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  • DAY2SVR: Nws Storm Prediction Center Norman Ok

    From COD Weather Processor @1:2320/107 to All on Wed Sep 2 05:54:24 2026
    ACUS02 KWNS 020554
    SWODY2
    SPC AC 020552

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1252 AM CDT Wed Sep 02 2026

    Valid 031200Z - 041200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    THE UPPER MIDWEST AND PARTS OF THE EASTERN OHIO VALLEY TO THE
    MID-ATLANTIC...

    ...SUMMARY...
    Severe storms, accompanied by severe wind and hail (including a
    couple 2 inch diameter stones and 75+ mph gusts), are possible
    across portions of the Upper Midwest. At least scattered
    severe-wind-producing storms are also possible from the eastern Ohio
    Valley to the Mid-Atlantic coastline.

    ...Synopsis...
    An upper ridge will remain centered over the MS Valley as upper
    troughs persist across the Northeast and Interior West tomorrow
    (Thursday). Multiple impulses, accompanied by cooler temperatures
    and stronger flow aloft, will pivot around the eastern periphery of
    the upper ridge and overspread a moist boundary layer over the Upper
    Midwest and OH Valley/Mid-Atlantic regions. Ample buoyancy and
    vertical wind shear over both areas will support at least scattered thunderstorms, several of which may be severe.

    ...Portions of the Upper MS Valley...
    Guidance consensus depicts a subtle impulse cresting the upper ridge
    over the northern Plains and impinging on the Upper MS Valley by
    afternoon peak heating, serving as the most likely impetus for
    convective initiation. Storms will most likely develop somewhere
    along the SD/MN border to central MN, preceded by a surface warm
    front draped from southern MN, to southern WI and eastern IA.
    Surface dewpoints will exceed 70 F along this front, with 8+ C/km
    mid-level lapse rates overspreading this moisture, yielding
    3000-4000 J/kg MLCAPE. Coincident with this strong buoyancy will be
    50 kts of effective bulk shear, with forecast soundings showing
    elongated hodographs.

    The current thinking is that initial storms will be supercellular,
    accompanied by mainly a severe wind and hail threat (a few stones of
    which may exceed 2 inches in diameter). However, if storms merge, a cold-pool-driven MCS may develop, perhaps even taking on bowing
    tendencies should it traverse the surface boundary. In this
    scenario, a focused severe wind swath could occur, and a couple of
    gusts may exceed 75 mph. Given such subtle forcing for ascent
    expected, and the dependency on finer mesoscale details for a
    higher-end severe threat, only Category 2/Slight Risk probabilities
    were introduced for now. If consistency in guidance consensus
    continues to show bow echo evolution, higher severe probabilities
    may be needed in future outlooks.

    ...Parts of the OH Valley to the Mid-Atlantic Coastline...
    Another in a series of mid-level impulses will traverse the
    Mid-Atlantic region during the day. A diffuse differential heating
    zone should be in place somewhere near the PA/MD border, which will
    likely be the location of convective initiation by late morning or
    early afternoon. There is also the possibility that upstream
    convective complexes, remnant from Day 1 storms along the
    larger-scale warm front, may approach from the OH Valley and track
    toward the Eastern Seaboard though the day. Regardless of the
    convective scenario, storms should overspread 70+ F surface
    dewpoints (which will support over 2000 J/kg MLCAPE). Given modest northwesterly flow aloft, any storms that become sustained will be
    accompanied by a severe gust threat, though an instance of hail
    cannot be ruled out. Higher severe probabilities are not entirely
    out of the question once mesoscale details on convective placement,
    timing, and evolution become clearer.

    ..Squitieri.. 09/02/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Wed Sep 2 17:21:12 2026
    ACUS02 KWNS 021720
    SWODY2
    SPC AC 021718

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1218 PM CDT Wed Sep 02 2026

    Valid 031200Z - 041200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    THE NORTH DAKOTA-MINNESOTA RED RIVER VALLEY INTO THE UPPER
    MIDWEST...AND IN PARTS OF THE UPPER OHIO VALLEY TO MID-ATLANTIC
    COAST...

    ...SUMMARY...
    Severe storms, accompanied by predominantly severe wind gusts and
    hail (including 75+ mph gusts and hailstones greater than two
    inches), are possible from the North Dakota-Minnesota Red River
    Valley into the upper Midwest. At least widely scattered severe
    storms capable of mainly damaging wind gusts are also possible from
    the upper Ohio Valley to the Mid-Atlantic coastline.

    ...Synopsis...

    A high-latitude omega block will persist through the forecast
    period, featuring upper lows along the Pacific Northwest coast and
    over QC, which bracket a mid-level ridge centered along the MS
    Valley. Several smaller-scale perturbations are expected to move
    through the broader-scale flow regime from the northern Plains and
    the upper MS Valley through the Great Lakes into the Mid-Atlantic,
    aiding in thunderstorm development in those areas. At the surface,
    an area of low pressure is forecast to develop through the Dakotas
    into MN, while a preceding warm front lifts north through the upper
    MS Valley and upper Midwest. The boundary is expected to extend
    southeast through the Great Lakes into the Mid-Atlantic, where its
    location may be modified from convective outflow stemming from
    thunderstorms Wednesday night into Thursday morning.


