thunderstorm coverage
along the boundary remains isolated, and this may continue much of
the evening until a secondary short wave approaches later tonight.
While a meaningful LLJ is not expected ahead of this feature, latest
model guidance continues to suggest a weak disturbance will eject
across northeast WY/Black Hills region. Elevated convection could
markedly increase after 06z across much of SD along/north of the
front. Earlier thoughts regarding severe continue, but have lowered
severe probabilities across northern MN to reflect less storm
coverage along this portion of the boundary.

AZ: Upper ridge is holding across the Four Corners region and
favorable easterly flow is guiding terrain-induced convection toward
the lower deserts. Scattered robust convection is expected to spread
toward the more populated ares of the PHX metro over the next few
hours. Gusty winds are the primary concern.

..Darrow.. 08/22/2025

$$

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ACUS01 KWNS 220541
SWODY1
SPC AC 220539

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1239 AM CDT Fri Aug 22 2025

Valid 221200Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL/NORTHERN HIGH PLAINS AND UPPER MIDWEST AND OVER PARTS OF THE SOUTHWESTERN UNITED STATES...

...SUMMARY...
Strong to locally severe thunderstorms are possible from parts of
the central and northern High Plains into the Upper Midwest, and
across parts of the southwestern United States.

...Central/Northern High Plains-Upper Midwest...

Central Canadian upper trough is forecast to advance into western
ON/MN by 23/00z as 500mb speed max settles into the base of the
trough over the upper Red River region of eastern ND/MN. High-level
diffluent flow will be noted across much of the Upper Midwest ahead
of this feature which will encourage deep convection along the
frontal zone from the upper Great Lakes into portions of the Mid MO
Valley. Early in the period, remnant MCS activity may be ongoing
across southern MN/southeast SD. However, left-over convective
debris may also inhibit surface heating, but may enhance an
afternoon boundary for potential thunderstorm development. Latest
model guidance suggests the front may be multi faceted with some of
the stronger boundary-layer heating expected behind the initial wind
shift across SD into northern MN - well northwest of high PW air
mass. As a result, forecast soundings suggest surface parcels may
struggle to reach convective temperature along the leading wind
shift, with only modest lapse rates expected. Even so, deep-layer
shear will be more than adequate for sustaining organized updrafts
where frontal convergence aids convective development.

Higher confidence in robust convection is expected across portions
of CO into southeast WY. Strong surface heating should aid
thunderstorm development across the higher terrain, along the
northern periphery of the Four Corners upper high. This activity
should propagate southeast toward lower elevations where it will
encounter favorably moist, but weak upslope flow. Hail and wind are
possible with this activity.

...Arizona...

Upper high is forecast to shift slowly west across southern UT
during the day1 period. This will ensure modest easterly 500mb flow
across the southern half of AZ. Strong boundary-layer heating will
once again prove instrumental in convective development over the
higher terrain. This activity will spread toward the lower deserts
during the evening with an attendant risk for at least locally
severe wind gusts.

..Darrow/Weinman.. 08/22/2025

$$

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ACUS01 KWNS 221251
SWODY1
SPC AC 221250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Fri Aug 22 2025

Valid 221300Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL HIGH PLAINS TO THE UPPER MIDWEST AS WELL AS ARIZONA...

...SUMMARY...
Strong to locally severe thunderstorms are possible from parts of
the central and northern High Plains to the Upper Midwest, and
across parts of Arizona.

...Upper Midwest/Upper Great Lakes...
Upper trough amplification will continue to occur over
Manitoba/northern Ontario through tonight, with consequential height
falls over the upper Great Lakes. A cold front will continue to
advance southeastward regionally, with a semi-moist air mass
preceding it. A consequential factor for portions of the region will
be an MCS centered across far eastern South Dakota early this
morning, which will continue to disturb the frontal zone and nearby
warm sector for the first part of the day. This may especially be
the case across southern Minnesota and vicinity.

But on the periphery of the MCS-influenced corridor, potential
severe storm development could occur by late afternoon, perhaps most
likely across eastern Nebraska and western Iowa, but also across
northwest Wisconsin/Upper Michigan where vertical shear will be
stronger but with more modest buoyancy. Hail and damaging winds
would be possible in both scenarios, but likely on a relatively
isolated basis.

...Wyoming/Colorado and central High Plains...
A subtle ridge-peripheral disturbance noted in water vapor imagery,
along with strong surface heating, should aid thunderstorm
development initially across Wyoming/Colorado. This activity should
propagate east-southeast toward lower elevations in the presence of
moist low-level upslope flow. Hail and wind are possible with this
activity, especially within a corridor across interior/southeast
Wyoming into northeast/east-central Colorado.

...Arizona...
The upper high will shift west-northwestward through tonight,
maintaining and potentially strengthening easterly mid-level winds
across southern Arizona, in addition to the possibility of slightly
cooler (degree or two C) mid-level temperatures. Lingering morning
cloud cover should gradually abate into the afternoon, with a very hot/residually moist boundary layer contributing to widely scattered thunderstorm development, initially over higher terrain.
West/southwestward spreading storms will pose the potential for
strong wind gusts/blowing dust onto the desert floor.

..Guyer/Kerr.. 08/22/2025

$$

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ACUS01 KWNS 221632
SWODY1
SPC AC 221630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Fri Aug 22 2025

Valid 221630Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE NORTHERN/CENTRAL HIGH PLAINS TO THE UPPER MIDWEST/GREAT
LAKES...AND PORTIONS OF SOUTHERN/CENTRAL ARIZONA...

...SUMMARY...
Strong to locally severe thunderstorms may occur today from parts of
the northern and central High Plains to the Upper Midwest/Great
Lakes, and separately across parts of Arizona. Damaging winds and
occasional hail should be the main threats.

...Synopsis...
A mid/upper-level trough/low centered over Manitoba late this
morning will move east-southeastward across Ontario and the Upper
Midwest/Great Lakes through the period. At the surface, a weak cold
front is forecast to develop southeastward across the
northern/central High Plains and Upper Midwest this afternoon and
evening. This boundary should serve as a focus for additional
thunderstorm development later today, some of which could become
strong to severe. A mid/upper-level anticyclone will remain anchored
over the Four Corners region today, with modest easterly mid-level
flow persisting over parts of AZ.

...Northern/Central High Plains to the Upper Midwest/Great Lakes...
A broad zone of isolated strong to severe thunderstorm potential
remains evident today, generally along/near a convectively
reinforced cold front extending from the central High Plains
east-northeastward to the Upper Midwest/Great Lakes. Within this
broad zone, three somewhat separate regimes of severe potential are
apparent.

Thunderstorms have recently developed across parts of
central/eastern MN and far northwest WI ahead of a remnant
MCV/subtle mid-level shortwave trough. The airmass downstream from
this activity across northern WI into the U.P. of MI is only weakly
unstable, with scattered to broken mid/upper-level clouds present.
Stronger mid-level flow is also forecast to generally lag behind the
surface cold front across this region. Still, a small cluster or two
may eventually evolve from the ongoing convection in MN, and spread
eastward through the afternoon/early evening. Occasional damaging
winds should be the main threat, but some hail may also occur with
the stronger cores given cool mid-level temperatures and around
25-35 kt of deep-layer shear aiding updraft organization. Considered
adding a Slight Risk for severe/damaging winds across parts of
northern WI and vicinity, but confidence in more robust
destabilization occurring remains low. Trends will be monitored for
a possible upgrade at 20Z, if needed.

Outflow from earlier thunderstorms continues to advance southward
across parts of eastern NE and northwest IA per recent surface
observations and visible satellite imagery. The effect of this
outflow surge on additional thunderstorm development this afternoon
remains unclear, as the primary cold front lags the outflow by a
considerable extent. Some guidance suggests that a couple of
supercells or perhaps a small cluster may develop over far southeast
SD into eastern NE and western IA later today as the airmass across
these areas gradually destabilizes. At least an isolated risk for
severe hail and damaging winds will exist if this occurs. But, the
overall severe threat remains too uncertain for a categorical
upgrade with this outlook update.

Farther west, a subtle mid-level ridge-peripheral disturbance noted
in water vapor imagery across southern WY and northwest CO, along
with strong daytime heating, should aid thunderstorm development
initially across the higher terrain of the central Rockies later
this afternoon. This activity should propagate east-southeastward
toward lower elevations in the presence of moist, post-frontal
low-level upslope flow. Isolated severe hail and winds are possible
with this activity, especially within a corridor across
interior/southeast WY into northeast/east-central CO.

...Arizona...
A fair amount of convective cloud debris is present today across
parts of AZ per recent visible satellite imagery. This may tend to
delay diurnal heating and related steepening of low-level lapse
rates to some extent. But, eventual airmass recovery is still
expected by late afternoon/early evening, with seasonably moist
low-levels still noted on the 12Z observed PHX sounding.
Thunderstorms should once again form initially along the higher
terrain of the Mogollon Rim and southeastern AZ before spreading west-southwestward across the lower elevations of central/southern
AZ through the evening. Sufficient instability, a very well-mixed
boundary layer, and modest easterly mid-level flow should all
support an isolated threat for severe/damaging winds with this
activity.

..Gleason/Moore.. 08/22/2025

$$

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ACUS01 KWNS 222003
SWODY1
SPC AC 222001

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0301 PM CDT Fri Aug 22 2025

Valid 222000Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN/CENTRAL HIGH PLAINS TO THE UPPER MIDWEST/GREAT
LAKES...AND PORTIONS OF SOUTHERN/CENTRAL ARIZONA...

...SUMMARY...
Strong to locally severe thunderstorms may occur today from parts of
the northern and central High Plains to the Upper Midwest/Great
Lakes, and separately across parts of Arizona. Damaging winds and
occasional hail should be the main threats.

...20z Update...
Minor adjustments were made to remove thunder chances and the
Marginal Risk behind ongoing convection from Iowa to Wisconsin.
Otherwise, the forecast remains on track. See previous discussion
below for more information.

..Thornton.. 08/22/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Aug 22 2025/

...Synopsis...
A mid/upper-level trough/low centered over Manitoba late this
morning will move east-southeastward across Ontario and the Upper
Midwest/Great Lakes through the period. At the surface, a weak cold
front is forecast to develop southeastward across the
northern/central High Plains and Upper Midwest this afternoon and
evening. This boundary should serve as a focus for additional
thunderstorm development later today, some of which could become
strong to severe. A mid/upper-level anticyclone will remain anchored
over the Four Corners region today, with modest easterly mid-level
flow persisting over parts of AZ.

...Northern/Central High Plains to the Upper Midwest/Great Lakes...
A broad zone of isolated strong to severe thunderstorm potential
remains evident today, generally along/near a convectively
reinforced cold front extending from the central High Plains
east-northeastward to the Upper Midwest/Great Lakes. Within this
broad zone, three somewhat separate regimes of severe potential are
apparent.

