• DAY48SVR: Nws Storm Prediction Center Norman Ok

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Mon Feb 23 08:38:45 2026
    ACUS48 KWNS 230838
    SWOD48
    SPC AC 230837

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0237 AM CST Mon Feb 23 2026

    Valid 261200Z - 031200Z

    ...DISCUSSION...
    The upper-air pattern across the US will remain characterized as
    broad, fast, northwest flow for most of the forecast period.
    Embedded within this flow, a series of shortwave troughs will move
    across the US. The first, and potentially most impactful of these
    troughs will move across the eastern US on Thursday and Friday (Days
    4 and 5).

    A surface low will develop across portions of the Tennessee Valley
    early in the day Thursday in response to increasing large-scale
    ascent associated with the aforementioned shortwave trough. This low
    will quickly move east then northeast, pushing a cold front through
    much of the Southeast US. A couple days of moisture return will
    result in surface dewpoints in the 50Fs to perhaps low 60Fs ahead of
    this cold front. Despite poor lapse rates and meager buoyancy
    profiles, strong convergence along the front should yield a narrow
    band of forced ascent/convection. A strong low-level jet and curved
    low-level hodographs indicated in forecast soundings may support a
    few isolated damaging wind gusts or perhaps a brief tornado or two
    with this convection, even absent widespread lightning. Although
    confidence is increasing that a band of strongly forced convection
    will occur along the cold front, confidence remains too low in where
    damaging wind gusts/brief tornado may occur to introduce
    unconditional 15% severe probabilities.

    In the wake of this cold front, the severe potential looks to be
    rather limited as surface moisture is suppressed south into the
    northern Gulf until next weekend at the earliest, when southerly
    return flow should develop across Texas and Oklahoma.

    ..Marsh.. 02/23/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Feb 24 09:47:53 2026
    ACUS48 KWNS 240947
    SWOD48
    SPC AC 240946

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0346 AM CST Tue Feb 24 2026

    Valid 271200Z - 041200Z

    ...DISCUSSION...
    The severe potential will remain low through this forecast period as
    the atmosphere undergoes a pattern change.

    Ensemble guidance is in good agreement that in the wake of a
    departing trough, a frontal boundary will stall across the northern
    Gulf Coast on Friday (Day 4), largely confining appreciable
    low-level moisture to the Gulf. The front remains loosely in place
    until late this weekend (Sunday -- Day 6) when it washes out and
    redevelops farther north. This occurs coincident with a transition
    of the upper-air pattern from a single belt of broadly northwest
    flow to a split flow regime (ridge over trough).

    By early next week (Days 7 and 8) an expansive upper-level ridge
    will take shape across much of the US while a closed low develops
    and then opens up beneath this ridge across the Southwest. The
    position and evolution of the closed low should place modest
    southwest flow across much of the Plains by the end of the forecast
    period. Southerly winds to the east of the resulting High Plains lee
    trough should support a gradual moistening of the Plains' low-level environment.

    Although ensemble guidance is in relatively good agreement about the large-scale pattern evolution, considerable differences exist with
    the finer details, such as quality and northward extent of the
    moisture return, timing of specific feature evolution, and resulting
    placement of any precipitation potential -- including thunderstorms.
    In any event, the overall resulting pattern and pattern recognition
    favors an increase in thunderstorm and perhaps severe potential
    across the central US just beyond this forecast period.

    ..Marsh.. 02/24/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Feb 25 09:54:30 2026
    ACUS48 KWNS 250954
    SWOD48
    SPC AC 250953

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0353 AM CST Wed Feb 25 2026

    Valid 281200Z - 051200Z

    ...DISCUSSION...
    Ensemble guidance continues to support a large-scale change to the
    overall upper-air pattern during this forecast period. The western ridge/eastern trough should flip, evolving toward a western trough
    and eastern ridge. As this happens, southwest mid-level flow into
    the central US will support a gradual warming/moistening of the
    Plains' low-level environment. Details of how far north and the
    overall quality of the moisture return remain to be seen.

    This moisture return will begin in earnest on Saturday (Day 4) as
    southerly winds take hold across the central US. However, a cold
    front will suppress this low-level moisture south into central Texas
    on Sunday and Monday (Days 5 and 6), with some guidance members
    suggesting a reinforcing frontal push on Tuesday.

    By the middle of next week (Days 7 and 8), the frontal boundary
    should weaken across Texas and redevelop northward. This will allow
    low-level moisture to begin advancing northward into the Central
    Plains. However the speed and strength of this low-level moisture
    advection varies greatly between different ensembles and even within
    the membership of specific ensembles. As such, the overall potential
    for organized severe weather on any day looks to be too low for
    unconditional probabilities. However, pattern recognition suggests
    thunderstorm (and severe) potential should increase across portions
    of the central US just beyond this forecast period.

    ..Marsh.. 02/25/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Feb 25 10:41:01 2026
    ACUS48 KWNS 251040
    SWOD48
    SPC AC 251039

    Day 4-8 Convective Outlook RESENT 1
    NWS Storm Prediction Center Norman OK
    0439 AM CST Wed Feb 25 2026

    Valid 281200Z - 051200Z

    ...DISCUSSION...
    Ensemble guidance continues to support a large-scale change to the
    overall upper-air pattern during this forecast period. The western ridge/eastern trough should flip, evolving toward a western trough
    and eastern ridge. As this happens, southwest mid-level flow into
    the central US will support a gradual warming/moistening of the
    Plains' low-level environment. Details of how far north and the
    overall quality of the moisture return remain to be seen.

    This moisture return will begin in earnest on Saturday (Day 4) as
    southerly winds take hold across the central US. However, a cold
    front will suppress this low-level moisture south into central Texas
    on Sunday and Monday (Days 5 and 6), with some guidance members
    suggesting a reinforcing frontal push on Tuesday.

    By the middle of next week (Days 7 and 8), the frontal boundary
    should weaken across Texas and redevelop northward. This will allow
    low-level moisture to begin advancing northward into the Central
    Plains. However the speed and strength of this low-level moisture
    advection varies greatly between different ensembles and even within
    the membership of specific ensembles. As such, the overall potential
    for organized severe weather on any day looks to be too low for
    unconditional probabilities. However, pattern recognition suggests
    thunderstorm (and severe) potential should increase across portions
    of the central US just beyond this forecast period.