    ...Northern Plains into the upper Great Lakes...

    A plume of steep mid-level lapse rates associated with an
    elevated-mixed layer (EML) will reside atop a moist boundary layer
    in the vicinity of the surface low and warm front, yielding a
    strongly unstable air mass by afternoon with MLCAPE increasing to
    3000-4000+ J/kg. Amidst a backdrop of general height rises, the
    progression of weak disturbances through the building ridge will
    promote periods of forcing for ascent. The first of these may occur
    Thursday morning when elevated thunderstorms appear possible from
    portions of the mid-MO Valley into upper Midwest. Given the presence
    of the EML and sufficient cloud-bearing shear, isolated occurrences
    of large hail may accompany the strongest storms as they spread east
    into the upper Great Lakes.

    In the wake of the early-day storms, residual capping associated
    with the building ridge coupled with the subtle forcing for ascent
    results in considerable model variability in the location of
    subsequent, surface-based storm development Thursday afternoon into
    night. Nonetheless, the degree of instability and up to 40-50 kt of
    deep-layer shear will conditionally support higher-order storm modes
    including supercells and bowing structures, both of which are
    depicted by the suite of various 12Z CAMs. Hail in excess of two
    inches, severe wind gusts greater than 75 mph, and a couple of
    tornadoes appear possible with the most intense storms.

    The 15% hail and accompanying CIG1 contours have been expanded into
    the ND-MN Red River Valley and in parts of WI to account for the
    large hail potential. Otherwise, the forecast will remain largely
    unchanged due to the spatial uncertainty in surface-based storm
    development. Once finer-scale details become more clear, an upgrade
    to a level 3/Enhanced Risk may become necessary, primarily for
    severe winds associated with a cold-pool-driven MCS.


    ...Upper Ohio Valley to the Mid-Atlantic Coast...

    Similar to this morning, clusters of thunderstorms capable of
    isolated occurrences of damaging wind may be ongoing at 12Z Thursday
    over portions of the lower Great Lakes and upper OH Valley regions.
    A subset of the morning storms may intensify by afternoon over the Delmarva/southern Mid-Atlantic with additional storms forming during
    the peak of the diurnal heating cycle in the vicinity of the surface
    front and/or residual outflow boundaries over the upper OH Valley.

    Despite weakening mid-level lapse rates with eastward extent,
    daytime heating combined with dewpoints largely in the low/mid 70s
    will contribute to moderate to strong instability by afternoon along
    and south of the effective surface front with MLCAPE approaching
    2500-3500 J/kg. The frontal zone will coincide with a belt of 40-45
    kt west-northwest mid-level flow, yielding sufficient vertical shear
    for supercells and organized line segments and/or bowing structures.
    The primary hazard will be damaging wind gusts, though isolated
    occurrences of large hail are possible with any supercells that may
    evolve.

    A slight northward shift in the Marginal and Slight Risk
    probabilities has been made to account for stronger instability and
    an associated severe risk evident in various 12z models.

    ..Mead.. 09/02/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Thu Sep 3 05:44:06 2026
    ACUS02 KWNS 030543
    SWODY2
    SPC AC 030542

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1242 AM CDT Thu Sep 03 2026

    Valid 041200Z - 051200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    THE MID ATLANTIC...

    ...SUMMARY...
    Widely scattered severe thunderstorms, mainly producing damaging
    gusts, are expected across portions of the southern Mid-Atlantic on
    Friday. More isolated severe storms capable of severe winds and
    large hail may occur over parts of the Midwest Friday afternoon into
    night.

    ...Synopsis...
    Upper ridging will amplify over the Plains states, with upper
    troughs meandering over the Interior West and along the East Coast.
    East of the ridge crest, multiple impulses will track southeastward
    across the Midwest to the Mid-Atlantic, atop a surface warm frontal
    boundary, serving as the impetus for thunderstorm initiation in
    these areas. Given modestly stronger flow and cooler temperatures
    aloft overspreading this moisture-rich surface boundary, a few
    storms may become severe.

    ...Portions of the Mid-Atlantic...
    At least one or more subtle mid-level impulses will pivot around the
    broader East Coast trough, supporting scattered thunderstorm
    initiation by afternoon. By this time, surface temperatures should
    reach 90 F, amid 70 F dewpoints, yielding around 2000 J/kg MLCAPE
    given 6.5-7 C/km mid-level lapse rates. Deep-layer northwesterly
    flow will be in place, supporting 20-40 kts of effective bulk (speed
    shear), favoring multicells and perhaps a transient supercell, the
    strongest of which may produce damaging gusts or an instance of
    hail.