Thunderstorms have recently developed across parts of
central/eastern MN and far northwest WI ahead of a remnant
MCV/subtle mid-level shortwave trough. The airmass downstream from
this activity across northern WI into the U.P. of MI is only weakly
unstable, with scattered to broken mid/upper-level clouds present.
Stronger mid-level flow is also forecast to generally lag behind the
surface cold front across this region. Still, a small cluster or two
may eventually evolve from the ongoing convection in MN, and spread
eastward through the afternoon/early evening. Occasional damaging
winds should be the main threat, but some hail may also occur with
the stronger cores given cool mid-level temperatures and around
25-35 kt of deep-layer shear aiding updraft organization. Considered
adding a Slight Risk for severe/damaging winds across parts of
northern WI and vicinity, but confidence in more robust
destabilization occurring remains low. Trends will be monitored for
a possible upgrade at 20Z, if needed.

Outflow from earlier thunderstorms continues to advance southward
across parts of eastern NE and northwest IA per recent surface
observations and visible satellite imagery. The effect of this
outflow surge on additional thunderstorm development this afternoon
remains unclear, as the primary cold front lags the outflow by a
considerable extent. Some guidance suggests that a couple of
supercells or perhaps a small cluster may develop over far southeast
SD into eastern NE and western IA later today as the airmass across
these areas gradually destabilizes. At least an isolated risk for
severe hail and damaging winds will exist if this occurs. But, the
overall severe threat remains too uncertain for a categorical
upgrade with this outlook update.

Farther west, a subtle mid-level ridge-peripheral disturbance noted
in water vapor imagery across southern WY and northwest CO, along
with strong daytime heating, should aid thunderstorm development
initially across the higher terrain of the central Rockies later
this afternoon. This activity should propagate east-southeastward
toward lower elevations in the presence of moist, post-frontal
low-level upslope flow. Isolated severe hail and winds are possible
with this activity, especially within a corridor across
interior/southeast WY into northeast/east-central CO.

...Arizona...
A fair amount of convective cloud debris is present today across
parts of AZ per recent visible satellite imagery. This may tend to
delay diurnal heating and related steepening of low-level lapse
rates to some extent. But, eventual airmass recovery is still
expected by late afternoon/early evening, with seasonably moist
low-levels still noted on the 12Z observed PHX sounding.
Thunderstorms should once again form initially along the higher
terrain of the Mogollon Rim and southeastern AZ before spreading west-southwestward across the lower elevations of central/southern
AZ through the evening. Sufficient instability, a very well-mixed
boundary layer, and modest easterly mid-level flow should all
support an isolated threat for severe/damaging winds with this
activity.

$$

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ACUS01 KWNS 230059
SWODY1
SPC AC 230057

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0757 PM CDT Fri Aug 22 2025

Valid 230100Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
HIGH PLAINS TO THE UPPER MIDWEST...

...SUMMARY...
Isolated strong to locally severe thunderstorms may occur this
evening and into tonight from parts of the northern and central High
Plains to the Upper Midwest/Great Lakes, and separately across parts
of Arizona. Damaging winds and occasional hail should be the main
threats.

...Upper Midwest...
A cluster of storms across northern Wisconsin and the UP has now
moved into Canada and is weakening on the eastern periphery of the
better instability. In the wake of this activity, a few storms have
developed along a cold front moving through northern Minnesota with
a few isolated showers/storms developing ahead of it. Have adjusted
the thunder line west to account for these storms and will keep the
marginal across southeast Minnesota and northwest Wisconsin where
instability remains. This threat will likely only continue for a few
more hours before a cooling boundary layer stabilizes the area.

...Central Plains into the central High Plains...
The earlier cluster of storms across eastern Nebraska moved south
and weakened as it moved into a more stable airmass across southern
Nebraska. However, an additional storm developed across east-central
Nebraska where 2000 J/kg MLCAPE is present. This threat may remain
for a few more hours before eventual nocturnal stabilization ends
the threat.

Storms across Wyoming and northeast Colorado have been relatively
weak thus far. However, as heights continue to fall across the
region, expect these storms to maintain with additional storm
development also possible. Weak to moderate instability with 30 to
35 knots of shear will support the potential for isolated strong
storms capable of large hail or severe wind gusts this evening and
into the early overnight hours.

..Bentley.. 08/23/2025

$$

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ACUS01 KWNS 230546
SWODY1
SPC AC 230544

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1244 AM CDT Sat Aug 23 2025

Valid 231200Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL HIGH PLAINS....

...SUMMARY...
Strong to isolated severe storms are possible in the central High
Plains today.

...Synopsis...
A mid-level trough will amplify across the Great Lakes today with
strengthening mid-level flow across the Northern Plains. Surface
high pressure building into the northern Plains this morning will
advance into the central Plains by this afternoon and push a cold
front south across the Plains and Upper Midwest. Farther east, a
cold front, associated with the mid-level trough across the northern
Great Lakes, will move across the Great Lakes and Ohio Valley.

...Central High Plains...
Upslope flow in the wake of the cold front across the central High
Plains may provide an environment favorable for a few isolated
strong to severe storms this afternoon/evening. Terrain driven
storms are anticipated across much of the central Rockies. A few
storms are expected to move off of the higher terrain, and with
support from low-level upslope flow, maintain themselves along the
Front Range as they move south. Steep mid-level lapse rates and
around 35 to 40 knots of mid-level flow will support the potential
for isolated supercell structures capable of isolated large hail and
severe wind gusts. Storm motions around 350 degrees and storm
formation expected along the mountains and immediate foothills will
result in a very narrow area of risk along the Front Range from
southeast Wyoming to central Colorado. Slightly stronger instability
across southeast Colorado and the potential for some clustering of
storms supports a slightly wider marginal extending into this
region.

...Great Lakes...
A few showers and thunderstorms will likely develop along a cold
front as it moves across the Great Lakes this afternoon. Warm 700mb temperatures in the presence of only low 60s dewpoints will limit
overall buoyancy and updraft strength. Therefore, no severe
thunderstorms are expected.

..Bentley/Weinman.. 08/23/2025

$$

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ACUS01 KWNS 231247
SWODY1
SPC AC 231246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Sat Aug 23 2025

Valid 231300Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE FRONT RANGE/CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated severe storms are possible near the Colorado/Wyoming Front
Range and central High Plains this afternoon and evening.

...Front Range/Central High Plains...
Multiple subtle upper ridge-peripheral impulses and a belt of
moderately strong northwesterly winds aloft will influence the
region as low-level upslope flow increases late today within the
post-frontal environment. At least widely scattered thunderstorm
development is expected initially over the mountains, with
subsequent intensification as storms develop east-southeastward into
a moderately unstable air mass, with buoyancy maximized
near/immediately east of the urban corridor/I-25. Steep mid-level
lapse rates and 40+ kt effective shear will support the possibility
of isolated supercells capable of large hail and some locally
stronger wind gusts through early evening.

...Midwest/Great Lakes...
A few showers and thunderstorms will likely develop along a cold
front as it moves across the Great Lakes/Midwest this afternoon.
Warm 700mb temperatures in the presence of only low 60s dewpoints
will limit overall buoyancy and updraft strength, likely keeping
severe-storm potential minimal.

..Guyer/Kerr.. 08/23/2025

$$

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ACUS01 KWNS 231624
SWODY1
SPC AC 231622

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1122 AM CDT Sat Aug 23 2025

Valid 231630Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE COLORADO/WYOMING FRONT RANGE AND ADJACENT CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated severe thunderstorms appear possible near the
Colorado/Wyoming Front Range and central High Plains this afternoon
and evening.

...Front Range/Central High Plains...
A mid/upper-level anticyclone centered over the Southwest and Four
Corners regions will move little today, with ridging extending
northward across much of the Great Basin and Northwest. Modestly
enhanced northwesterly mid-level flow will exist today across the
central Rockies and adjacent High Plains. A moist post-frontal
airmass will remain in place across these areas, with surface
dewpoints generally in the mid to upper 50s. Low cloud cover remains
prevalent across the central High Plains late this morning, which
should continue to hinder destabilization to some extent. Even so,
gradual thunderstorm development should eventually occur over the
higher terrain by late afternoon as persistent low-level upslope
flow aids parcels in reaching their LFCs. This activity should
spread generally south-southeastward through the evening along/near
the I-25 corridor, while posing an isolated threat for mainly hail
due to a combination of modestly steepened lapse rates aloft,
sufficient deep-layer shear, and weak to moderate MLCAPE. Occasional strong/gusty winds may also occur.

...Great Lakes/Midwest...
Isolated thunderstorms should develop along a cold front this
afternoon as it advances eastward across part of the Great
Lakes/Midwest. Warm low/mid-level temperatures in the presence of
generally low/mid 60s surface dewpoints should limit buoyancy and
updraft strength, likely keeping the overall severe potential low.

..Gleason/Moore.. 08/23/2025

$$

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ACUS01 KWNS 231930
SWODY1
SPC AC 231928

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0228 PM CDT Sat Aug 23 2025

Valid 232000Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE COLORADO/WYOMING FRONT RANGE AND ADJACENT CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated severe thunderstorms appear possible near the
Colorado/Wyoming Front Range and central High Plains this afternoon
and evening.

...20z Update...
No changes are needed to the current D1 Convective Outlook. See
previous discussion below for more information.

..Thornton.. 08/23/2025

.PREV DISCUSSION... /ISSUED 1122 AM CDT Sat Aug 23 2025/

...Front Range/Central High Plains...
A mid/upper-level anticyclone centered over the Southwest and Four
Corners regions will move little today, with ridging extending
northward across much of the Great Basin and Northwest. Modestly
enhanced northwesterly mid-level flow will exist today across the
central Rockies and adjacent High Plains. A moist post-frontal
airmass will remain in place across these areas, with surface
dewpoints generally in the mid to upper 50s. Low cloud cover remains
prevalent across the central High Plains late this morning, which
should continue to hinder destabilization to some extent. Even so,
gradual thunderstorm development should eventually occur over the
higher terrain by late afternoon as persistent low-level upslope
flow aids parcels in reaching their LFCs. This activity should
spread generally south-southeastward through the evening along/near
the I-25 corridor, while posing an isolated threat for mainly hail
due to a combination of modestly steepened lapse rates aloft,
sufficient deep-layer shear, and weak to moderate MLCAPE. Occasional strong/gusty winds may also occur.

...Great Lakes/Midwest...
Isolated thunderstorms should develop along a cold front this
afternoon as it advances eastward across part of the Great
Lakes/Midwest. Warm low/mid-level temperatures in the presence of
generally low/mid 60s surface dewpoints should limit buoyancy and
updraft strength, likely keeping the overall severe potential low.

$$

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ACUS01 KWNS 240041
SWODY1
SPC AC 240040

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0740 PM CDT Sat Aug 23 2025

Valid 240100Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ALONG THE
CENTRAL ROCKIES FRONT RANGE...