    ..Marsh.. 02/25/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thu Feb 26 09:58:06 2026
    ACUS48 KWNS 260958
    SWOD48
    SPC AC 260956

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0356 AM CST Thu Feb 26 2026

    Valid 011200Z - 061200Z

    ...DISCUSSION...
    Early in the forecast period a transition across the western US will
    take place as the low-amplitude ridge over the Great Basin/Southwest
    shifts eastward, giving way to an amplifying trough over the West.
    Several speed maxima are forecast to traverse the flow while it
    remains primarily northwesterly over the central US early in the
    period. At the surface, uncertainty remains regarding the southern
    extent of the arctic front pushing into the Plains on Day 3.
    Uncertainties in the position of this front will cause low
    confidence in the projected quality of the low-level moisture
    recovery across the southern Plains through Tuesday. As the
    upper-air pattern across the central US transitions from
    northwesterly to southwesterly, and return flow commenses, the
    shallow nature of the modified arctic airmass may initially limit
    the northward penetration of the richest theta-e air.

    As the period progresses into Wednesday and Thursday, ensemble
    guidance remains in general agreement regarding the transition to an
    amplified western trough and central-to-eastern ridge. However, the
    timing and phasing of individual shortwaves moving into the Plains
    remains a source of forecast uncertainty.

    The first meaningful shortwave is forecast to eject into the Plains
    early Wednesday, inducing surface cyclogenesis that should support a
    northward advancement of the warm sector. Any severe risk with this
    trough on Wednesday (Day 7) will be predicated on the evolution of
    the moisture return on prior days.

    On Thursday, a second, more potent trough is forecast to approach
    the Plains. Current ensemble guidance shows quite a bit more
    variance with the timing, amplitude, and evolution of this second
    trough. Some guidance brings this wave out as single, potent trough,
    with other guidance suggesting a series of more subtle shortwave
    troughs ejecting into the Plains from Thursday into Saturday. These discrepancies will have an impact on the location, timing, and
    magnitude of any potential severe weather threat.

    Despite these timing differences, the synoptic setup (increasing
    low-level moisture, strengthening southwest flow aloft, repeated
    cyclogenesis) is favorable for organized severe weather over the
    Plains and lower Mississippi Valley. While the severe weather threat
    should increase by Wednesday and Thursday (Days 7 and 8), the
    specific orientation of frontal boundaries and the northward extent
    of the moisture return will be highly dependent on the evolution of
    the upper-lows. Given that models tend to struggle with handling the
    details of pattern changes, will hold off on trying to highlight any
    specific corridor for severe probabilities for Wednesday and
    Thursday at this time.

    ..Marsh.. 02/26/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Fri Feb 27 10:01:12 2026
    ACUS48 KWNS 271001
    SWOD48
    SPC AC 270959

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0359 AM CST Fri Feb 27 2026

    Valid 021200Z - 071200Z

    ...DISCUSSION...
    ...Monday/Day 4 to Tuesday/Day 5...
    At mid-levels, a trough is forecast to move across California on
    Monday as zonal flow remains in place over the central and eastern
    U.S. On Tuesday, the trough is forecast to move eastward across the
    Desert Southwest, as flow becomes southwesterly in the south-central
    states. A moist airmass will likely be in place on Monday and
    Tuesday from eastern parts of the southern Plains into the lower to
    mid Mississippi Valley. Thunderstorm development will be possible
    each afternoon and evening across parts of the moist airmass. In
    areas that destabilize the most, a marginal severe threat may
    develop.

    ...Wednesday/Day 6 to Friday/Day 8...
    On Wednesday, the trough is forecast to move into the southern and
    central High Plains, as an associated mid-level jet ejects
    northeastward across the southern High Plains. At the surface, a
    cold front is forecast to move into the southern Plains, as a moist
    airmass spreads northward from north Texas into southern and eastern
    Oklahoma. As surface temperatures warm during the day, thunderstorms
    appear most likely to form along the cold front, and further south
    across parts of the warm sector. Moderate deep-layer shear is
    evident on model forecasts which should support a severe threat
    during the afternoon and evening, with a potential for large hail
    and severe wind gusts. While confidence is high enough to add a
    severe threat area across the southern Plains, variance does exist
    concerning the timing of the shortwave trough. If the trough moves
    across the southern Plains faster, then the area could need to be
    adjusted.

    On Thursday, the mid-level trough is forecast to eject northeastward
    into the Great Lakes region, as a large upper-level trough digs into
    the Desert Southwest. Southwesterly mid-level flow will likely be in
    place over parts of the Great Plains, with a moist and unstable
    airmass remaining over much of Texas and Oklahoma. As surface
    temperatures warm, isolated strong to severe storms will be possible
    in areas that destabilize the most. At this time, there is
    uncertainty regarding the magnitude of the threat because some
    solutions move a shortwave ridge northeastward across the
    south-central U.S.

    On Friday, model forecasts suggest that a large-scale upper-level
    trough will move through the western U.S. Ahead of this feature,
    thunderstorms will continue to be possible over parts of the
    southern and central Plains, where a moist and unstable airmass is
    forecast to be in place. However, a significant amount of variance
    exists among the model solutions, suggesting that uncertainty is
    substantial concerning the magnitude and spacing of any severe
    threat.

    ..Broyles.. 02/27/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Feb 28 09:54:18 2026
    ACUS48 KWNS 280954
    SWOD48
    SPC AC 280952

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0352 AM CST Sat Feb 28 2026

    Valid 031200Z - 081200Z

    ...DISCUSSION...
    ...Tuesday/Day 4 and Wednesday/Day 5...
    On Tuesday, a mid-level trough will move eastward across the Desert
    Southwest, as southwesterly flow remains in place over the southern
    Plains. As the trough approaches Tuesday night, scattered elevated thunderstorms will be possible from the Red River northeastward into
    the mid Mississippi Valley. From Tuesday night into Wednesday, a
    moist airmass will spread northward from east-central Texas into the
    Arklatex and Ozarks. Thunderstorm development will be possible near
    the boundary from central Oklahoma into southern Missouri during the
    day on Wednesday, and further southeast across the warm sector in
    the afternoon and evening. Model forecasts continue to show moderate instability ahead of the front. In addition, a mid-level jet streak
    is forecast to pass through the southern Plains during the
    afternoon, creating deep-layer shear sufficient for severe storms.
    Supercells with wind damage and isolated large hail will be
    possible. Model solutions are in better agreement this run,
    suggesting the severe threat will be a bit further east than was
    previously forecast. For this reason, the severe threat area has
    been adjusted eastward towards the Ark-La-Tex.

    ...Thursday/Day 6 to Saturday/Day 8...
    On Thursday, the shortwave trough is forecast to move through the
    mid Mississippi Valley, as the cold front advances southeastward
    into the Ark-La-Tex and mid Mississippi Valley. Thunderstorms will
    be possible near the front during the day into the evening.
    Deep-layer shear and instability are forecast to be somewhat
    limited, which should keep any severe threat marginal.