    ...Portions of the Midwest to Ohio Valley...
    Upper support for convective initiation will be even weaker across
    the Midwest/OH Valley compared to the areas closer to the East
    Coast. Nonetheless, 70s F surface dewpoints beneath 7-8 C/km
    mid-level lapse rates will contribute to 3000+ J/kg MLCAPE along a
    surface warm front, where subtle convergence will reside.
    Thunderstorm coverage should be quite isolated. However, any storms
    that manage to mature may become multicellular or supercellular
    given 30+ kts of effective bulk shear in place. An instance or two
    of severe wind or hail are possible.

    ..Squitieri.. 09/03/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Thu Sep 3 16:57:34 2026
    ACUS02 KWNS 031657
    SWODY2
    SPC AC 031655

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1155 AM CDT Thu Sep 03 2026

    Valid 041200Z - 051200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
    THE UPPER OHIO VALLEY INTO THE SOUTHERN MID-ATLANTIC...

    ...SUMMARY...
    Widely scattered severe thunderstorms, mainly producing damaging
    gusts, are expected across portions of the upper Ohio Valley into
    the southern Mid-Atlantic on Friday. More isolated severe storms
    capable of severe winds and large hail may occur over parts of the
    Midwest Friday afternoon into night.

    ...Synopsis...

    A mid-level ridge over central North America will undergo
    considerable amplification between troughs located over the western
    CONUS and eastern Canada into the Northeast. Subtle disturbances
    embedded within the broader-scale flow regime will focus
    thunderstorm development, one of which will progress from the Great
    Lakes into the Mid-Atlantic on Friday.

    At the surface, a lee cyclone will develop over the northern High
    Plains with an associated surface front stretching from the northern
    Plains through the upper Midwest and Great Lakes to the Mid-Atlantic
    coast. The specific location of that boundary by afternoon may be
    affected by convective outflow associated with thunderstorm activity
    tonight into Friday morning.


    ...Upper Ohio Valley to southern Mid-Atlantic...

    There is good agreement across 12Z model guidance that thunderstorms
    will be ongoing at 12Z Friday over portions of the Great Lakes ahead
    of the mid-level disturbance mentioned above. A subset of those
    storms may linger through the morning over the upper OH Valley with
    an associated risk for damaging wind gusts.

    By afternoon, daytime heating across the downstream air mass over
    the southern Mid-Atlantic will combine with boundary-layer dewpoints
    in the low/mid 70s to yield moderate instability with MLCAPE up to
    2000-2500 J/kg. That destabilization process, in conjunction with
    increased forcing for ascent associated with the approaching
    mid-level disturbance, will support intensification of any lingering
    storms moving into the region from the northwest. Additional storms
    are also possible along the effective surface front and lee trough.
    The presence of 25-35 kt of west-northwest deep-layer shear will be
    sufficient for episodic supercell and bowing structures with the
    predominant hazard being damaging wind gusts into evening.

    A modest areal expansion of the Slight Risk wind probabilities has
    been applied to portions of the upper OH Valley given the scenario
    described above.


    ...Midwest...

    Owing to the proximity of the building mid-level ridge and resultant
    capping for surface-based parcels, convective evolution remains
    highly uncertain. The eastern extension of a steep mid-level lapse
    rate plume will overlie lower/mid 70s dewpoints in the vicinity of
    the surface front, supporting moderate to strong instability by
    afternoon with MLCAPE of 3000-4000+ J/kg. The 12Z
    convection-allowing and parameterized model guidance offers varying
    scenarios with respect to the timing and location of storm
    development from Friday afternoon through night. Deep-layer shear
    will be weaker than previous days; however, the magnitude of
    instability will be supportive of a conditional risk for large hail
    and damaging winds with any surface-based storms that can develop.

    Marginal Risk wind and hail probabilities will be maintained in this
    forecast update due to the uncertainties mentioned above.

    ..Mead.. 09/03/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Fri Sep 4 05:06:26 2026
    ACUS02 KWNS 040506
    SWODY2
    SPC AC 040504

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1204 AM CDT Fri Sep 04 2026

    Valid 051200Z - 061200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
    APPALACHIANS TO COASTAL NORTH CAROLINA...

    ...SUMMARY...
    Severe thunderstorms capable of damaging gusts are possible across
    portions of the central Appalachians and Carolinas on Saturday
    afternoon and evening. Isolated occurrences of large hail and severe
    wind gusts also appear possible over parts of the northern Plains
    and vicinity Saturday afternoon into night.

    ...Ohio Valley to southern Mid-Atlantic/Carolinas...

    An upper shortwave disturbance will migrate through northwesterly
    flow aloft, leading to modest height falls across the region on
    Saturday. As this occurs, midlevel northwesterly flow will
    strengthen, supporting effective shear magnitudes in the 25-35 kt
    range. At the surface, a cold front will develop south across the
    Midwest and Mid-Atlantic after 00z. Ahead of the front, a very warm
    and moist airmass will foster a corridor of moderate to strong
    instability.