...SUMMARY...
Isolated severe thunderstorms remain possible near the
Colorado/Wyoming Front Range and central High Plains this evening.

...01z Update...

Great Basin upper ridge is gradually building north across the
Interior West early this evening. As a result, northwesterly flow
remains firmly established across eastern WY/CO. Scattered
convection has developed beneath this feature with the eastern-most thunderstorms noted along the CO Front Range. Latest diagnostic data
continues to depict a narrow corridor of modest instability along
the Front Range from southeast WY into northeast NM. A few robust
thunderstorms are noted along this corridor but MRMS data suggests
any hail with this activity is likely marginally severe at best.
Will maintain MRGL Risk for isolated-scattered thunderstorms this
evening as cloud-layer shear is more than strong enough for
organized updrafts.

Southeast Lower Michigan: Scattered thunderstorms have developed
along the cold front across southern ON into southeast MI. While
gusty winds, and perhaps some marginally severe hail, may be noted
with these storms for the next hour or so, this activity will
quickly shift into ON. Severe probabilities will not be introduced
for these reasons.

..Darrow.. 08/24/2025

$$

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ACUS01 KWNS 240542
SWODY1
SPC AC 240540

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1240 AM CDT Sun Aug 24 2025

Valid 241200Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF NEW YORK/PENNSYLVANIA AND FROM EASTERN COLORADO TO WESTERN
OKLAHOMA...

...SUMMARY...
A few storms may reach severe thresholds from eastern Colorado into
western Oklahoma this afternoon and evening. Scattered strong-severe
storms are possible across portions of Pennsylvania and New York.
Hail or wind are the expected risks.

...NY/PA...

Early-morning satellite imagery depicts a strong upper trough over
ON/Great Lakes, shifting east-southeast in line with latest model
guidance. Associated surface front is forecast to advance into
western NY/PA by early afternoon before shifting into central
portions of these states by 25/00z. Modest boundary-layer heating is
expected to aid destabilization ahead of the front and convective
temperatures are expected to be breached around 20-21z; although,
deep-layer lapse rates are not expected to be particularly steep
(0-6km values around 6.5 C/km). While CAMs support this with
scattered frontal convection developing around mid afternoon. This
activity could generate locally strong winds, and perhaps some hail.
Main risk will be during the mid afternoon into early evening before
the boundary layer cools after sunset.

...Eastern CO to western OK...

Eastern periphery of Great Basin high will flatten as northwesterly
flow becomes firmly established along the back side of Great
Lakes/OH Valley trough. At the surface, pronounced surface
anticyclone will settle into the northern Plains, ultimately forcing
the leading edge of more continental air into the southern Plains by
the end of the period. Net take is a corridor of low-level warm
advection will become established from southern WY into western OK -
coincident with northwest-southeast frontal orientation. It appears
a few weak disturbances will top the ridge and dig southeast toward
the southern Plains. Each of these features should encourage a
response in the LLJ, which will aid convective development. Elevated
convection may be ongoing at the start of the period across western
NE into northwest KS. A substantial cluster/MCS should propagate
southeast with renewed development later in the period. Rain-cooled
boundary layer will ensure stronger heating is focused across
southeast CO into western OK. Primary concern for isolated severe
will be near this zone of stronger heating/instability. Hail and
wind may accompany this more robust convection.

..Darrow/Weinman.. 08/24/2025

$$

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ACUS01 KWNS 241125
SWODY1
SPC AC 241124

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0624 AM CDT Sun Aug 24 2025

Valid 241300Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS AND NORTHEAST...

...SUMMARY...
A few severe storms are expected this afternoon and evening across
the south-central High Plains spanning eastern Colorado into western
Oklahoma. Scattered strong to severe storms are also possible across
portions of Pennsylvania and New York.

...South-central High Plains..
Within an amplified upper flow regime, a moderately strong belt of northwesterly winds aloft will exist over the region, with one or
more low-amplitude ridge-peripheral disturbances expected to pivot
eastward later today over the central Rockies. A pronounced surface
anticyclone will settle into the northern Plains, forcing the
leading edge of more continental air into the southern Plains by the
end of the period. A corridor of low-level warm advection will
become established from southern Wyoming into western Oklahoma
coincident with the northwest/southeast-oriented front.

Widely scattered generally non-severe elevated storms will probably
persist this morning across western Kansas, with some potential that
the storms may help focus some renewed/increasing convective
potential later today from southwest Kansas into western
Oklahoma/eastern Texas Panhandle. Aided by increasing low-level
upslope flow, other potentially severe storms are expected to
develop across the Colorado Front Range vicinity by late afternoon
and drift southeastward through early/mid-evening. A couple of
supercells will initially be possible, before storms tend to cluster
by evening. Large hail and damaging winds are the primary concerns
regionally, although current thinking is that overall potential
should remain relatively isolated.

...Northeast including New York/Pennsylvania...
A prominent upper-level trough over Ontario/Quebec and Great Lakes
will shift eastward today. An associated surface front is forecast
to advance into western portions of New York/Pennsylvania by early
afternoon. Modest boundary-layer heating is expected to aid
destabilization ahead of the front and convective temperatures
should be breached by around 20-21z; although, deep-layer lapse
rates are not expected to be particularly steep (0-6 km values
around 6.5 C/km). These storms could generate locally strong winds,
and perhaps some hail, with the main risk from mid-afternoon into
early evening.

..Guyer/Kerr.. 08/24/2025

$$

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ACUS01 KWNS 241132
SWODY1
SPC AC 241131

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0631 AM CDT Sun Aug 24 2025

Valid 241300Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS AND NORTHEAST...

...SUMMARY...
A few severe storms are expected this afternoon and evening across
the south-central High Plains spanning eastern Colorado into western
Oklahoma. Scattered strong to severe storms are also possible across
portions of Pennsylvania and New York.

...South-central High Plains..
Within an amplified upper flow regime, a moderately strong belt of northwesterly winds aloft will exist over the region, with one or
more low-amplitude ridge-peripheral disturbances expected to pivot
eastward later today over the central Rockies. A pronounced surface
anticyclone will settle into the northern Plains, forcing the
leading edge of more continental air into the southern Plains by the
end of the period. A corridor of low-level warm advection will
become established from southern Wyoming into western Oklahoma
coincident with the northwest/southeast-oriented front.

Widely scattered generally non-severe elevated storms will probably
persist this morning across western Kansas, with some potential that
the storms may help focus some renewed/increasing convective
potential later today from southwest Kansas into western
Oklahoma/eastern Texas Panhandle. Aided by increasing low-level
upslope flow, other potentially severe storms are expected to
develop across the Colorado Front Range vicinity by late afternoon
and drift southeastward through early/mid-evening. A couple of
supercells will initially be possible, before storms tend to cluster
by evening. Large hail and damaging winds are the primary concerns
regionally, although current thinking is that overall potential
should remain relatively isolated.

...Northeast including New York/Pennsylvania...
A prominent upper-level trough over Ontario/Quebec and Great Lakes
will shift eastward today. An associated surface front is forecast
to advance into western portions of New York/Pennsylvania by early
afternoon. Modest boundary-layer heating is expected to aid
destabilization ahead of the front and convective temperatures
should be breached by around 20-21z; although, deep-layer lapse
rates are not expected to be particularly steep (0-6 km values
around 6.5 C/km). These storms could generate locally strong winds,
and perhaps some hail, with the main risk from mid-afternoon into
early evening.

..Guyer/Kerr.. 08/24/2025

$$

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ACUS01 KWNS 241632
SWODY1
SPC AC 241630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sun Aug 24 2025

Valid 241630Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN/CENTRAL HIGH PLAINS...AND PORTIONS OF NEW YORK AND
PENNSYLVANIA...

...SUMMARY...
A few severe thunderstorms should develop this afternoon and evening
across the southern/central High Plains spanning from eastern
Colorado into western Oklahoma. Scattered strong to severe
thunderstorms are also possible across portions of Pennsylvania and
New York.

...Southern/Central High Plains...
Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This
activity has generally remained sub-severe, but the stronger cores
could be capable of producing occasional hail as they track
southeastward this afternoon given the presence of sufficient MUCAPE
and deep-layer shear. Modestly enhanced mid-level flow is expected
to remain over parts of the central into southern Plains today,
generally from eastern WY/CO into western KS/OK and vicinity,
between a mid/upper-level anticyclone over the Southwest and
mid/upper-level troughing across the Upper Midwest. A surface front
extends from northern CO into western KS. This boundary, along with
outflow from ongoing convection, may serve as foci for robust
thunderstorm development later today.

There is still a fair amount of uncertainty regarding convective
development and evolution this afternoon/evening across the
southern/central High Plains given weak forcing aloft. Modest
low-level upslope flow and orographic effects should encourage at
least isolated thunderstorms to initially develop over the higher
terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The
front/outflow boundary draped from northeast CO into southwest KS
could also serve as a forcing mechanism to aid parcels in reaching
their LFCs. The environment along/south of the front should become
moderately unstable with continued daytime heating, with greater
low-level moisture present across western KS into the OK/TX
Panhandles and western OK.

Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally
enhance 0-1 km SRH. It appears possible that a supercell or two
could develop near the front later today and track
south-southeastward in a favorable northwesterly mid-level flow
regime. Isolated large hail would probably be the main threat if a
supercell can be sustained, with perhaps a tornado also possible
where low-level flow can remain backed to southeasterly near the
front. Some guidance suggests a cluster or two may eventually emerge
this evening across eastern CO and/or southwest KS, but this
potential remains highly uncertain. Mesoscale trends will be
monitored for a zone of more focused severe potential and possible
outlook upgrade.

...New York/Pennsylvania...
An amplified upper trough/low over Ontario and extending southward
into the Great Lakes/Midwest is forecast to gradually shift eastward
today. A related surface cold front will also advance
east-southeastward through the period across parts of the Northeast
and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly
moist low-level airmass ahead of the front will promote weak to
locally moderate instability this afternoon, especially across parts
of PA/NY. Current expectations are for thunderstorms to develop
along/near the front through the afternoon across western PA/NY.
While mid-level lapse rates are forecast to remain poor, which will
likely limit updraft strength, sufficient deep-layer shear should be
present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and
perhaps marginally severe hail as they spread eastward across
central PA and central/northern NY through early evening. This
activity should weaken with eastward extent as it encounters a less
unstable airmass.

..Gleason/Moore.. 08/24/2025

$$

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ACUS01 KWNS 242000
SWODY1
SPC AC 241959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Sun Aug 24 2025

Valid 242000Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO
INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA
PANHANDLE...