    From Thursday night into Friday, southwesterly mid-level flow is
    forecast to strengthen over the south-central states. In response,
    moisture advection will likely continue over the southern Plains as
    moderate instability re-develops across much of the southern Plains.
    Scattered thunderstorms should form over parts of this airmass
    Thursday night from west-central Texas north-northeastward into
    parts of the central Plains. The potential for storm development
    should continue into Friday along the northern edge of the moist
    airmass from north-central Texas northeastward into the Ozarks.
    Although a severe threat could develop over parts of the southern
    Plains and Ozarks Friday afternoon and evening, there is
    considerable uncertainty, mainly due to variance among model
    solutions.

    On Saturday, am amplified upper-level trough is forecast to develop
    over the western U.S., as mid-level flow becomes south-southwesterly
    from the Gulf Coast States into the mid Mississippi Valley. A moist
    airmass is forecast over much of the Gulf Coast states, where
    scattered thunderstorms will be possible during the day. Although a
    severe threat could develop during the day, uncertainty is high
    concerning the placement of a more concentrated severe threat area.

    ..Broyles.. 02/28/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Mar 1 10:01:25 2026
    ACUS48 KWNS 011001
    SWOD48
    SPC AC 010959

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0359 AM CST Sun Mar 01 2026

    Valid 041200Z - 091200Z

    ...DISCUSSION...
    ...Wednesday/Day 4 to Thursday/Day 5...
    On Wednesday, model forecasts continue to move a mid-level shortwave
    trough across the southern Plains. A cold front is forecast to
    advance southeastward into Oklahoma as a moist and unstable airmass
    resides southward from the front over much of the southern Plains.
    Surface dewpoints across southeast Oklahoma and north-central to
    northeast Texas should be in the lower to mid 60s F, and moderate
    instability will be possible by afternoon. Thunderstorm development
    appears likely across parts of this unstable airmass from the mid
    afternoon into the evening. Moderate deep-layer shear should support
    a severe threat, with a potential for large hail and damaging wind
    gusts associated with supercells.

    On Thursday, the shortwave trough is forecast to move into the mid
    Mississippi Valley, as a much larger upper-level trough moves
    through the Desert Southwest. A moist and unstable airmass should
    remain in place over the southern Plains. However, large-scale
    ascent should be weak between these two systems, which should dampen
    the severe potential across most of the south-central U.S. The most
    likely location for an isolated to marginal severe threat would be
    in the Ark-La-Tex Thursday afternoon.

    ...Friday/Day 6 to Sunday/Day 8...
    At mid-levels, southwest flow is forecast across much of the central
    U.S. on Friday, as a large trough remains over the southwestern
    states. Moisture advection is expected to continue over the Great
    Plains and Upper Midwest along a corridor of strong low-level flow.
    Model forecasts are in general agreement that moderate instability
    will develop over much of this airmass by Friday afternoon, and that
    scattered thunderstorms will form. Convective development will be
    supported by the right entrance region of a mid-level jet ejecting northeastward through the central Plains. This mid-level jet will be
    associated with moderate to strong deep-layer shear, supporting
    scattered severe storms potentially across a large part of the moist
    sector. The current thinking is that the severe threat will be
    maximized during the late afternoon and evening from central Texas northeastward into the lower Missouri Valley. Large hail and
    damaging wind gusts are expected to the primary threats, but a few
    tornadoes remain possible.

    On Saturday, the upper-level system in the central U.S. is forecast
    to move into the Great Lakes region, as a cold front advances
    quickly southeastward into the western Gulf Coast states, and lower
    Mississippi Valley. An isolated severe threat could develop ahead of
    the front Saturday afternoon, but confidence is low concerning the
    spatial distribution of any threat. On Sunday, isolated to scattered thunderstorms will again be possible in the Gulf Coast region.
    However, deep-layer shear is forecast to be weak over much of this
    area, suggesting any severe potential should remain marginal.

    ..Broyles.. 03/01/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Mon Mar 2 09:59:31 2026
    ACUS48 KWNS 020959
    SWOD48
    SPC AC 020958

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0358 AM CST Mon Mar 02 2026

    Valid 051200Z - 101200Z

    ...DISCUSSION...
    ...Thursday/Day 4 and Friday/Day 5...
    At mid-levels, a shortwave trough is forecast to move through the
    mid Mississippi Valley on Thursday as flow remains southwesterly
    across the south-central U.S. An upper-level system will be located
    in the Desert Southwest. At the surface, moisture advection is
    forecast across the southern Plains, where surface dewpoints will be
    mostly in the 50s and 60s F by afternoon. As surface temperatures
    warm during the day, an axis of moderate instability is forecast to
    develop to the east of a dryline from west-central Texas
    north-northeastward into the eastern Texas Panhandle and western
    Oklahoma. Along this axis of instability, moderate deep-layer is
    forecast, along with steep mid-level lapse rates. This will likely
    support a severe threat during the afternoon and evening. Supercells
    with large hail, damaging wind gusts and a tornado threat will be
    possible.

    On Friday, mid-level southwesterly flow will strengthen across parts
    of the southern and central Plains, as a mid-level jet ejects
    northeastward into the central U.S. At the surface, a moist airmass
    with moderate instability is forecast to be in place by afternoon
    from north-central Texas north-northeastward into the lower Missouri
    Valley. Model forecasts are in agreement that scattered
    thunderstorms will develop across this unstable airmass during the
    afternoon and evening. Moderate deep-layer shear and steep mid-level
    lapse rates should be favorable for supercells with large hail. Wind
    damage and tornadoes will also be possible with supercells and
    bowing line segments. Some solutions suggest that the threat will
    persist into the overnight period as a low-level jet ramps up across
    the region.

    ...Saturday/Day 6 to Monday/Day 8...
    Mid-level southwesterly flow is expected to continue over the
    south-central U.S. on Saturday, as a cold front moves southward
    across the southern Plains and Ozarks. To the south of the front,
    the models forecast pockets of moderate instability, and suggest
    that scattered to numerous thunderstorms will develop. In addition,
    moderate to strong deep-layer shear is forecast across the northern
    edge of the moist sector. Model consensus suggests that a severe
    threat will develop Saturday afternoon and evening, mainly from
    west-central Texas northeastward into the western Ozarks.

    The cold front is forecast to continue moving southward into the
    western Gulf Coast states on Sunday. Scattered thunderstorms are
    forecast to develop near and to the south of the front Sunday
    afternoon, where an isolated severe threat will be possible.
    Confidence is low concerning the spatial distribution of any
    potential threat. On Monday, a shortwave ridge is forecast to move
    over the top of a moist airmass in the southern Plains. This
    scenario could support an isolated severe threat in the afternoon.
    However, uncertainty is high at this range in the forecast period.