    Forecast guidance varies with regards to possible morning
    convection, resulting in some uncertainty in the forecast for
    Saturday. Early convection could be ongoing anywhere from the Lower
    Ohio Valley toward the WV/VA mountains as remnants from Day 1
    thunderstorm activity. Whether this early day activity will
    dissipate or re-intensify as it moves into the moist and
    destabilizing downstream airmass is uncertain. Regardless, the
    overall environment will support afternoon and evening thunderstorm
    activity ahead of the southward-advancing front and along a surface
    trough through the parts of the VA/NC/SD Piedmont. Organized
    clusters will mainly pose a damaging wind risk as convection spreads east/southeast during the afternoon and evening.

    ...Northern/Central Plains vicinity...

    Substantial upper ridging will be centered over the Plains on
    Saturday. However, most guidance depicts one of more shortwave
    disturbances migrating northeast from the central Rockies into the
    NE/SD vicinity. Additionally, convection could be ongoing at the
    start of the period across the Mid-MO Valley. Southeasterly
    low-level flow will result in modest boundary layer moisture along a
    surface trough across the northern/central High Plains, with
    increasing dewpoints further east toward the MO River along a
    surface boundary. Steep midlevel lapse rates will support modest
    instability across the High Plains, with moderate to strong
    instability further east.

    If storms are occurring at the beginning of the period across the MO
    Valley, hail and strong wind gusts will be possible, with some
    intensification possible toward midday/early afternoon within the
    very moist/unstable and favorably sheared environment. Additional
    widely scattered thunderstorms are expected to develop along the
    surface trough over the High Plains during the late
    afternoon/evening. This activity could produce strong outflow wind
    gusts given a deeply mixed boundary layer and modest shear, along
    with isolated large hail.

    ..Leitman.. 09/04/2026

    $$

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Fri Sep 4 17:05:44 2026
    ACUS02 KWNS 041705
    SWODY2
    SPC AC 041703

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1203 PM CDT Fri Sep 04 2026

    Valid 051200Z - 061200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO
    VALLEY AND APPALACHIANS TO THE CAROLINAS...

    ...SUMMARY...
    Severe thunderstorms capable of damaging gusts are possible across
    portions of the central Appalachians and Carolinas on Saturday
    afternoon and evening. Isolated occurrences of large hail and severe
    wind gusts also appear possible over parts of the northern Plains
    and vicinity Saturday afternoon into night.

    ...Eastern Carolinas...
    A mid-level trough across the western Atlantic is forecast to
    retrograde slightly on Saturday with an associated surface front
    expected to move slowly southward from the Mid-Atlantic to the
    Carolinas. South of this cold front, a very moist airmass will be in
    place with strong instability, particularly across the eastern
    Carolinas. Farther west, downslope flow off the mountains may result
    in a more stable environment in the western half of the Carolinas.
    This signal varies within the guidance, and confidence is not high
    enough to lower probabilities across this area, but the greater
    threat should remain farther east where mid to upper 70s dewpoints
    and around 30 knots of shear amid a front and height falls aloft
    should support scattered strong to severe storms capable of mostly
    damaging winds.

    ...Ohio Valley...
    Strong heating across eastern Kentucky and vicinity should provide
    an unstable and uncapped airmass by Saturday afternoon. Mid-level
    flow will be relatively weak across this region (~20 knots) and
    therefore, effective shear and storm organization is expected to be
    weak. However, strong heating and steep lapse rates will support
    some damaging wind threat Saturday afternoon/evening. Some guidance
    shows these storms clustering and traversing the Appalachians and
    continuing into western Virginia and western North Carolina. The
    relatively weak shear, and potential for lesser instability due to
    downslope flow across the eastern Appalachians casts significant
    doubt on this potential.

    ...Central to northern Plains...
    Most guidance shows ongoing thunderstorms within a warm-air
    advection zone across southeast South Dakota Saturday morning.
    Isolated large hail is possible with this activity during the
    morning hours before the low-level jet weakens and backs and these thunderstorms weaken by late morning.

    As the mid-level ridge strengthens during the day Saturday, height
    rises will be present across much of the Plains. Despite this,
    upslope flow will develop across the central High Plains. Within
    this region, forecast soundings show moderate instability but weak
    mid-level flow. This will support some isolated large hail and
    severe wind gusts, but the lack of shear should limit the overall
    severe weather threat.

    A more organized cluster of storms may develop across southwest
    Nebraska, but do not expect storm intensity to warrant higher severe
    weather probabilities.

    After 00Z, the low-level jet is forecast to strengthen across the central/northern Plains. This could result in some isolated storm
    development during the overnight period into the Dakotas. Given the
    strong instability forecast across this region, these storms could
    contain large hail or damaging wind gusts.

    ...North-central Montana...
    A mid-level jet streak on the eastern periphery of a mid-level
    trough across the Northwest will remain across Montana for much of
    the period on Saturday. Weak instability may develop as temperatures
    warm into the 70s across west-central Montana Saturday afternoon.
    Overall, moisture will be lacking (30s F dewpoints) which should
    limit the severe weather threat. However, there is some instability
    within a zone of moderate to strong shear. Therefore, one or two
    fast-moving strong storms may develop within this zone, but the
    overall lack of moisture/instability precludes severe weather
    probabilities at this time.