...SUMMARY...
A few severe thunderstorms are expected this afternoon and evening
across the southern/central High Plains spanning from eastern
Colorado into western Oklahoma. Scattered strong to severe
thunderstorms are also possible across portions of Pennsylvania and
New York.

...20z Update...
An upgrade to Slight was made with this update in eastern
Colorado/western Kansas. Thermodynamics and shear profiles are
favorable for supercell development. Recent development on radar
suggests attempts are ongoing across portions of eastern Colorado
near the Palmer Divide and near Colorado Springs. Any more discrete
supercells that can be maintained will pose a risk for large hail,
and as such a 15% was added with this update. See MCD#2009 for more information.

..Thornton.. 08/24/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/

...Southern/Central High Plains...
Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This
activity has generally remained sub-severe, but the stronger cores
could be capable of producing occasional hail as they track
southeastward this afternoon given the presence of sufficient MUCAPE
and deep-layer shear. Modestly enhanced mid-level flow is expected
to remain over parts of the central into southern Plains today,
generally from eastern WY/CO into western KS/OK and vicinity,
between a mid/upper-level anticyclone over the Southwest and
mid/upper-level troughing across the Upper Midwest. A surface front
extends from northern CO into western KS. This boundary, along with
outflow from ongoing convection, may serve as foci for robust
thunderstorm development later today.

There is still a fair amount of uncertainty regarding convective
development and evolution this afternoon/evening across the
southern/central High Plains given weak forcing aloft. Modest
low-level upslope flow and orographic effects should encourage at
least isolated thunderstorms to initially develop over the higher
terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The
front/outflow boundary draped from northeast CO into southwest KS
could also serve as a forcing mechanism to aid parcels in reaching
their LFCs. The environment along/south of the front should become
moderately unstable with continued daytime heating, with greater
low-level moisture present across western KS into the OK/TX
Panhandles and western OK.

Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally
enhance 0-1 km SRH. It appears possible that a supercell or two
could develop near the front later today and track
south-southeastward in a favorable northwesterly mid-level flow
regime. Isolated large hail would probably be the main threat if a
supercell can be sustained, with perhaps a tornado also possible
where low-level flow can remain backed to southeasterly near the
front. Some guidance suggests a cluster or two may eventually emerge
this evening across eastern CO and/or southwest KS, but this
potential remains highly uncertain. Mesoscale trends will be
monitored for a zone of more focused severe potential and possible
outlook upgrade.

...New York/Pennsylvania...
An amplified upper trough/low over Ontario and extending southward
into the Great Lakes/Midwest is forecast to gradually shift eastward
today. A related surface cold front will also advance
east-southeastward through the period across parts of the Northeast
and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly
moist low-level airmass ahead of the front will promote weak to
locally moderate instability this afternoon, especially across parts
of PA/NY. Current expectations are for thunderstorms to develop
along/near the front through the afternoon across western PA/NY.
While mid-level lapse rates are forecast to remain poor, which will
likely limit updraft strength, sufficient deep-layer shear should be
present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and
perhaps marginally severe hail as they spread eastward across
central PA and central/northern NY through early evening. This
activity should weaken with eastward extent as it encounters a less
unstable airmass.

$$

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ACUS01 KWNS 250101
SWODY1
SPC AC 250100

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Sun Aug 24 2025

Valid 250100Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
COLORADO TO THE TX/OK PANHANDLE AND WESTERN OKLAHOMA...

...SUMMARY...
A few severe thunderstorms are expected to continue evening across
the southern/central High Plains spanning from eastern Colorado into
western Oklahoma. Scattered strong to severe thunderstorms are also
possible for a few more hours across portions of Pennsylvania and
New York.

...Discussion...
Several thunderstorms are ongoing across southeast Colorado where a
few hail and wind reports have been received. These storms are
expected to congeal into larger clusters. However, the severe threat
should only last for a few more hours while moderate instability
remains. However, decreasing instability and increasing inhibition
should limit the overall threat by later this evening. See MCD 2012
for additional discussion of this threat area.

A few severe storms have developed across western Oklahoma this
evening where 1000 to 1500 J/kg MLCAPE and moderate shear is
present. These storms should persist for at least a few more hours
with a threat for large hail and severe wind gusts. Increasing
inhibition should reduce the threat by later this evening. See MCD
2011 for additional discussion of the near-term threat across this
area.

..Bentley.. 08/25/2025

$$

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ACUS01 KWNS 250601
SWODY1
SPC AC 250559

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Mon Aug 25 2025

Valid 251200Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHERN ARIZONA...

...SUMMARY...
Isolated severe gusts are possible over parts of south-central
Arizona this afternoon. Otherwise, potential for severe storms is
low across the remainder of the continental U.S.

...Synopsis...
A large upper-level trough will continue to amplify across the
eastern CONUS today. High pressure, currently analyzed across the
northern Plains early this morning will expand slowly southward
through the day which will push the polar front off the Atlantic
coast and perhaps into the Gulf. A persistent upper-level ridge will
exist across the Southwest and into the Great Basin/Rocky Mountains.
Beneath this ridge, a continued monsoon push will result in
widespread thunderstorm activity this afternoon/evening.

...Southern Arizona...
Monsoon thunderstorms are forecast to develop this afternoon/evening
across much of the Southwest amid weak to moderate instability
(1000-1500 J/kg MLCAPE) as temperatures cool aloft. A belt of
stronger mid-level southeasterly flow (20 to 25 knots) is forecast
to overspread the region and provide ample shear for some multicell
storm clusters. Initial storms which are expected to form across the
higher terrain in southeast Arizona may result in congealing outflow
with a damaging wind threat as storms move generally northwestward
through the evening.

..Bentley/Weinman.. 08/25/2025

$$

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ACUS01 KWNS 251240
SWODY1
SPC AC 251238

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Mon Aug 25 2025

Valid 251300Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
ARIZONA...

...SUMMARY...
Isolated severe wind gusts are possible over parts of south-central
Arizona this afternoon through early evening. Otherwise, the
potential for severe storms is low across the remainder of the
continental U.S.

..Synopsis...
A large upper-level trough will continue to amplify across the
eastern CONUS today. High pressure, currently analyzed across the
northern Plains early this morning will expand slowly southward
through the day which will push the polar front off the Atlantic
coast and perhaps into the Gulf. A persistent upper-level ridge will
exist across the Southwest and into the Great Basin/Rocky Mountains.
Beneath this ridge, a continued monsoon push will result in
widespread thunderstorm activity this afternoon/evening.

...Southern Arizona...
Thunderstorms are forecast to develop this afternoon/evening across
much of the Southwest amid weak to moderate instability (1000-1500
J/kg MLCAPE) as temperatures cool aloft. A belt of stronger
mid-level southeasterly flow (20-25 kt) is forecast to overspread
the region and provide ample shear for some multicell storm
clusters. Initial storms which are expected to form across the
higher terrain in southeast Arizona may result in congealing outflow
with a damaging wind threat as storms move generally
west-northwestward through the evening.

..Guyer/Kerr.. 08/25/2025

$$

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ACUS01 KWNS 251632
SWODY1
SPC AC 251631

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1131 AM CDT Mon Aug 25 2025

Valid 251630Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
ARIZONA...

...SUMMARY...
Isolated severe wind gusts are possible over parts of south-central
Arizona this afternoon through early evening. Otherwise, the
potential for severe storms is low across the remainder of the
continental U.S.

...Synopsis...
A large upper trough will remain over the eastern CONUS today, as
several embedded shortwave troughs progress within its southern
periphery. Extensive upper ridging that currently extends from the
southern Plains into the northern Intermountain West is forecast to
remain largely in place. Some dampening may occur along the
northwestern periphery of this ridging as a slow-moving vorticity
maximum continues northeastward from the CO/OR/NV border vicinity
into more of eastern OR. Ample monsoonal moisture exists beneath
this ridging, contributing to scattered to numerous thunderstorms
from the southern/central Rockies westward across the Southwest and
much of the Great Basin. Limited vertical shear and weak buoyancy
will mitigate the severe potential across the majority of the
region. The only exceptions are across central Rockies and immediate
foothills, and portions of southern AZ.

...Southern AZ...
Ample monsoonal moisture is in place across the region, evidenced by
PW values of 1.66 and 1.83 inches from the Phoenix and Yuma 12Z
soundings, respectively. Filtered diurnal heating within this moist
airmass will support modest buoyancy and afternoon thunderstorm
development. A belt of stronger mid-level southeasterly flow (20-25
kt) is forecast to overspread the region this afternoon, providing
ample shear for some multicell storm clusters. Initial storms which
are expected to form across the higher terrain in southeast Arizona
may result in congealing outflow with a damaging wind threat as
storms move generally west-northwestward through the evening.

...Central Rockies...
Thunderstorm development is expected across the high terrain by the
early afternoon. Poor lapse rates and cooler temperatures will keep
buoyancy will be modest, likely limiting overall updraft strength
and tempering the severe potential. Even so, moderate northwesterly
flow aloft will support long hodographs and the potential for some
storm organization if updrafts can become sufficiently deep. An
instance or two of hail is possible with any stronger, more
long-lived storms.

..Mosier/Moore.. 08/25/2025

$$

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ACUS01 KWNS 251959
SWODY1
SPC AC 251957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Mon Aug 25 2025

Valid 252000Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER SOUTHERN
ARIZONA...

...SUMMARY...
Isolated severe wind gusts are possible over parts of south-central
Arizona this afternoon through early evening. Otherwise, the
potential for severe storms is low across the remainder of the
continental U.S.

...20z Update...
Scattered storms are currently developing over parts of southern AZ
and MX ahead of a weak MCV. Additional development is expected the
remainder of the afternoon into this evening. Limited buoyancy
(MLCAPE ~1000 J/kg) will support multicell updrafts atop fairly dry
low-levels. A few of the semi-organized storm clusters could support
stronger downdrafts with damaging gust potential. Minor changes were
made to the edges of MRGL risk area, see MCD #2014 for short-term
information. Elsewhere, scattered storms are expected over the
central and western CONUS today/tonight. Limited buoyancy and
vertical shear will keep the severe risk low. See the previous
discussion.

..Lyons.. 08/25/2025

.PREV DISCUSSION... /ISSUED 1131 AM CDT Mon Aug 25 2025/

...Synopsis...
A large upper trough will remain over the eastern CONUS today, as
several embedded shortwave troughs progress within its southern
periphery. Extensive upper ridging that currently extends from the
southern Plains into the northern Intermountain West is forecast to
remain largely in place. Some dampening may occur along the
northwestern periphery of this ridging as a slow-moving vorticity
maximum continues northeastward from the CO/OR/NV border vicinity
into more of eastern OR. Ample monsoonal moisture exists beneath
this ridging, contributing to scattered to numerous thunderstorms
from the southern/central Rockies westward across the Southwest and
much of the Great Basin. Limited vertical shear and weak buoyancy
will mitigate the severe potential across the majority of the
region. The only exceptions are across central Rockies and immediate
foothills, and portions of southern AZ.