    ..Broyles.. 03/02/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Mar 3 09:54:06 2026
    ACUS48 KWNS 030954
    SWOD48
    SPC AC 030952

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0352 AM CST Tue Mar 03 2026

    Valid 061200Z - 111200Z

    ...DISCUSSION...
    ...Friday/Day 4 and Saturday/Day 5...
    A strong upper-level system is forecast to eject northeastward into
    the central High Plains on Friday, as an associated 60 to 80 knot
    mid-level jet translates northeastward ahead of the trough. At the
    surface, a moist and unstable airmass will likely be in place from
    central and east Texas northward into the lower Missouri Valley.
    Warming surface temperatures and increasing low-level convergence
    will support scattered convective initiation to the west of the
    moist axis. Storms are expected to grow upscale in the mid to late
    afternoon, moving eastward toward an axis of strong low-level flow.
    Moderate instability, strong deep-layer shear and steep lapse rates
    will be favorable for supercells. Supercells should be capable of
    producing tornadoes, large hail and severe wind gusts. The greatest
    potential is forecast from near the Red River in north Texas north-northeastward across eastern Oklahoma into eastern Kansas and northwestern Missouri, where a 30 percent contour has been added. A
    severe threat is also forecast northeastward into parts of the mid
    to upper Mississippi Valley, where strong deep-layer shear and
    sufficient low-level moisture will be in place for a severe threat.

    On Saturday, the upper-level system is forecast to move through the north-central U.S., as a cold front advances southeastward into the
    Ark-La-Tex, mid Mississippi Valley, and lower Great Lakes. Scattered
    to numerous thunderstorms are expected to develop ahead of the front
    during the day as surface temperatures warm. It appears that a
    marginal severe threat will develop during the mid to late afternoon
    over much of the northwestern edge of the moist sector from the
    Ark-La-Tex northeastward into the Ohio Valley.

    ...Sunday/Day 6 to Tuesday/Day 8...
    On Sunday in the mid-levels, a 90 to 110 knot jet is forecast to
    move into the northern U.S., as westerly flow remains over much of
    the east-central U.S. A front is forecast to become quasi-stationary
    from the Ozarks eastward into the southern Appalachians. Isolated to
    scattered thunderstorms with a marginal severe threat may develop to
    the south of the front during the afternoon.

    On Monday and Tuesday, moisture advection is forecast to take place
    from the central Plains into the Great Lakes, as mid-level flow
    again becomes southwesterly. Moisture and instability should be
    favorable for isolated severe storms Monday afternoon in areas that
    heat up sufficiently. On Tuesday, models forecast a strong
    upper-level system to eject northeastward into the south-central
    U.S. If this scenario works out, a greater severe threat appears
    possible Tuesday afternoon and evening over the southern and central
    Plains. However, uncertainty is considerable at this range in the
    forecast period due to a relatively wide spread in the model
    guidance.

    ..Broyles.. 03/03/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Mar 4 09:58:47 2026
    ACUS48 KWNS 040958
    SWOD48
    SPC AC 040956

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0356 AM CST Wed Mar 04 2026

    Valid 071200Z - 121200Z

    ...DISCUSSION...
    ...Saturday/Day 4 and Sunday/Day 5...
    On Saturday at mid-levels, a shortwave trough is forecast to move
    eastward across the north-central U.S., as flow remains
    southwesterly from the southern Plains to the Eastern Seaboard. A
    cold front is forecast to move southeastward across the southern
    Plains, Ozarks, mid Mississippi Valley and Ohio Valley. Surface
    dewpoints ahead of the front are forecast to be mostly in the 60s F
    with pockets of moderate instability developing in the afternoon.
    Scattered to numerous thunderstorms are expected to develop and move southeastward into the moist airmass. Although an isolated severe
    threat will be likely in some areas, uncertainty is considerable
    concerning the area with the greatest severe threat. The current
    thinking is that the severe threat will be concentrated in two
    areas, with one being from south-central Texas northeastward into
    northern Louisiana, and a second being located in the Ohio Valley. A
    15 percent area may need to be added in either of these two areas in
    later outlooks.

    On Sunday, a moist and unstable airmass is forecast along the
    western Gulf Coast. Isolated storms associated with a marginal
    severe threat could develop in the afternoon. Large-scale ascent
    will be limited which should keep any severe potential localized.

    ...Monday/Day 6 to Wednesday/Day 8...
    West-southwesterly mid-level flow is forecast to continue on Monday
    across much of the central and eastern U.S. Low-level moisture
    return is forecast to take place over the southern and central
    Plains, where the models suggest moderate instability will be
    possible by afternoon. As a low-level jet strengthens during the
    afternoon and evening, isolated to scattered thunderstorms should
    develop in areas that heat up sufficiently. A severe threat would be
    possible. However, spatial uncertainty exists concerning where any
    severe threat will be the greatest.

    On Tuesday, model forecasts are in general agreement, moving an
    upper-level trough northeastward into the southern High Plains. An
    associated mid-level jet is forecast to eject northeastward ahead of
    the system. Model forecasts suggest that the airmass ahead of the
    trough will become moderately unstable by Tuesday afternoon. This
    combined with strong large-scale ascent should support scattered
    severe storms in the afternoon and evening. The favored severe
    threat area is expected from parts of the southern and central
    Plains eastward into the Ozarks.

    On Wednesday, the upper-level trough is forecast to move across the south-central U.S., as a cold front advances eastward into the
    Southeast. A severe threat may again develop Wednesday afternoon as
    the airmass ahead of the front becomes unstable. However, there is
    considerable model spread concerning the timing of features at this
    extended range.

    ..Broyles.. 03/04/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thu Mar 5 09:38:51 2026
    ACUS48 KWNS 050938
    SWOD48
    SPC AC 050936

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0336 AM CST Thu Mar 05 2026

    Valid 081200Z - 131200Z

    ...DISCUSSION...
    ...Sunday/Day 4 and Monday/Day 5...
    A moist airmass in the Gulf Coast region on Sunday will advect
    northward into the east-central U.S. on Monday. Over the top of this
    airmass, west-southwesterly mid-level flow will be in place.
    Although large-scale ascent is forecast to be limited on both days,
    isolated strong to marginally severe thunderstorms will be possible
    in the afternoon in areas that heat up sufficiently. The greatest
    potential for severe storms appears to be on Monday afternoon in the Ark-La-Tex, where moisture and low-level flow are currently forecast
    to be maximized.