    ..Bentley.. 09/04/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sat Sep 5 05:14:14 2026
    ACUS02 KWNS 050514
    SWODY2
    SPC AC 050512

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1212 AM CDT Sat Sep 05 2026

    Valid 061200Z - 071200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    SOUTH CAROLINA AND GEORGIA...

    ...SUMMARY...
    Strong wind gusts are likely across the Southeast Sunday afternoon
    and early evening. A more uncertain risk for severe wind and hail is
    expected across parts of Montana into the northern Plains and Middle
    Missouri Valley.

    ...MT into the northern Plains and Mid-MO Valley...

    The upper ridge centered over the Plains on Sunday will begin to
    weaken and shift east as a western upper shortwave trough develops
    eastward toward the northern Rockies. As this occurs, several
    shortwave impulses will migrate through the top of the ridge over
    the northern Plains and Mid-MO Valley. Southwesterly deep-layer flow
    also will increase later in the period across MT and the High Plains
    with the approaching of the upper trough. At the surface, low
    pressure will be in place across eastern MT and the western Dakotas,
    with a surface trough extending southward through the central High
    Plains. Meanwhile, a warm front will be draped across northern ND,
    while a quasi-stationary front extends northwest to southeast across
    South Dakota into the MO-Valley. A moist airmass will reside along
    these boundaries, and areas of moderate to strong instability are
    forecast.

    Most guidance depicts early day convection ongoing across parts of
    MN and eastern SD. While evolution of this convection is uncertain,
    it seems possible that it could persist and/or strengthen as it
    shifts southwest across the Mid-MO Valley through afternoon.
    Additional convection is expected to develop along the surface
    trough over the High Plains, near the surface warm front, surface
    low, and later in the evening across much of Montana with the
    approach of the upper trough. Pockets of damaging winds and hail
    will be possible. If confidence increases in areas of greater storm
    coverage, higher probabilities may be needed in later outlooks.

    ...Southern States...

    A weak low is expected to develop southward across GA as a surface
    front sags southward through the period. Ahead of the front, a very
    moist and unstable airmass will be in place, fostering areas of
    moderate to strong instability. Deep-layer flow will remain light
    and vertical shear weak, limiting organized severe potential.
    However, given strong instability, high PWs, frontal forcing, and
    sufficient storm coverage/clustering, isolated to scattered
    strong/damaging wind gusts are expected.

    ..Leitman.. 09/05/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sat Sep 5 17:33:02 2026
    ACUS02 KWNS 051732
    SWODY2
    SPC AC 051730

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1230 PM CDT Sat Sep 05 2026

    Valid 061200Z - 071200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
    GEORGIA AND THE CAROLINAS...

    ...SUMMARY...
    Damaging wind gusts are likely across portions of the Southeast
    Sunday afternoon and early evening. Additional areas at risk for
    severe wind and hail are across parts of northern Utah northward
    into Montana and east into the northern Plains and Middle Missouri
    Valley.

    ... Synopsis ...

    A high-amplitude mid-level ridge will persist across the central US
    on Sunday, with troughing across both the east and west coasts.
    Embedded within the basal region of the western trough, a closed low
    should open up and take on a negative tilt as it moves along the
    northwest periphery of the central ridge.

    At the surface, an anticyclone will be located across the upper
    Great Lakes, ushering in a cooler, drier air mass from the Upper
    Midwest east across the Ohio Valley into the Northeast. Demarcating
    the boundary between this continental air mass and the more maritime
    air mass to the south and west will be a front stretched from the Minnesota-North/South Dakota border south and east to southeast
    Missouri and then east from there to the East Coast.


    ... Southeast ...

    A very humid air mass will be in place across the region, with HREF
    mean dewpoint temperatures in the upper-60Fs to low-70Fs. Diurnal
    heating will allow afternoon temperatures to warm into the
    low-to-mid-90Fs, yielding MUCAPE values in excess of 1500 J/kg. (High-resolution guidance is generally in the 1500-2500 J/kg range,
    with coarser-scale guidance, such as the RAP, showing perhaps as
    high as 4000 J/kg.)

    Scattered thunderstorms will develop during the afternoon as
    convective temperatures are reached. Precipitable water values
    around 2 inches and DCAPE values in excess of 1000 J/kg will support
    heavy, water-laden downbursts capable of scattered wind damage.
    Slightly better deep-layer shear across portions of Georgia and the
    Carolinas may support at least transient thunderstorm organization
    in the form of multi-cell clusters which may pose a slightly greater
    risk of organized wind damage.


    ... Mid-Missouri Valley and Northern Plains ...

    Thunderstorms may be ongoing at the start of the forecast period
    across portions of the area or develop shortly thereafter. These
    thunderstorms will likely be driven by strong warm-air advection
    near the apex of the mid-level ridge. These storms may initially
    pose a risk of large hail and gusty winds. With time, diurnal
    heating may support a transition from elevated-to-surface based
    thunderstorms, increasing the potential for damaging winds,
    especially as low-level lapse rate steepen. Deep-layer shear will
    support individual storms moving southeast while the larger-scale
    evolution will be toward the southwest.