...Southern AZ...
Ample monsoonal moisture is in place across the region, evidenced by
PW values of 1.66 and 1.83 inches from the Phoenix and Yuma 12Z
soundings, respectively. Filtered diurnal heating within this moist
airmass will support modest buoyancy and afternoon thunderstorm
development. A belt of stronger mid-level southeasterly flow (20-25
kt) is forecast to overspread the region this afternoon, providing
ample shear for some multicell storm clusters. Initial storms which
are expected to form across the higher terrain in southeast Arizona
may result in congealing outflow with a damaging wind threat as
storms move generally west-northwestward through the evening.

...Central Rockies...
Thunderstorm development is expected across the high terrain by the
early afternoon. Poor lapse rates and cooler temperatures will keep
buoyancy will be modest, likely limiting overall updraft strength
and tempering the severe potential. Even so, moderate northwesterly
flow aloft will support long hodographs and the potential for some
storm organization if updrafts can become sufficiently deep. An
instance or two of hail is possible with any stronger, more
long-lived storms.

$$

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ACUS01 KWNS 260047
SWODY1
SPC AC 260045

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 PM CDT Mon Aug 25 2025

Valid 260100Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A SMALL
PORTION OF SOUTH-CENTRAL ARIZONA....

...SUMMARY...
Isolated severe wind gusts are possible over parts of south-central
Arizona for a few more hours this evening. Otherwise, the potential
for severe storms is low across the remainder of the continental
U.S.

...Discussion...
A cluster of storms has produced some damaging winds across
south-central Arizona. As the boundary layer cools this evening,
expect these storms to weaken. However, the threat for isolated
damaging winds will persist for a few more hours amid 1000+ J/kg
DCAPE and steep low/mid level lapse rates.

Elsewhere, diurnal thunderstorms across the western CONUS will wane
this evening. Additional storms are expected to develop from the TX
Panhandle to western Oklahoma tonight, but weak instability should
limit any severe weather potential from this activity.

..Bentley.. 08/26/2025

$$

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ACUS01 KWNS 260559
SWODY1
SPC AC 260557

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Tue Aug 26 2025

Valid 261200Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe storms are not expected across the continental U.S. on
Tuesday.

...Synopsis...
An expansive upper-level trough will be present across the eastern
CONUS today. At the surface, a cool, dry airmass and high pressure
will dominate most of the eastern CONUS, limiting thunderstorm
potential. Widespread monsoonal thunderstorm activity will occur
across much of the western CONUS.

...Southern Arizona...
Weak instability is forecast across southern Arizona with sufficient
heating for thunderstorm development this afternoon. Mid-level flow
around 20 knots Tuesday morning will weaken slightly by the
afternoon. This belt of enhanced flow may provide enough shear for a
stronger multicell thunderstorm with an isolated damaging wind
threat. However, overall, expect storm organization to be limited
with mostly sub-severe convection due to weaker instability and
shear than Monday.

Given the number of storms across the western CONUS today, isolated
damaging wind gusts may be possible. However, a more organized
region/threat is not apparent.

..Bentley/Weinman.. 08/26/2025

$$

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ACUS01 KWNS 261249
SWODY1
SPC AC 261248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Tue Aug 26 2025

Valid 261300Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe storms are not expected across the continental U.S.
today.

...Synopsis...
An expansive upper-level trough will persist across the eastern
CONUS today, where a cool, dry airmass and high pressure
will be prevalent and limit thunderstorm potential aside from
Florida. Monsoon-related scattered thunderstorms will be common
across much of the non-coastal West.

...Southern Arizona/Lower Colorado River Valley...
A northward-moving mid-level impulse/MCV will spread from the Lower
Colorado River Valley/northern Arizona this morning into Utah,
allowing for subsequent clearing/heating across southern Arizona
toward the Lower Colorado River Valley. Thunderstorms will again
develop and increase this afternoon especially in vicinity of higher
terrain. A few instances of strong thunderstorm winds/wet
microbursts could occur regionally this afternoon into evening, but
the overall potential is expected to remain quite isolated and
marginal overall.

..Guyer/Kerr.. 08/26/2025

$$

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ACUS01 KWNS 261622
SWODY1
SPC AC 261620

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1120 AM CDT Tue Aug 26 2025

Valid 261630Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms appear unlikely across the contiguous
United States through tonight.

...Synopsis and Discussion...
Large-scale upper troughing will remain over the eastern CONUS
today, with surface high pressure dominating much of the
central/eastern CONUS. Isolated thunderstorms may occur this
afternoon and evening along/south of a surface cold front across
parts of the FL Peninsula and central/south TX. However, weak flow
aloft and related deep-layer shear should preclude an organized
severe threat across these regions with this activity.

Scattered to numerous thunderstorms are expected to develop today
across much of the interior western CONUS, as upper ridging weakens
over the Southwest and multiple weak mid-level perturbations move north-northeastward across the Sierras and Great Basin. Ongoing
thunderstorms this morning across the Central Valley in CA will be
in a relatively more favorable thermodynamic environment, with
modestly steepened mid-level lapse rates compared to locations
farther east over the Great Basin potentially supporting small hail
with the stronger cores. Still, shear is expected to remain modest
at best with westward extent, which should limit updraft
organization and overall severe potential.

Isolated strong/gusty winds may also occur with any convection that
can develop over parts of interior southern CA into the lower CO
River Valley, particularly where steepened low-level lapse rates can
develop with daytime heating/mixing of the boundary layer away from
ongoing cloud cover. The potential for a more concentrated corridor
of severe winds still appears low across this area, as it will be in
a generally subsident regime behind a weak mid-level shortwave
trough advancing northward from southern NV across the Great Basin
this afternoon.

Finally, an occasional/very isolated strong to severe gust cannot be
ruled out across the Four Corners region this afternoon, as
convection develops along the Mogollon Rim in northern AZ and
subsequently spreads north-northeastward in tandem with a weak
mid-level shortwave trough. Even so, deep-layer shear appears too
marginal to include low severe wind probabilities with this update.

..Gleason/Moore.. 08/26/2025

$$

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ACUS01 KWNS 261958
SWODY1
SPC AC 261956

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Tue Aug 26 2025

Valid 262000Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms appear unlikely across the contiguous
United States through tonight.

...20Z Update...
Isolated strong storms remain possible in the Four Corners vicinity
this afternoon. Observed 18Z soundings from Tucson and Flagstaff
indicate relatively poor mid-level lapse rates and marginal
effective shear. Areas of stronger surface heating could promote
stronger outflow winds, but organized severe storms are still
unlikely. Only minor modifications were made to the general thunder
area based on current observations. Additional forecast details are
in the previous discussion below.

..Wendt.. 08/26/2025

.PREV DISCUSSION... /ISSUED 1120 AM CDT Tue Aug 26 2025/

...Synopsis and Discussion...
Large-scale upper troughing will remain over the eastern CONUS
today, with surface high pressure dominating much of the
central/eastern CONUS. Isolated thunderstorms may occur this
afternoon and evening along/south of a surface cold front across
parts of the FL Peninsula and central/south TX. However, weak flow
aloft and related deep-layer shear should preclude an organized
severe threat across these regions with this activity.

Scattered to numerous thunderstorms are expected to develop today
across much of the interior western CONUS, as upper ridging weakens
over the Southwest and multiple weak mid-level perturbations move north-northeastward across the Sierras and Great Basin. Ongoing
thunderstorms this morning across the Central Valley in CA will be
in a relatively more favorable thermodynamic environment, with
modestly steepened mid-level lapse rates compared to locations
farther east over the Great Basin potentially supporting small hail
with the stronger cores. Still, shear is expected to remain modest
at best with westward extent, which should limit updraft
organization and overall severe potential.

Isolated strong/gusty winds may also occur with any convection that
can develop over parts of interior southern CA into the lower CO
River Valley, particularly where steepened low-level lapse rates can
develop with daytime heating/mixing of the boundary layer away from
ongoing cloud cover. The potential for a more concentrated corridor
of severe winds still appears low across this area, as it will be in
a generally subsident regime behind a weak mid-level shortwave
trough advancing northward from southern NV across the Great Basin
this afternoon.

Finally, an occasional/very isolated strong to severe gust cannot be
ruled out across the Four Corners region this afternoon, as
convection develops along the Mogollon Rim in northern AZ and
subsequently spreads north-northeastward in tandem with a weak
mid-level shortwave trough. Even so, deep-layer shear appears too
marginal to include low severe wind probabilities with this update.

$$

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ACUS01 KWNS 270050
SWODY1
SPC AC 270049

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 PM CDT Tue Aug 26 2025

Valid 270100Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms appear unlikely across the contiguous
United States through tonight.

...Discussion...
Mostly unorganized thunderstorm activity has been prevalent across
the western CONUS this evening. A few stronger storms and isolated
stronger cores have been present. However, the severe potential has
been limited and will remain so through the overnight period.

..Bentley.. 08/27/2025

$$

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ACUS01 KWNS 270557
SWODY1
SPC AC 270556

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1256 AM CDT Wed Aug 27 2025

Valid 271200Z - 281200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
The potential for severe storms appears to be low across the
continental U.S. today, though a few stronger storms are possible
across parts of the Upper Midwest and Colorado Front Range where
locally gusty winds and small hail are possible.

...Synopsis...
A broad upper-level trough will be present across the eastern CONUS
today with weak ridging across the western CONUS. Surface high
pressure will weaken slightly and shift east across the Appalachians
into the Mid-Atlantic/Carolinas. A cold front along the Gulf Coast
will extend into the Central Plains.

...Upper Midwest...
A region of moderate instability and shear is forecast to develop
across southern Minnesota this afternoon. A lead shortwave trough
(currently across north Dakota) is expected to move through southern
Minnesota around mid-day with weak height rises and subsidence in
its wake. However, by the evening, an additional shortwave trough
(traversing the western edge of the broader trough) may result in
isolated storm development by late afternoon/early evening. Some
forecast sounding, particularly the NAM, would support a few strong
to isolated severe storms with a threat for large hail. However,
consensus guidance is not as unstable and therefore, any severe
threat may remain mostly isolated. Therefore, no severe weather
probabilities will be included at this time.

...Central High Plains into western Kansas...
Thunderstorms across the central High Plains may congeal into a
cluster as they move into western Kansas this evening. A belt of
stronger mid-level flow (35 to 45 knots) on the southwest periphery
of the large-scale trough will provide favorable deep-layer shear
across the region. However, despite the favorable shear, weak
mid-level lapse rates will limit overall instability. A few stronger
storms capable of damaging winds will be possible, but this threat
is expected to be too low/limited to warrant severe weather
probabilities.