    ...Tuesday/Day 6 to Thursday/Day 8...
    On Tuesday, model forecasts move an upper-level system across
    northern Mexico, and retain southwesterly mid-level flow over much
    of the south-central U.S. A moist and unstable airmass is forecast
    over much of the southern and central Plains eastward into the lower
    to mid Mississippi Valley. It appears that large-scale ascent
    associated with the upper-level trough will gradually increase over
    the southern and central Plains on Tuesday. In response, scattered thunderstorms should develop over parts of the moist sector Tuesday
    afternoon and evening. Although model forecasts have slowed the
    progression of the upper-level low, a belt of strong mid-level flow
    is still forecast over the south-central U.S. on Tuesday. This
    suggests that deep-layer shear will support severe thunderstorm
    development, potentially across a broad area. The severe threat is
    expected to continue from evening into the overnight period as the
    upper-level trough approaches.

    On Wednesday, the upper-level trough and an associated cold front is
    forecast to move into the western Gulf Coast states. Ahead of the
    system, a moist and unstable airmass appears likely by afternoon.
    Thunderstorms that develop near and ahead of the front could have a
    severe threat. However, there are still questions about the timing
    of the trough and front. If model runs continue to suggest that the
    system will move into the western Gulf Coast states on Wednesday,
    then a risk area may need to be added. An isolated risk may also
    develop on Wednesday northeastward ahead of the front in parts of
    the Tennessee and Ohio Valleys.

    On Thursday, the upper-level trough is forecast to move into the
    eastern U.S., as the cold front moves offshore into the western
    Atlantic. Thunderstorms with an isolated severe threat would be
    possible along parts of the Eastern Seaboard before the front
    passes. However, uncertainty at this extended range is considerable.

    ..Broyles.. 03/05/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Fri Mar 6 09:40:28 2026
    ACUS48 KWNS 060940
    SWOD48
    SPC AC 060938

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0338 AM CST Fri Mar 06 2026

    Valid 091200Z - 141200Z

    ...DISCUSSION...
    ...Day 4/Monday...

    A weak upper shortwave impulse is expected to migrate across the
    Ozarks/Lower MS Valley on Monday. This will support a narrow
    corridor of enhanced westerly flow aloft atop a moistening boundary
    layer. Isolated thunderstorms may develop across the ArkLaTex to
    Lower MS Valley vicinity within the warm advection regime, and few
    storms could become strong to locally severe. However, modest
    forcing and otherwise lack of low-level focus precludes a 15 percent delineation.

    ...Day 5/Tuesday into Day 6/Wednesday...

    An upper low and attendant shortwave trough over northwest Mexico is
    forecast to eject eastward toward the southern High Plains on
    Tuesday. At the same time, a broad upper trough within northern
    stream flow will develop east from the northern Plains to the Upper
    Midwest. As this occurs, a belt of enhanced southwesterly flow aloft
    will overspread a large warm/moist sector from the southern Plains
    to the Mid/Lower MS and Ohio Valleys. A complex surface pattern is
    expected to emerge, influenced by the split-flow upper troughing
    pattern. A baroclinic zone extending from OK the Mid-MS Valley area
    will be one focus for severe thunderstorm potential. Meanwhile, lee
    surface troughing across west TX and a developing dryline will be
    another focus for severe storm development. While details remain
    uncertain, these surface features, combined with strengthening
    southwesterly flow overspreading a warm and unstable airmass, will
    likely foster a broad area of severe thunderstorm potential from the
    southern Plains into the Midwest.

    As the upper troughs from Day 5/Tuesday continue east across the
    southern Plains and Great Lakes on Day 6/Wednesday, a cold front is
    expected to develop southeast across the Ohio Valley into east
    Texas. Spread among forecast guidance increases during this time,
    leading to more uncertainty. However, most guidance has some overlap
    of favorable low-level moisture and instability with stronger
    mid/upper level flow across portions of east TX into the Lower MS
    valley. As a result, a 15 percent area has been delineated. This
    area my need to shift/expand northeast with time depending on trends
    in model guidance, but currently, it is uncertain if sufficient
    destabilization will occur further northeast, precluding severe
    probabilities into the TN/OH Valleys vicinity.

    ...Days 7-8/Thursday-Friday...

    Predictability is low toward the end of the forecast period as
    forecast model spread continues to increase. While it is plausible
    some severe risk could persist into the Southeast on Day 7/Thursday
    as the upper trough over the Lower MS Valley continues to migrate
    east, uncertainty is too high to include probabilities at this time.

    ..Leitman.. 03/06/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Fri Mar 6 10:48:01 2026
    ACUS48 KWNS 061047
    SWOD48
    SPC AC 061046

    Day 4-8 Convective Outlook CORR 1
    NWS Storm Prediction Center Norman OK
    0446 AM CST Fri Mar 06 2026

    Valid 091200Z - 141200Z

    CORRECTED FOR TEXT

    ...DISCUSSION...
    ...Day 4/Monday...

    A weak upper shortwave impulse is expected to migrate across the
    Ozarks/Lower MS Valley on Monday. This will support a narrow
    corridor of enhanced westerly flow aloft atop a moistening boundary
    layer. Isolated thunderstorms may develop across the ArkLaTex to
    Lower MS Valley vicinity within the warm advection regime, and a few
    storms could become strong to locally severe. However, modest
    forcing and otherwise lack of low-level focus precludes a 15 percent delineation.

    ...Day 5/Tuesday into Day 6/Wednesday...

    An upper low and attendant shortwave trough over northwest Mexico is
    forecast to eject eastward toward the southern High Plains on
    Tuesday. At the same time, a broad upper trough within northern
    stream flow will develop east from the northern Plains to the Upper
    Midwest. As this occurs, a belt of enhanced southwesterly flow aloft
    will overspread a large warm/moist sector from the southern Plains
    to the Mid/Lower MS and Ohio Valleys. A complex surface pattern is
    expected to emerge, influenced by the split-flow upper troughing
    pattern. A baroclinic zone extending from OK to the Mid-MS Valley
    area will be one focus for severe thunderstorm potential. Meanwhile,
    lee surface troughing across west TX and a developing dryline will
    be another focus for severe storm development. While details remain
    uncertain, these surface features, combined with strengthening
    southwesterly flow overspreading a warm and unstable airmass, will
    likely foster a broad area of severe thunderstorm potential from the
    southern Plains into the Midwest.

    As the upper troughs from Day 5/Tuesday continue east across the
    southern Plains and Great Lakes on Day 6/Wednesday, a cold front is
    expected to develop southeast across the Ohio Valley into east
    Texas. Spread among forecast guidance increases during this time,
    leading to more uncertainty. However, most guidance has some overlap
    of favorable low-level moisture and instability with stronger
    mid/upper level flow across portions of east TX into the Lower MS
    Valley. As a result, a 15 percent area has been delineated. This
    area may need to shift/expand northeast with time depending on
    trends in model guidance, but currently, it is uncertain if
    sufficient destabilization will occur further northeast, precluding
    severe probabilities into the TN/OH Valleys vicinity.