    The exact evolution of this convection, in particular where the
    narrow corridor develops, remains a bit uncertain. As confidence
    increases in the location of these storms, higher severe weather
    probabilities may be needed.


    ... Northwest Utah into Montana ...

    As the western mid-level low opens and takes on a negative tilt as
    it traverses the northwest periphery of the central US ridge,
    large-scale ascent will support scattered thunderstorm development
    across portions of northwest Utah, Idaho, and western Wyoming.
    Strong mid-level flow (around 50 knots at 500 millibars) coupled
    with a deep, well-mixed boundary layer will support downward
    momentum transfer within these thunderstorms capable of producing
    scattered wind damage. These storms will quickly move northeast into
    Montana during the evening hours. If coverage of these storms is
    greater than expected, higher wind probabilities would be warranted
    in subsequent outlooks.

    ..Marsh.. 09/05/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sun Sep 6 05:12:04 2026
    ACUS02 KWNS 060511
    SWODY2
    SPC AC 060510

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1210 AM CDT Sun Sep 06 2026

    Valid 071200Z - 081200Z

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

    ...SUMMARY...
    Strong to severe thunderstorms are possible across portions of the
    northern and central Plains into Minnesota on Monday.

    ...Northern Plains to Upper Midwest...

    An upper shortwave trough will develop eastward from the northern
    Rockies to the northern Plains on Monday. This will break down the
    upper ridge across the region, shifting it eastward toward the Great
    Lakes. At this occurs, strengthening mid/upper southwesterly flow
    will overspread the Plains. Southerly low-level winds will maintain
    a corridor of 60s to near 70 F dewpoints ahead of a surface low
    lifting northeast across the Dakotas. Warmer midlevel temperatures
    may result in capping for much of the day. However, as the upper
    trough approaching cooling aloft and increasing large-scale ascent
    should erode inhibition by late afternoon. Vertically veering wind
    profiles will foster effective shear magnitudes greater than 35 kt.
    Isolated to widely scattered storms will pose a risk for large hail
    and locally damaging gusts.

    A south/southwest low-level jet is forecast to increase during the
    evening. Though nocturnal cooling will resulting in increase
    inhibition after dark, warm advection aided by the strengthening
    low-level jet may result in one or more clusters of strong storms
    across the eastern portions of the Dakotas/Nebraska and into MN
    during the nighttime hours. It is uncertain if sufficient
    instability will persist overnight to support severe convection, but
    given the strength of mid/upper flow, some risk for damaging wind
    gusts could persist overnight.

    ..Leitman.. 09/06/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sun Sep 6 17:17:56 2026
    ACUS02 KWNS 061717
    SWODY2
    SPC AC 061716

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1216 PM CDT Sun Sep 06 2026

    Valid 071200Z - 081200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF THE NORTH-CENTRAL UNITED STATES...

    ...SUMMARY...
    Strong to severe thunderstorms are possible across portions of the
    northern and central Plains into Minnesota on Monday.

    ... Synopsis ...

    A mid-level shortwave trough will take on increasingly negative tilt
    on Monday as it lifts north-northeast along the northwest periphery
    of a central CONUS ridge. At the same time, a subtle, low-amplitude
    short-wave trough currently over the Pacific Ocean off the coast of
    Southern California will quickly move northeast ahead of the main
    wave.

    At the surface, an anticyclone over the Upper Great Lakes will
    maintain south-southeasterly flow across the Plains, sustaining mid-to-upper-60Fs dewpoints across the Missouri Valley into the
    Dakotas and western Minnesota. A weak low across eastern Montana
    will eventually redevelop northward into the Canadian Prairies
    overnight. As this happens, a cold front will move east across the
    Northern Plains.


    ... Northern Plains into the Upper Midwest ...

    The lead short-wave trough will be approaching the north-central US
    at the start of the forecast period (Monday morning). As the
    associated mid-level jet approaches, the low-level jet will increase
    and spread northward across the Plains. On the nose of this jet,
    elevated convection is likely to be ongoing in response to the
    warm-air advection. Latest model guidance maintains the low-level
    jet through the day and subsequently the morning convection is
    likely to persist through the day as it moves northeast toward
    western Minnesota. Although widespread cloud cover and moist
    mid-level profiles will limit instability, the degree of the
    cloud-layer shear will support at least some potential for hail with
    these elevated storms.

    To the southwest of the morning convection, clearing clouds will
    give way to robust heating allowing surface temperatures to climb
    into the upper-80Fs to mid-90Fs, with even hotter surface
    temperatures across western Nebraska. This will allow strong
    instability to develop by late afternoon ahead of the surface cold
    front/dry line.

    Isolated to perhaps scattered thunderstorms are possible during the
    afternoon along the surface front/dryline. However, low-level
    convergence along this boundary will be somewhat weak, with southerly/southwesterly flow ahead of it. At the same time,
    large-scale subsidence will likely be occurring in the wake of the
    morning convection. This should limit storm coverage across western
    South Dakota and western Nebraska. Northwest North Dakota and
    eastern Montana will be closer to the main wave as its associated
    better large-scale ascent. Thus, storm coverage may be slightly
    higher here during the afternoon. Isolated large hail and strong
    wind gusts will be possible with any of these storms.