..Bentley/Weinman.. 08/27/2025

$$

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ACUS01 KWNS 271254
SWODY1
SPC AC 271253

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Wed Aug 27 2025

Valid 271300Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
COLORADO...

...SUMMARY...
Some strong to locally severe storms may occur across eastern
Colorado and the central High Plains late this afternoon and early
evening.

...Eastern Colorado/Central High Plains...
Prevalent cloud cover and some lingering mostly light precipitation
should eventually abate later this afternoon, with thunderstorms
expected to develop/increase initially over the mountains by around mid-afternoon. These storms will spread east-southeastward toward
the instability axis across the adjacent High Plains through early
evening. Moderately strong mid-level flow could support some
semi-organized storms, and a couple of clusters could evolve by
evening. Localized instances of marginally severe hail and/or wind
could occur, although locally heavy rainfall may be more of a
prevalent concern.

...Upper Midwest...
A region of moderate instability is forecast to develop from eastern
South Dakota into southern Minnesota this afternoon. But this will
be in the wake of a southeastward-moving shortwave trough, with weak
height rises and subsidence in its wake. Nonetheless, isolated storm development may occur by late afternoon/early evening, and a few
strong storms are conceivable.

..Guyer/Kerr.. 08/27/2025

$$

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ACUS01 KWNS 271629
SWODY1
SPC AC 271628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Wed Aug 27 2025

Valid 271630Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL HIGH PLAINS AND UPPER MIDWEST...

...SUMMARY...
Isolated strong to severe thunderstorms may occur across parts of
the central High Plains and Upper Midwest this afternoon and early
evening.

...Central High Plains...
Upper ridging should remain suppressed over TX today, with modest
mid-level westerly flow persisting across the central Plains. Late
morning visible satellite imagery shows some clearing across eastern
CO, which should aid in diurnal destabilization this afternoon.
Gradual low-level moisture return is forecast to continue today
across the central High Plains, generally along and east of a weak
lee trough/low where low to mid 60s surface dewpoints are present.
With scattered to numerous thunderstorms over much of the Southwest
and southern/central Rockies yesterday, there is not a notable EML
present over the central High Plains today (reference 12Z observed
DDC sounding). This should temper the degree of instability that can
develop through the afternoon to some extent. Even so, around
500-1500 J/kg of MLCAPE appears plausible with additional diurnal
heating of the modestly moistened low-level airmass.

Weak low-level southerly flow will veer to westerly and gradually
strengthen with height through mid/upper levels, supporting around
25-40 kt of deep-layer shear. Thunderstorms are expected to develop
initially along/near the Front Range this afternoon, before
spreading slowly east-southeastward across eastern CO and parts of
western KS through the evening. Isolated severe hail may occur with
the strongest cores/marginal supercell structures, until gradual
outflow/cold pool amalgamation encourages one or more clusters with
a greater threat for occasional strong to severe gusts. Based on
latest observational and short-term guidance trends, the Marginal
Risk has been expanded to include more of eastern CO and western KS.
Mainly elevated thunderstorms will likely continue overnight into central/eastern KS in a modest low-level warm advection regime.
However, confidence in a continued hail/wind threat with this
activity remains low at this time.

...Upper Midwest...
On the western side of a large-scale upper trough over eastern
Canada and the Atlantic Coast states, modestly enhanced
northwesterly mid-level flow is forecast to persist through much of
the period. A weak embedded shortwave trough moving across southern
MN and vicinity late this morning suggests modest large-scale
subsidence in its wake. This casts some uncertainty on the possible
development of isolated to scattered thunderstorms later today
along/south of a weak surface trough across eastern SD into
central/southern MN. Even so, most guidance suggests at least
isolated thunderstorms will form across this region by late
afternoon/early evening. Cool mid-level temperatures and generally long/straight hodographs aloft suggest some threat for severe hail
with any of the stronger cores that can be sustained. Have therefore
added a focused Marginal Risk across parts of eastern SD into
southern MN for this potential.

..Gleason/Moore.. 08/27/2025

$$

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ACUS01 KWNS 271955
SWODY1
SPC AC 271954

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Wed Aug 27 2025

Valid 272000Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE
CENTRAL HIGH PLAINS AND THE UPPER MIDWEST...

...SUMMARY...
Isolated strong to severe thunderstorms may occur across parts of
the central High Plains and Upper Midwest this afternoon and early
evening.

...20Z Update...
The forecast remains on track with only minor adjustments to the
general thunderstorm forecast. See the previous discussion for
additional information.

..Wendt.. 08/27/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Aug 27 2025/

...Central High Plains...
Upper ridging should remain suppressed over TX today, with modest
mid-level westerly flow persisting across the central Plains. Late
morning visible satellite imagery shows some clearing across eastern
CO, which should aid in diurnal destabilization this afternoon.
Gradual low-level moisture return is forecast to continue today
across the central High Plains, generally along and east of a weak
lee trough/low where low to mid 60s surface dewpoints are present.
With scattered to numerous thunderstorms over much of the Southwest
and southern/central Rockies yesterday, there is not a notable EML
present over the central High Plains today (reference 12Z observed
DDC sounding). This should temper the degree of instability that can
develop through the afternoon to some extent. Even so, around
500-1500 J/kg of MLCAPE appears plausible with additional diurnal
heating of the modestly moistened low-level airmass.

Weak low-level southerly flow will veer to westerly and gradually
strengthen with height through mid/upper levels, supporting around
25-40 kt of deep-layer shear. Thunderstorms are expected to develop
initially along/near the Front Range this afternoon, before
spreading slowly east-southeastward across eastern CO and parts of
western KS through the evening. Isolated severe hail may occur with
the strongest cores/marginal supercell structures, until gradual
outflow/cold pool amalgamation encourages one or more clusters with
a greater threat for occasional strong to severe gusts. Based on
latest observational and short-term guidance trends, the Marginal
Risk has been expanded to include more of eastern CO and western KS.
Mainly elevated thunderstorms will likely continue overnight into central/eastern KS in a modest low-level warm advection regime.
However, confidence in a continued hail/wind threat with this
activity remains low at this time.

...Upper Midwest...
On the western side of a large-scale upper trough over eastern
Canada and the Atlantic Coast states, modestly enhanced
northwesterly mid-level flow is forecast to persist through much of
the period. A weak embedded shortwave trough moving across southern
MN and vicinity late this morning suggests modest large-scale
subsidence in its wake. This casts some uncertainty on the possible
development of isolated to scattered thunderstorms later today
along/south of a weak surface trough across eastern SD into
central/southern MN. Even so, most guidance suggests at least
isolated thunderstorms will form across this region by late
afternoon/early evening. Cool mid-level temperatures and generally long/straight hodographs aloft suggest some threat for severe hail
with any of the stronger cores that can be sustained. Have therefore
added a focused Marginal Risk across parts of eastern SD into
southern MN for this potential.

$$

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ACUS01 KWNS 280055
SWODY1
SPC AC 280053

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 PM CDT Wed Aug 27 2025

Valid 280100Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated strong to severe thunderstorms remain possible across parts
of the central High Plains early this evening.

...01z Update...

Scattered convection persists across much of the western United
States early this evening, primarily driven by strong boundary-layer
heating. Much of this activity will gradually weaken as the evening
progresses. A corridor of modest instability persists across the
central High Plains and a few small clusters are noted across
eastern Colorado into southwest Kansas. Weak low-level warm
advection will maintain this activity into the mid-evening hours,
with some upscale growth possible downstream later tonight as LLJ
strengthens. Even so, most of this convection should remain
sub-severe.

..Darrow.. 08/28/2025

$$

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ACUS01 KWNS 280538
SWODY1
SPC AC 280537

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1237 AM CDT Thu Aug 28 2025

Valid 281200Z - 291200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE SOUTHERN PLAINS INTO THE ARKLATEX...AND ACROSS EASTERN
COLORADO...

...SUMMARY...
Strong thunderstorms, with an isolated severe wind threat, are
possible across parts of the southern Plains into the Arklatex this
afternoon and evening. Isolated severe thunderstorms are also
possible across eastern Colorado.

...Southern Plains/Arklatex...

Weak short-wave trough is evident in water-vapor imagery over the
central High Plains. This feature is digging southeast in line with
latest model guidance. A substantial amount of convection is
currently noted just ahead of this feature across western into south
central KS. This activity should gradually grow upscale through
sunrise as LLJ veers into northeast OK by late morning. Associated
rain-cooled boundary layer air mass will reinforce a surface
boundary currently draped across the southern Plains. Latest model
guidance suggests strong surface heating will contribute to
substantial destabilization across much of southern OK into
northeast TX, immediately south of the front. While mid-level
temperatures are seasonally warm (-4C at 500mb), and lapse rates are
not that steep, some risk for an isolated wind gusts or marginally
severe hail can be expected with the more robust convection.
Deepening northwesterly flow will encourage an MCS to spread from
northeast OK into southern AR, and the southwestern flank of this
activity will be more influenced by higher buoyancy along the Red
River corridor.

...Eastern CO...

Large-scale pattern is not expected to change appreciably during the
day1 period as upper ridging will hold across the southern/central
Rockies. While mid-level flow is not that strong across CO,
low-level upslope flow is expected to contribute to scattered
thunderstorm development as boundary layer heats later this
afternoon. This activity will spread southeast with an attendant
risk for at least gusty winds and isolated hail.

..Darrow/Weinman.. 08/28/2025

$$

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ACUS01 KWNS 281251
SWODY1
SPC AC 281249

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 AM CDT Thu Aug 28 2025

Valid 281300Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHEAST
OKLAHOMA AND ARKLATEX...

...SUMMARY...
Strong thunderstorms, with an isolated hail and severe wind threat,
are possible across parts of southern Oklahoma and northern Texas to
the Arklatex this afternoon and evening. Isolated severe
thunderstorms will also be possible across eastern Colorado and the
adjacent High Plains.

...Southern Oklahoma/North Texas to ArkLaTex...
Showers/thunderstorms are prevalent this morning across
northern/eastern Oklahoma into the Ozarks to the north-northeast of
a warm front. Within a belt of moderately strong northwesterly flow
aloft, a shortwave trough will continue to dig southeastward from
the south-central Plains toward the Ozarks by this evening. Related
dynamical response and the early day convection will shunt the front
southward later today, with ample heating/moderate destabilization
on the southwest flank of this boundary.

While mid-level temperatures are seasonally warm (-4C at 500 mb),
and lapse rates are not that steep, severe hail and damaging wind
gusts can be expected with the more robust convection as general intensification occurs by mid/late afternoon. A few initial
supercells may occur, and some tornado risk could also exist with
convection immediately along the boundary and east of the weak
surface front. Clustering/upscale-quasi-linear growth should occur
by early evening as storms progress southeastward and continue to
pose a damaging wind risk for a time this evening.