    ...Days 7-8/Thursday-Friday...

    Predictability is low toward the end of the forecast period as
    forecast model spread continues to increase. While it is plausible
    some severe risk could persist into the Southeast on Day 7/Thursday
    as the upper trough over the Lower MS Valley continues to migrate
    east, uncertainty is too high to include probabilities at this time.

    ..Leitman.. 03/06/2026

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Mar 7 08:36:40 2026
    ACUS48 KWNS 070836
    SWOD48
    SPC AC 070834

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0234 AM CST Sat Mar 07 2026

    Valid 101200Z - 151200Z

    ...DISCUSSION...
    ...Days 4-5/Tue-Wed...

    An active pattern with severe thunderstorm potential is expected
    Tuesday and Wednesday from the southern Plains to the Mid/Lower MS
    and OH Valleys. Medium range guidance is in fairly good agreement
    during this time. Starting on Tuesday, an upper low over northern
    Mexico will shift east/northeast, becoming an open wave as it begins
    to merge with a northern stream upper trough developing southeast
    across the northern/central Plains through early Wednesday. A belt
    of strong southwesterly deep-layer flow will overspread a large warm
    sector on Tuesday. Lee cyclogenesis is forecast across the
    central/southern High Plains, along with a second surface low
    developing over IA as the northern stream upper trough approaches.
    This setup will allow for a sharpening dryline/Pacific front across
    the southern Plains, while a cold front develops southeast into the
    MO/Mid-MS Valley overnight. Strong ascent should focus thunderstorm
    development across the warm sector ahead of these surface boundaries
    within a strongly sheared environment, and potentially widespread
    severe thunderstorm activity is possible.

    The large-scale upper trough and attendant surface cold front will
    continue to progress eastward on Wednesday. Uncertainty does
    increase, especially with north and east extent of severe potential.
    How far east convection develops on Tuesday and how much downstream destabilization occurs is somewhat unclear. Nevertheless, a
    deepening surface cyclone is forecast to develop northeast from the
    Great Lakes into Ontario and Quebec, while strong deep layer
    southwesterly flow overspreads a moist warm sector ahead of the
    surface front. This should set the stage for at least isolated to
    scattered severe thunderstorm potential along the length of the cold
    front through Wednesday evening.

    Given uncertainties mentioned above, these areas are likely to be
    adjusted in coming days as details become better resolved, but the
    overall pattern should support a couple of active severe weather
    days over a broad area.

    ...Day 6/Thu...

    Uncertainty increases by Thursday as spread among medium range
    guidance increases quite a bit with respect to the evolution/timing
    of the upper trough. Some severe potential could persist/develop
    across the Mid-Atlantic region, but predictability is too low to
    include a 15 percent delineation at this time.

    Beyond Thursday, severe thunderstorm potential will likely be low as
    the upper pattern become lower amplitude and stronger westerly flow
    remains confined to the northern tier of the U.S., along with Gulf
    moisture largely remaining offshore behind the cold frontal passage.

    ..Leitman.. 03/07/2026

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sun Mar 8 09:16:48 2026
    ACUS48 KWNS 080916
    SWOD48
    SPC AC 080914

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0414 AM CDT Sun Mar 08 2026

    Valid 111200Z - 161200Z

    ...DISCUSSION...
    ...Day 4/Wed...

    A large-scale upper trough will continue to shift east across the
    central U.S. on Wednesday, becoming oriented from the Upper Great
    Lakes to the central Gulf coast vicinity by Thursday morning. An
    embedded shortwave within the base of this trough will move from the
    southern Plains to the Deep South, while the northern branch of the
    trough moves across the Midwest. Strong deep-layer southwesterly
    flow will overspread a broad warm sector across much of the Midwest
    and southern U.S. Meanwhile, a cold front will develop southeast
    through the period, tracking across much of the Mid/Lower MS, OH and
    TN Valleys.

    Uncertainty exists regarding where convection may be ongoing
    Wednesday morning, and some potential exists for widespread
    thunderstorm activity across parts of the Midwest. As a result, it
    is uncertain how far north quality thermodynamics will exist.
    Nevertheless, it appears likely at least some severe risk will exist
    across the Ohio Valley given favorable boundary-layer moisture and
    impressive vertical shear profiles. Further southwest toward the
    Lower MS Valley into the Deep South vicinity, morning convection may
    be more limited compared to further north, allowing for more
    extensive destabilization ahead of the surging cold front. A
    mixed-mode of supercells ahead of the cold front, and an organized
    line of storms along the cold front will be possible across this
    area.

    As mesoscale details become better resolved in the coming days, the
    severe area for Wednesday is likely to shift some. However, the
    overall pattern suggests a broad area of severe thunderstorm
    potential is probable on Wednesday.

    ...Day 5/Thu...

    Some severe thunderstorm potential could persist into portions of
    the Mid-Atlantic and Southeast. However, uncertainty is fairly high
    given this potential will depend on evolution of convection on Day
    4/Wed, which could be quite extensive and outpace the surface front
    Wednesday night into early Day 5/Thu. As such, predictability is
    low.

    ...Days 6-8/Fri-Sun...

    Severe thunderstorm potential appears low during the weekend as
    broad upper troughing persists across the central/eastern U.S.

    ..Leitman.. 03/08/2026

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Mon Mar 9 08:33:26 2026
    ACUS48 KWNS 090833
    SWOD48
    SPC AC 090831

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0331 AM CDT Mon Mar 09 2026

    Valid 121200Z - 171200Z

    ...DISCUSSION...
    ...Day 4/Thu...

    Some low-end severe thunderstorm risk could persist into Day 4/Thu
    across portions of the Southeast as an upper trough pivots toward
    the Atlantic coast in tandem with an eastward-advancing surface cold
    front. Ahead of the front, a moist airmass will be in place from
    GA/FL northeast toward southeast VA. Convection will likely be
    ongoing Thursday morning, and persistent warm advection will result
    in widespread cloudiness. This will limit destabilization and lapse
    rates are expected to remain modest. Overall, severe potential
    appears less than 15 percent.

    ...Days 5-8/Fri-Mon...

    Severe thunderstorm potential appears low Friday and Saturday as a
    prior cold frontal passage into the Gulf leaves a dearth of boundary
    layer moisture in its wake. Another upper trough is expected to
    deepen over the Plains and the eastern U.S. late in the period. Some
    moisture return may occur ahead of this feature before another cold
    front develops southeast across the eastern half of the CONUS. This
    could bring some increasing thunderstorm potential to parts of the south-central or southeast U.S., however, at this time any better
    moisture return looks displaced to the south of stronger flow aloft.