    Overnight, the low-level jet increases in response to the main wave
    approaching the area. This should result in additional elevated
    thunderstorm development from northeast Nebraska into the eastern
    Dakotas. This activity should continue east across Minnesota through
    the overnight. Overall instability should be on the low side given
    the convection from the lead shortwave, but strong cloud-layer shear
    could support a hail and wind threat with the strongest elevated
    convection.

    ..Marsh.. 09/06/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Mon Sep 7 05:16:28 2026
    ACUS02 KWNS 070515
    SWODY2
    SPC AC 070513

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1213 AM CDT Mon Sep 07 2026

    Valid 081200Z - 091200Z

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

    ...SUMMARY...
    Strong to severe storms are possible on Tuesday from the central
    Plains into the Upper Midwest.

    ...Central Plains to Upper Midwest...

    An upper shortwave trough will move across the northern Plains and
    Upper Midwest on Tuesday. Enhanced mid/upper southwesterly flow will
    overspread the Mid-MO to Upper MS Valley as this occurs. Meanwhile,
    a surface low over Manitoba will lift northeast through the early
    Wednesday. A trailing cold front will sweep eastward across the
    Upper Midwest, with the southern extent of the boundary stalling
    over southern NE. Ahead of the front, a very moist airmass will be
    in place, supporting pockets of weak to moderate instability.

    Most forecast guidance depicts ongoing thunderstorms Tuesday morning
    across parts of MN/WI within a warm advection regime. This activity
    could pose a risk for hail and strong wind gusts. Early day
    thunderstorms could impact airmass recovery and destabilization for afternoon/evening severe potential ahead of the advancing cold
    front. If sufficient recovery occurs, another round of severe
    potential could develop from southeast MN into WI and the MI Upper
    Peninsula. Otherwise, severe potential will increase during the
    evening with southward extent ahead of the front across IA/eastern
    NE and perhaps northern KS. While vertical shear will lessen with
    southward extent, initial cells will likely develop into line
    segments along the front. An initial risk of hail and strong gusts
    will transition to mainly a damaging wind risk as storm mode becomes
    more linear.

    ..Leitman.. 09/07/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Mon Sep 7 17:48:16 2026
    ACUS02 KWNS 071747
    SWODY2
    SPC AC 071746

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1246 PM CDT Mon Sep 07 2026

    Valid 081200Z - 091200Z

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

    ...SUMMARY...
    Strong to severe storms are possible on Tuesday from the central
    Plains into the Upper Midwest.

    ...Central Plains to Upper Midwest...
    An upper-level shortwave trough currently translating through the
    northern Rockies will move into the Canadian Prairies and northern
    Plains on Tuesday. A secondary upper-level feature will translate
    from the northern Rockies to the northern Plains through the period.
    South of these features, enhanced mid-to upper-level southwesterly
    flow will overspread the Mid-Missouri and Upper Mississippi Valleys.
    At the surface, a low over Manitoba will lift northeastward into
    Ontario by early Wednesday. A trailing cold front will move eastward
    across the Upper Midwest while the southern extent of the boundary
    is forecast to stall over southern Nebraska.

    Ahead of the front, persistent southerly return flow will maintain a
    moist warm-sector with weak to moderate instability ahead of the
    front. Most CAM guidance depicts elevated thunderstorms Tuesday
    morning across parts of Minnesota and Wisconsin, near the nose of
    the low-level jet. This early activity will likely pose an initial
    risk for marginally severe hail and isolated strong wind gusts.

    Further south, severe potential is expected to gradually increase
    during the evening ahead of the front across Iowa, eastern Nebraska,
    and potentially northern Kansas. Deep-layer shear will progressively
    lessen with southward extent but strong convergence along the
    stalling boundary should support convective initiation within the
    moderately unstable boundary-layer. Initial cells will likely have a
    threat for isolated large hail and strong wind gusts, but are
    expected to quickly grow upscale into line segments with a greater
    damaging wind threat later Tuesday evening.

    ..Bentley.. 09/07/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Tue Sep 8 05:15:52 2026
    ACUS02 KWNS 080515
    SWODY2
    SPC AC 080513

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1213 AM CDT Tue Sep 08 2026

    Valid 091200Z - 101200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
    PLAINS TO THE EASTERN GREAT LAKES...

    ...SUMMARY...
    Isolated strong to severe thunderstorms are possible across portions
    of the central Plains to the eastern Great Lakes on Wednesday.

    ...Upper Ohio Valley and eastern Great Lakes...

    An upper trough will move from the Upper Midwest to the Great Lakes
    and Northeast on Wednesday. Stronger deep-layer flow will be focused
    across the Great Lakes and Northeast, to the north of a corridor of
    modest instability. As a surface cold front develops southeast
    toward the Ohio Valley and western NY during the evening, isolated
    to scattered thunderstorm development is expected. While modest
    instability will limit a more substantial severe risk, stronger
    deep-layer flow will support sporadic strong gusts.