...Eastern Colorado and adjacent High Plains...
The large-scale pattern is not expected to change appreciably as
upper ridging will hold across the southern/central Rockies. While
mid-level flow is not that strong across Colorado, low-level upslope
flow is expected to contribute to scattered thunderstorm development
as boundary layer heats later this afternoon. This activity will
spread southeastward with an attendant risk for isolated severe hail
and gusty winds.

..Guyer/Kerr.. 08/28/2025

$$

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ACUS01 KWNS 281618
SWODY1
SPC AC 281616

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1116 AM CDT Thu Aug 28 2025

Valid 281630Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHEAST
OKLAHOMA AND ARKLATEX...

...SUMMARY...
Strong thunderstorms, with an isolated hail and severe wind threat,
are possible across parts of southern Oklahoma and northern Texas to
the Arklatex this afternoon and evening. Isolated severe
thunderstorms will also be possible across eastern Colorado and the
adjacent High Plains.

...Southern Oklahoma/North Texas to ArkLaTex...
Widespread showers and thunderstorms are ongoing from
central/eastern OK southeastward across northern/central AR and into northern/central MS. This area of precipitation is occurring along
and north of a warm-front-like boundary that extends from the TX
Panhandle southeastward through south-central OK into northeast TX.
General expectation is for the ongoing storms to persist throughout
the day, supported mainly by modest mid-level southwesterlies and
associated warm-air advection across the boundary. Additionally,
this boundary will likely sharpen throughout the day as the precipitation/cloudiness continue north of the boundary, and
warm/moist conditions persist south of the boundary.

The ongoing elevated storms across southeast OK will likely continue southeastward, likely resulting in a small corridor where diurnal
heating is possible in the vicinity of the warm front, but ahead of
the slowly progressing outflow moving across central/south-central
OK. This heating of the moist airmass in place could result in a
corridor of moderate to strong buoyancy, despite relatively warm
temperatures aloft and poor lapse rates. This buoyancy coupled with
moderate deep-layer vertical shear provided by the moderate
northwesterly flow aloft could result in a few strong and organized
updrafts. Given current trends, a reintensification of cells along
the outflow appears to be the most likely convective evolution, with
the resulting linear mode favoring damaging gusts as the primary
risk. That being said, given continued low-level moisture
convergence near the warm front, more discrete development ahead of
the outflow is also a possibility. Any more discrete storms could
become supercellular, with a low-probability risk for a tornado
and/or hail, particularly near the surface boundary.

Additional development is possible this afternoon along the western
edge of the outflow across southwest OK and the TX Big Country/Low
Rolling Plains. A few stronger storms capable of damaging gusts are
possible in these areas.

...Central High Plains...
Low-level upslope flow is expected to contribute to scattered
thunderstorm development the as boundary layer heats across the
central High Plains later this afternoon. Moderate mid-level flow
atop low-level easterlies will result in around 35-40 kt of
effective bulk shear, which is strong enough to support organized
storm structures. This activity will spread southeastward towards
the lower terrain over time, with an attendant risk for isolated
severe hail and gusty winds.

..Mosier/Moore.. 08/28/2025

$$

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ACUS01 KWNS 281944
SWODY1
SPC AC 281943

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0243 PM CDT Thu Aug 28 2025

Valid 282000Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHEAST OKLAHOMA
INTO THE ARKLATEX...

...SUMMARY...
Strong thunderstorms, with an isolated hail and severe wind threat,
are possible across parts of southern Oklahoma and northern Texas to
the Arklatex this afternoon and evening. Isolated severe
thunderstorms will also be possible across eastern Colorado and the
adjacent High Plains.

...20Z Update...
Based on current observations and convective trends, changes were
made to the general thunderstorm forecast. The Slight risk in the
ArkLaTex vicinity was also trimmed behind ongoing convection. The
remainder of the forecast remains on track. Additional information
is found in the previous discussion below.

..Wendt.. 08/28/2025

.PREV DISCUSSION... /ISSUED 1116 AM CDT Thu Aug 28 2025/

...Southern Oklahoma/North Texas to ArkLaTex...
Widespread showers and thunderstorms are ongoing from
central/eastern OK southeastward across northern/central AR and into northern/central MS. This area of precipitation is occurring along
and north of a warm-front-like boundary that extends from the TX
Panhandle southeastward through south-central OK into northeast TX.
General expectation is for the ongoing storms to persist throughout
the day, supported mainly by modest mid-level southwesterlies and
associated warm-air advection across the boundary. Additionally,
this boundary will likely sharpen throughout the day as the precipitation/cloudiness continue north of the boundary, and
warm/moist conditions persist south of the boundary.

The ongoing elevated storms across southeast OK will likely continue southeastward, likely resulting in a small corridor where diurnal
heating is possible in the vicinity of the warm front, but ahead of
the slowly progressing outflow moving across central/south-central
OK. This heating of the moist airmass in place could result in a
corridor of moderate to strong buoyancy, despite relatively warm
temperatures aloft and poor lapse rates. This buoyancy coupled with
moderate deep-layer vertical shear provided by the moderate
northwesterly flow aloft could result in a few strong and organized
updrafts. Given current trends, a reintensification of cells along
the outflow appears to be the most likely convective evolution, with
the resulting linear mode favoring damaging gusts as the primary
risk. That being said, given continued low-level moisture
convergence near the warm front, more discrete development ahead of
the outflow is also a possibility. Any more discrete storms could
become supercellular, with a low-probability risk for a tornado
and/or hail, particularly near the surface boundary.

Additional development is possible this afternoon along the western
edge of the outflow across southwest OK and the TX Big Country/Low
Rolling Plains. A few stronger storms capable of damaging gusts are
possible in these areas.

...Central High Plains...
Low-level upslope flow is expected to contribute to scattered
thunderstorm development the as boundary layer heats across the
central High Plains later this afternoon. Moderate mid-level flow
atop low-level easterlies will result in around 35-40 kt of
effective bulk shear, which is strong enough to support organized
storm structures. This activity will spread southeastward towards
the lower terrain over time, with an attendant risk for isolated
severe hail and gusty winds.

$$

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ACUS01 KWNS 290047
SWODY1
SPC AC 290046

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 PM CDT Thu Aug 28 2025

Valid 290100Z - 291200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL HIGH PLAINS AND FROM NORTH-CENTRAL TEXAS INTO NORTHERN
LOUISIANA...

...SUMMARY...
Thunderstorms capable of a marginal severe threat will be possible
early this evening across parts of eastern Colorado and from
north-central Texas into northern Louisiana.

...Eastern Colorado...
At mid-levels, the latest water vapor imagery shows a ridge over the
central Rockies with a large plume of moisture extending from the
Desert Southwest into the central High Plains. At the surface, high
pressure, associated with a large post-frontal airmass, is located
over much of the central and eastern U.S. Along the western edge of
the airmass, an upslope flow regime is present over the central High
Plains. Relatively isolated thunderstorms are ongoing in eastern
Colorado near an axis of instability, where the RAP has MLCAPE in
the 1000 to 1500 J/kg range. In addition, regional WSR-88D VWPs near
the instability axis have 0-6 km shear around 40 knots. This suggest
the environment could support a marginal severe threat early this
evening. Hail and isolated severe gusts would be the primary
threats.

...North-central/Northeast Texas/Northern Louisiana...
Northwesterly mid-level flow is evident on water vapor imagery from
the Great Plains into the Southeast. A mid-level shortwave trough
appears to be moving through the Lower Mississippi Valley. Scattered thunderstorms are ongoing just ahead of the shortwave over northern
Louisiana, extending westward along a front into northeast and
north-central Texas. To the south of the front, surface dewpoints in
the 70s F are contributing to moderate instability, with the RAP
analyzing MLCAPE in the 1500 to 3000 J/kg range. Near the front, the
00Z soundings at Fort Worth and Shreveport have 0-6 km shear around
30 knots with steep low-level lapse rates. This could be enough for
isolated severe gusts early this evening. Hail will also be
possible.

..Broyles.. 08/29/2025

$$

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ACUS01 KWNS 290458
SWODY1
SPC AC 290457

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1157 PM CDT Thu Aug 28 2025

Valid 291200Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN AND CENTRAL HIGH PLAINS...AND IN PARTS OF THE SABINE
RIVER VALLEY...

...SUMMARY...
Thunderstorms with potential for hail and isolated severe gusts will
be possible today across parts of the southern and central High
Plains. A few marginally severe gusts could also occur over parts of
the Sabine River Valley.

...Southern and Central High Plains...
At mid-levels, flow will be northwesterly over much of the central
U.S. today, as a ridge remains in place over the central High
Plains. At the surface, a low is forecast to move eastward through
southwestern South Dakota as a lee trough deepens across western
Nebraska and eastern Colorado. As surface temperatures warm and
low-level convergence increases, scattered thunderstorms are
expected to develop near the surface trough. Along and to the east
of the trough, surface dewpoints in the lower to mid 60s F will
contribute to an axis of moderate instability by afternoon. In
addition, RAP forecast soundings along this corridor show moderate
deep-layer shear, owing mostly to speed shear in the mid-levels.
This instability/shear environment could be enough for a marginal
severe threat late this afternoon and early this evening, with the
primary threats being for hail and isolated severe gusts.

...Sabine River Valley...
A mid-level trough will move across the eastern U.S. today, as
cyclonically curved northwesterly flow remains over much of the
Southeast. At the surface, a slow-moving front will be positioned
from east Texas eastward into the central Gulf Coast states.
Thunderstorms are expected to be ongoing near the front in the
morning. This convection should move southeastward across the lower
Mississippi Valley during the day. To the southwest of this
convection, the airmass will remain undisturbed from southeast Texas
into southwest Louisiana. This will allow for stronger surface
heating, which should result in a pocket of moderate instability by
afternoon. Isolated thunderstorms that develop within this pocket of instability could produce marginally severe wind gusts, mainly when
low-level lapse rates become steep in the mid to late afternoon.

..Broyles/Thornton.. 08/29/2025

$$

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ACUS01 KWNS 291254
SWODY1
SPC AC 291252

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 AM CDT Fri Aug 29 2025

Valid 291300Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL/SOUTHERN HIGH PLAINS AND SABINE RIVER VALLEY...

...SUMMARY...
Thunderstorms capable of large hail and isolated severe wind gusts
will be possible mainly late this afternoon into evening across
parts of the southern and central High Plains. A few marginally
severe storms could also occur today over parts of the Sabine River
Valley.

...Central/southern High Plains...
Multiple ridge-riding mid/upper-level disturbances will transition
generally east/eventually southeastward from the central Rockies and
northern High Plains today. Weak lee-side low development will occur
across southeast Colorado and also perhaps farther north across the
central High Plains, with modestly sharpening low-level convergence
in vicinity of the lee trough. This will lead to a gradual
enhancement of low-level upslope flow particularly across east-central/southeast Colorado and northeast New Mexico.