    ..Leitman.. 03/09/2026

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tue Mar 10 07:49:01 2026
    ACUS48 KWNS 100748
    SWOD48
    SPC AC 100747

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0247 AM CDT Tue Mar 10 2026

    Valid 131200Z - 181200Z

    ...DISCUSSION...
    Severe thunderstorm potential will remain low on Days 4-5/Fri-Sat as
    a cold frontal passage and surface high pressure over the central
    U.S. leave a dry/stable airmass across much of the CONUS east of the
    Rockies.

    On Saturday, lower-amplitude, quasi-zonal flow over much of the U.S.
    will amplify as a shortwave upper trough deepens over the Rockies
    and emerges over the High Plains by Day 6/Sunday morning. As this
    occurs, modest Gulf moisture will return northward across east TX
    into the Mid-South. A strong surface low is forecast to move across
    the Upper Midwest on Sunday as the upper trough continues to dig and
    shift east into the Midwest. This will bring a cold front southeast
    across portions of the Plains and Midwest. Some severe potential
    could develop across central portions of the U.S. on Day 6/Sunday as
    the cold front sweeps eastward, but confidence is low given a lack
    of deeper moisture return overlapping with stronger shear across the
    Midwest.

    As the upper trough and surface cold front continue east on Day
    7/Monday, some low-end severe potential could possibly develop
    across the Mid-Atlantic to the Southeast, but confidence is low
    given similar concerns to those on Day 6/Sunday. With this system
    moving offshore by the end of the period, severe potential appears
    low on Day 8/Tuesday.

    ..Leitman.. 03/10/2026

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wed Mar 11 07:54:41 2026
    ACUS48 KWNS 110754
    SWOD48
    SPC AC 110752

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0252 AM CDT Wed Mar 11 2026

    Valid 141200Z - 191200Z

    ...DISCUSSION...
    ...Days 4-6/Sat-Mon...

    An upper trough will begin to deepen as it moves over the northern
    Rockies and into the northern/central High Plains on
    Saturday/Saturday night. As this occurs, a lee cyclone will deepen
    as it shifts east across the central Plains toward the MO Valley by
    early Sunday. Modified Gulf moisture will return northward in
    response to increasing southerly low-level flow ahead of the surface
    cyclone and attendant cold front. Medium range guidance is in fairly
    good agreement that any deeper/higher quality moisture will remain
    confined to east TX and the immediate Gulf coast on Sunday. With
    northward extent into the Mid-South, Mid-MS and Lower OH, and TN
    Valleys, 50s F dewpoints appear more likely. The upper trough will
    intensify and shift east across the Midwest and south-central U.S.
    on Sunday, but stronger flow aloft will remain displaced from better
    quality moisture return. While some severe potential could develop
    from east TX into the Lower OH/TN Valleys as a strong cold front
    tracks east across the central U.S. on Sunday, probabilities appear
    less than 15 percent at this time.

    This system will shift east across the eastern U.S. on Monday,
    though any severe potential along the East Coast appears low at this
    time as the primary forcing for ascent lags behind the surface
    front.

    ...Days 7-8/Tue-Wed...

    An amplified upper ridge will build across the western U.S. during
    the end of Tuesday and Wednesday while upper troughing persists
    across the East. Surface high pressure and the prior cold frontal
    passage into the Gulf will leave a stable and dry airmass in place,
    precluding severe potential.

    ..Leitman.. 03/11/2026

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thu Mar 12 08:17:17 2026
    ACUS48 KWNS 120817
    SWOD48
    SPC AC 120815

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0315 AM CDT Thu Mar 12 2026

    Valid 151200Z - 201200Z

    ...DISCUSSION...
    ...Day 4/Sunday - ArkLaTex/Lower MS Valley into the Middle MS/Lower
    OH Valleys...

    An intense upper trough will deepen over the Plains and shift east
    to the MS Valley on Sunday. From late afternoon into the nighttime
    hours, an 80-100 kt jet streak will develop within the base of the
    trough and overspread portions of the region. At the surface, an
    already strong cyclone will deepen further as it moves from the
    Lower MO Valley to the Lower Great Lakes vicinity. As this occurs, a
    strong cold front will sweep eastward across the southern Plains and
    much of the Midwest and Southern U.S., becoming oriented from Ohio
    to the FL Panhandle by Monday morning.

    While strengthening southerly low-level flow will develop ahead of
    the front, stronger Gulf moisture return will be confined to TX and
    the Lower MS Valley vicinity, with mainly 50s dewpoints expected
    with northward extent across the Middle MS and OH Valley regions.
    Furthermore, capping is expected ahead of the cold front,
    potentially limiting warm sector convection. Nevertheless, modest
    moisture and steepening midlevel lapse rates will support at least
    weak destabilization very near the cold front. A narrow line of
    strongly-forced convection is expected to develop along the cold
    front and move across portions of OK/TX into the Middle/Lower MS and
    Lower OH/TN Valley regions. Given intense deep-layer flow near and
    just behind the cold front, strong/damaging wind potential will
    exist within a modest instability/high shear environment. A 15
    percent severe delineation has been included from the ArkLaTex into
    the Mid-South/Lower MS Valley vicinity. Depending on low-level moisture/instability trends, this area may need to be expanded north
    and east into a larger portion of the Middle MS/Lower OH/TN Valley
    vicinity in subsequent outlooks.

    ...Day 5/Monday - Southeast to Mid-Atlantic...

    Severe thunderstorm potential will likely continue into Monday as
    the intense upper trough continues to migrate east from the MS
    Valley toward the Eastern Seaboard. Intense deep-layer southwesterly
    flow will overspread portions of the Southeast to the Mid-Atlantic.
    Meanwhile, 60s F dewpoints will extend from southeast GA northward
    through the Mid-Atlantic ahead of a sharp cold front. Pre-frontal
    surface troughing across the VA/NC Piedmont also will support
    backing low-level winds, leading to enhanced low-level shear.
    Depending on how much cloud cover and warm advection precipitation
    occurs ahead of the cold front, stronger destabilization may be
    inhibited. Nevertheless, at least weak instability is forecast ahead
    of a strongly forced line of convection along the eastward-advancing
    cold front. This activity alone could produce a swath of strong to
    severe wind gusts. A more conditional risk of supercells across the
    warm sector exists across eastern VA/NC, but this is more uncertain.
    Given damaging wind potential with the strongly forced linear
    convection, a 15 percent severe delineation has been added for
    portions of the region.

    ...Days 6-8/Tuesday-Thursday...

    Severe thunderstorm potential will be low Tuesday through Thursday
    as strong surface high pressure builds in the wake of the earlier
    cold frontal passage. A dry/stable airmass will prevail as Gulf
    moisture remains well offshore.