Storms should develop/increase by mid-afternoon and gradually move
eastward off the Colorado mountains/Raton Mesa vicinity, with other
development occurring near the surface boundary extending
north-northeastward into west-central Nebraska/southern South
Dakota. Surface dewpoints in the lower to mid 60s F will contribute
to an axis of moderate instability by peak heating. With moderately
strong northwesterly mid-level flow persisting regionally, 35-40 kt
or greater effective shear will exist from the Raton Mesa vicinity
across the central High Plains into west-central Nebraska. A few
supercells capable of large hail may occur, with the additional
possibility of wind damage, especially with a probable clustering of
storms across eastern Colorado/northeast New Mexico toward western
Kansas and the Oklahoma/Texas Panhandles.

...Sabine River Valley...
A relatively widespread corridor of showers/thunderstorms are
ongoing this morning across northeast Texas to central/southeast
Louisiana to the north of a front that will settle southward today
across the region. A related cloud canopy will extend southward into
the warm sector, but moderate destabilization should occur into the
afternoon south of the front and on the south/southwest flank of the
residual early day storms. Some stronger storms could persist and/or
develop near the front this afternoon, with isolated instances of
damaging winds a possibility as low-level lapse rates steepen.

..Guyer/Bentley.. 08/29/2025

$$

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ACUS01 KWNS 291628
SWODY1
SPC AC 291626

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1126 AM CDT Fri Aug 29 2025

Valid 291630Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS
WESTERN/CENTRAL NEBRASKA...

...SUMMARY...
Thunderstorms capable of large hail and isolated severe wind gusts
will be possible mainly late this afternoon into evening across
parts of the southern and central High Plains. A few marginally
severe storms could also occur today over parts of the Sabine River
Valley.

...Central/Southern High Plains...
Recent surface analysis show a reservoir of low-level moisture
across the central/southern High Plains, varying from the mid 60s
across eastern NM into the lower 60s across northeast CO and the NE
Panhandle. General expectation is for modest upslope flow to
contribute to another day of afternoon/evening thunderstorms across
much of central/eastern CO and eastern NM. Thunderstorms also look
probable farther north in the vicinity of a weak surface low, which
is expected to develop along a sharpening lee trough over the NE
Panhandle. Current surface low over western SD will likely fill
throughout the day, although there could still be enough low-level
convergence near the remnant troughing to support a few
thunderstorms as well. In general, there looks to be more overall
storm coverage than the last few days.

Some modest enhancement of the mid-level flow is possible as the
low-amplitude shortwave trough currently over southern UT continues northeastward through the periphery of the ridge into the central
Rockies. The strongest flow will extend from northern CO/southeast
WY into central NE, where elongated hodographs result in a wind
profile that supports supercells capable of large hail. Lapse rates
are generally poor, but ample low-level moisture should still result
in enough buoyancy for mature updrafts. Highest storm coverage
across this region is anticipated over western NE, where 15% hail
probabilities were introduced.

A secondary area of greater storm coverage is expected farther south
from southeast CO through northeast NM as storms move eastward off
the Colorado mountains/Raton Mesa vicinity. Mid-level westerly flow
will be a bit weaker here than farther north but should still be
sufficient for around 35-40 kt of effective bulk shear. Lapse rates
are poor and overall storm strength will likely be limited by
tempered buoyancy. Even so, multicells and a supercell or two are
still possible initially, with eventual clustering as storms move
across eastern Colorado/northeast New Mexico toward western Kansas
and the Oklahoma/Texas Panhandles. Isolated hail is possible with
the initially more cellular storms, with a trend towards damaging
gusts as storms become more linear.

...Sabine River Valley...
A relatively widespread corridor of showers/thunderstorms is
ongoing this morning from east Texas into central/southeast
Louisiana, to the north of a front that will continue to settle
southward today. A related cloud canopy extends across the warm
sector, but moderate destabilization should still occur into the
afternoon south of the front and on the south/southwest flank of the
residual early day storms. Some stronger storms could persist and/or
develop this afternoon, with isolated instances of damaging winds a
possibility as low-level lapse rates steepen.

..Mosier/Lyons.. 08/29/2025

$$

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ACUS01 KWNS 291959
SWODY1
SPC AC 291958

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Fri Aug 29 2025

Valid 292000Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF
WESTERN/CENTRAL NEBRASKA...SOUTHEAST COLORADO AND ADJACENT AREAS...

...SUMMARY...
Thunderstorms capable of large hail and isolated severe wind gusts
will be possible mainly late this afternoon into evening across
parts of the southern and central High Plains.

...20Z Update...
Given observational and CAM guidance trends, an area of greater
supercell potential appears evident in parts of southeast Colorado
and nearby vicinity. Discrete storms would be most likely within the
surface trough. A cluster or two of storms could also potentially
move off the higher terrain later this afternoon. Large hail and
isolated severe winds would be the primary threats, though a brief
tornado could occur in the surface trough.

Observational trends also suggest limited potential for severe
storms in the Sabine Valley region. Severe probabilities have been
removed.

..Wendt.. 08/29/2025

.PREV DISCUSSION... /ISSUED 1126 AM CDT Fri Aug 29 2025/

...Central/Southern High Plains...
Recent surface analysis show a reservoir of low-level moisture
across the central/southern High Plains, varying from the mid 60s
across eastern NM into the lower 60s across northeast CO and the NE
Panhandle. General expectation is for modest upslope flow to
contribute to another day of afternoon/evening thunderstorms across
much of central/eastern CO and eastern NM. Thunderstorms also look
probable farther north in the vicinity of a weak surface low, which
is expected to develop along a sharpening lee trough over the NE
Panhandle. Current surface low over western SD will likely fill
throughout the day, although there could still be enough low-level
convergence near the remnant troughing to support a few
thunderstorms as well. In general, there looks to be more overall
storm coverage than the last few days.

Some modest enhancement of the mid-level flow is possible as the
low-amplitude shortwave trough currently over southern UT continues northeastward through the periphery of the ridge into the central
Rockies. The strongest flow will extend from northern CO/southeast
WY into central NE, where elongated hodographs result in a wind
profile that supports supercells capable of large hail. Lapse rates
are generally poor, but ample low-level moisture should still result
in enough buoyancy for mature updrafts. Highest storm coverage
across this region is anticipated over western NE, where 15% hail
probabilities were introduced.

A secondary area of greater storm coverage is expected farther south
from southeast CO through northeast NM as storms move eastward off
the Colorado mountains/Raton Mesa vicinity. Mid-level westerly flow
will be a bit weaker here than farther north but should still be
sufficient for around 35-40 kt of effective bulk shear. Lapse rates
are poor and overall storm strength will likely be limited by
tempered buoyancy. Even so, multicells and a supercell or two are
still possible initially, with eventual clustering as storms move
across eastern Colorado/northeast New Mexico toward western Kansas
and the Oklahoma/Texas Panhandles. Isolated hail is possible with
the initially more cellular storms, with a trend towards damaging
gusts as storms become more linear.

...Sabine River Valley...
A relatively widespread corridor of showers/thunderstorms is
ongoing this morning from east Texas into central/southeast
Louisiana, to the north of a front that will continue to settle
southward today. A related cloud canopy extends across the warm
sector, but moderate destabilization should still occur into the
afternoon south of the front and on the south/southwest flank of the
residual early day storms. Some stronger storms could persist and/or
develop this afternoon, with isolated instances of damaging winds a
possibility as low-level lapse rates steepen.

$$

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ACUS01 KWNS 300039
SWODY1
SPC AC 300038

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 PM CDT Fri Aug 29 2025

Valid 300100Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN AND CENTRAL HIGH PLAINS...

...SUMMARY...
Thunderstorms with potential for hail and isolated severe gusts will
be possible from early to mid evening across parts of the southern
and central High Plains.

...Southern and Central High Plains...
On water vapor imagery, northwesterly mid-level flow is evident over
much of the central U.S. with a ridge over the central High Plains.
At the surface, a moist airmass is located across the southern and
central Plains, where dewpoints are mostly in the 60s F. An axis of
moderate instability is analyzed along the western edge of the moist
airmass from far eastern New Mexico north-northeastward into
west-central Nebraska. Scattered strong thunderstorms are ongoing
near the instability axis, with a few that are severe. The wind
profile on the WSR-88D VWP at Dodge City appears to be
representative along the instability axis, with 0-6 km shear near 45
knots and strong mid-level speed shear. This will continue to
support a marginal severe threat from early to mid evening, mainly
with the storms that are close to the instability axis. Hail and
isolated severe gusts will be the primary threats. The severe threat
will gradually diminish as instability decreases over the next few
hours.

..Broyles.. 08/30/2025

$$

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ACUS01 KWNS 300552
SWODY1
SPC AC 300551

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1251 AM CDT Sat Aug 30 2025

Valid 301200Z - 311200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
A few strong thunderstorms will be possible across parts of the
southern and central Plains today, but any severe potential should
remain low.

...DISCUSSION...
Flow at mid-levels will remain northwesterly over the top of a moist
airmass today in the southern and central Plains. A weak upslope
flow regime will be in place to the east of a surface trough over
eastern New Mexico and the Texas Panhandle. As surface temperatures
warm during the day across this airmass, scattered thunderstorms
will develop. Isolated storms may form near the surface trough and
instability axis, with increased convective coverage further to the
east in the less unstable air. A few strong storms will be possible
in areas where convection is co-located with maximized instability.
However, lapse rates will be weak suggesting that the severe
potential will remain low in the southern and central Plains today.
Elsewhere across the continental U.S., no severe threat is expected
today and tonight.

..Broyles/Thornton.. 08/30/2025

$$

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ACUS01 KWNS 301250
SWODY1
SPC AC 301248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Sat Aug 30 2025

Valid 301300Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN HIGH PLAINS...

...SUMMARY...
Some strong to locally severe thunderstorms may occur late this
afternoon and evening across the southern High Plains.

...Southern High Plains...
A belt of moderate-strength west-northwesterly flow aloft will
persist atop a moist airmass regionally. Post-MCS air mass
influences and lingering cloud cover/outflows may be factors into
the afternoon, but RAP/HRRR-related guidance has trended a bit more
unstable and potentially more conducive to some isolated severe
storms later today. While confidence in forecast details are not
particularly high, this potential appears to be mainly focused in a
corridor across northeast New Mexico into the Texas Panhandle/Texas
South Plains, and possibly western Oklahoma later this afternoon
into evening. This is where locally moderate destabilization may
occur coincident with effective shear magnitudes that may reach
30-40 kt, with storm development focused near the surface trough
and/or influenced by differential heating. A few instances of severe
hail and/or wind will be possible.

..Guyer/Bentley.. 08/30/2025

$$

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