    ..Leitman.. 03/12/2026

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Fri Mar 13 09:00:23 2026
    ACUS48 KWNS 130900
    SWOD48
    SPC AC 130858

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0358 AM CDT Fri Mar 13 2026

    Valid 161200Z - 211200Z

    ...DISCUSSION...
    Significant severe winds and the potential for a few tornadoes will
    develop on Monday over parts of the Carolinas and Mid Atlantic.

    Models are in good agreement with the large scale pattern on
    Monday/D4, depicting a deep upper trough moving out of the
    Mississippi Valley and ejecting in negative-tilt fashion across the
    Mid Atlantic and into to the Northeast.

    Given the antecedent upper ridging on the previous day, low-level
    southerly winds will help to moisten the air mass well ahead of an
    approaching cold front. By 12Z Monday, 60s F dewpoints will already
    extend from northern GA across the Piedmont and into southeast VA,
    and this plume of moisture will rapidly spread north with near 60 F
    dewpoints into southeast PA by 00Z.

    There appears to be two regimes for severe potential on Monday.
    First, up to 1000 J/kg MUCAPE may develop well ahead of the
    approaching cold front, and there is some indication that scattered
    convection may occur across the warm sector from mid to late
    afternoon. If this occurs, supercells would be most likely, with
    potential for a few tornadoes from the Carolinas into eastern VA.

    Models also indicate an elongated pressure fall/rise couplet, which
    when combined with 50-70 kt 850 mb winds and extreme low-level
    shear, could easily result in a QLCS along the cold front with
    corridors of significant damaging winds and embedded tornado risk.

    Beyond Monday/D4, stable air behind this system will likely preclude
    any severe threat through Friday/D8.

    ..Jewell.. 03/13/2026

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Fri Mar 13 19:53:27 2026
    ACUS48 KWNS 131953
    SWOD48
    SPC AC 131951

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0251 PM CDT Fri Mar 13 2026

    Valid 161200Z - 211200Z

    ...DISCUSSION...
    Significant severe winds and the potential for a few tornadoes will
    develop on Monday over parts of the Carolinas and Mid Atlantic.

    Models are in good agreement with the large scale pattern on
    Monday/D4, depicting a deep upper trough moving out of the
    Mississippi Valley and ejecting in negative-tilt fashion across the
    Mid Atlantic and into to the Northeast.

    Given the antecedent upper ridging on the previous day, low-level
    southerly winds will help to moisten the air mass well ahead of an
    approaching cold front. By 12Z Monday, 60s F dewpoints will already
    extend from northern GA across the Piedmont and into southeast VA,
    and this plume of moisture will rapidly spread north with near 60 F
    dewpoints into southeast PA by 00Z.

    There appears to be two regimes for severe potential on Monday.
    First, up to 1000 J/kg MUCAPE may develop well ahead of the
    approaching cold front, and there is some indication that scattered
    convection may occur across the warm sector from mid to late
    afternoon. If this occurs, supercells would be most likely, with
    potential for a few tornadoes from the Carolinas into eastern VA.

    Models also indicate an elongated pressure fall/rise couplet, which
    when combined with 50-70 kt 850 mb winds and extreme low-level
    shear, could easily result in a QLCS along the cold front with
    corridors of significant damaging winds and embedded tornado risk.

    Beyond Monday/D4, stable air behind this system will likely preclude
    any severe threat through Friday/D8.

    ..Jewell.. 03/13/2026

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Fri Mar 13 20:06:26 2026
    ACUS48 KWNS 132006
    SWOD48
    SPC AC 132004

    Day 4-8 Convective Outlook AMEND 1
    NWS Storm Prediction Center Norman OK
    0304 PM CDT Fri Mar 13 2026

    Valid 161200Z - 211200Z

    AMENDED TO EXPAND D4/MONDAY THREAT AREAS

    ...DISCUSSION...
    ...Updated discussion for D4...
    The majority of deterministic and ensemble model guidance agree on a
    deep midlevel trough and associated cold front that will move
    eastward across the Appalachians and to the Atlantic coast by
    Tuesday morning. Severe storms could be ongoing at the beginning of
    the period along the northeast Gulf coast into GA. The warm sector, characterized by boundary-layer dewpoints in the 60s, will expand
    northward (generally east of the Appalachians) through the day as
    far north as PA. Though clouds could limit downstream surface
    heating somewhat, very strong wind profiles and focused forcing for
    ascent will favor a continuation of convection along the front, as
    well as pre-frontal convection, with the potential to produce
    relatively widespread damaging winds and several tornadoes.

    ...Previous discussion below...
    Significant severe winds and the potential for a few tornadoes will
    develop on Monday over parts of the Carolinas and Mid Atlantic.

    Models are in good agreement with the large scale pattern on
    Monday/D4, depicting a deep upper trough moving out of the
    Mississippi Valley and ejecting in negative-tilt fashion across the
    Mid Atlantic and into to the Northeast.

    Given the antecedent upper ridging on the previous day, low-level
    southerly winds will help to moisten the air mass well ahead of an
    approaching cold front. By 12Z Monday, 60s F dewpoints will already
    extend from northern GA across the Piedmont and into southeast VA,
    and this plume of moisture will rapidly spread north with near 60 F
    dewpoints into southeast PA by 00Z.

    There appears to be two regimes for severe potential on Monday.
    First, up to 1000 J/kg MUCAPE may develop well ahead of the
    approaching cold front, and there is some indication that scattered
    convection may occur across the warm sector from mid to late
    afternoon. If this occurs, supercells would be most likely, with
    potential for a few tornadoes from the Carolinas into eastern VA.

    Models also indicate an elongated pressure fall/rise couplet, which
    when combined with 50-70 kt 850 mb winds and extreme low-level
    shear, could easily result in a QLCS along the cold front with
    corridors of significant damaging winds and embedded tornado risk.

    Beyond Monday/D4, stable air behind this system will likely preclude
    any severe threat through Friday/D8.

    ..Thompson.. 03/13/2026

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sat Mar 14 08:52:01 2026
    ACUS48 KWNS 140851
    SWOD48
    SPC AC 140850

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0350 AM CDT Sat Mar 14 2026

    Valid 171200Z - 221200Z

    ...DISCUSSION...
    On Tuesday/D4, a large upper trough will move across the Northeast,
    though the associated surface cold front will already be well
    offshore the East Coast with high pressure over land. Behind this
    upper trough, models indicate a large upper ridge will be situated
    over the Southwest for several days, with a northwest flow pattern
    across the Plains. Given this pattern, minimal appreciable moisture
    return is expected over the CONUS, and severe storms appear unlikely
    through Saturday/D8.

    ..Jewell.. 03/14/2026

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