    ...Central Plains to Lower Ohio Valley...

    Stronger instability is forecast within a moist and hot airmass from
    KS to the Lower MO and Lower OH Valleys Wednesday afternoon and
    evening. This area will remain well south of strong westerly flow
    aloft associated with the Great Lake upper trough, resulting in
    modest vertical shear, especial across KS. Despite modest shear,
    MLCAPE around 1500-2500 amid steeper low and midlevel lapse rates
    will support some risk of strong to severe convection. Storms
    developing along a surface boundary will mainly pose a risk for
    damaging gusts. Where marginally stronger shear will be located
    across the Lower MO Valley vicinity, small hail could also occur
    with the strongest updrafts.

    ..Leitman.. 09/08/2026

    $$

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Tue Sep 8 17:10:42 2026
    ACUS02 KWNS 081710
    SWODY2
    SPC AC 081708

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1208 PM CDT Tue Sep 08 2026

    Valid 091200Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN OHIO
    INTO WESTERN NEW YORK...

    ...SUMMARY...
    Isolated strong to severe thunderstorms are possible across portions
    of the central Plains to the Ohio Valley on Wednesday. A more
    organized severe weather threat is expected from eastern Ohio to
    western New York.

    ...Eastern Ohio into western New York...
    A mid-level trough will move from the Upper Midwest to the Northeast
    on Wednesday with moderate mid-level flow expanding along the
    southern periphery of this trough. A strong surface low associated
    with this trough will move across northern Ontario with a cold front
    extending into the Midwest. Ahead of this front, low 70s dewpoints
    are forecast to advect northward across Ohio, Pennsylvania, and
    western New York. Mid-level lapse rates will be relatively weak, but
    the moist environment will support moderate instability amid
    moderate effective shear. A line of storms is forecast to develop
    along the front from central Ohio into western New York. This
    environment should support damaging winds. Some tornado threat may
    exist as the low-level flow strengthens during the afternoon with
    clockwise curved low-level hodographs. However, a mostly linear
    storm mode should limit the overall tornado threat.

    ...Ohio Valley to the central Plains...
    Moderate instability is forecast to develop from the central Plains
    to the Ohio Valley. Across the plains, instability will be driven by
    a hot, deeply mixed environment while instability farther east will
    be driven by 70s dewpoints. Within this entire zone, mid-level flow
    is expected to remain quite weak which will limit storm
    organization. Water-loaded downbursts farther east and drier
    microbursts in the mixed environment farther west will be the
    primary hazard within the Marginal Risk. A zone of greater
    instability from eastern Missouri into western Indiana could support
    an isolated hail threat, particularly if some of this greater
    instability can spread beneath stronger mid-level flow. However,
    morning convection/cloudcover may be present where this most
    favorable environment could develop.

    ..Bentley.. 09/08/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Wed Sep 9 05:19:18 2026
    ACUS02 KWNS 090519
    SWODY2
    SPC AC 090517

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1217 AM CDT Wed Sep 09 2026

    Valid 101200Z - 111200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    THE SOUTHERN HIGH PLAINS...AND PARTS OF THE OZARKS TO THE
    MID-SOUTH...

    ...SUMMARY...
    Isolated strong to severe thunderstorms are possible on Thursday
    afternoon across the southern High Plains and portions of the Ozarks
    into the Mid-South.

    ...Southern High Plains to the Mid-South...

    An upper shortwave trough will move from the central Plains into the
    Great Lakes and Ohio Valley on Thursday. At the surface, a front is
    forecast to extend across the Ohio Valley into the southern High
    Plains during the morning. The western extent of the boundary over
    the southern High plains will sag southward through the period into northern/central TX, while the eastern extent of the boundary stalls
    over the Mid-South into the Mid-Atlantic. A moist airmass will be in
    place near and south of the surface boundary. Pockets of weak to
    moderate instability are expected near the surface boundary, but
    will largely be modulated by areas of ongoing precipitation at the
    beginning of the period, as well as weak midlevel lapse rates.

    Low-level flow is expected to remain weak, while strong flow aloft
    will be offset from stronger instability ahead of the surface front.
    This will limit more focused/robust severe potential. However, a few
    strong storms could occur across the southern High Plains within the post-frontal upslope flow regime where vertically veering wind
    profiles could support around 25-30 kt effective shear magnitudes.
    Marginal hail and gusty winds could occur within this regime.

    Within the very moist and moderately unstable airmass further east
    across portions of the Ozarks and Mid-South, sufficient clustering
    could occur to promote sporadic strong wind gusts via storm/outflow interactions, or from wet microbursts within the high-PW and steeper
    low-level lapse rate environment.

    ..Leitman.. 09/09/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Wed Sep 9 17:25:50 2026
    ACUS02 KWNS 091725
    SWODY2
    SPC AC 091723

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1223 PM CDT Wed Sep 09 2026

    Valid 101200Z - 111200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE
    SOUTHERN HIGH PLAINS...AND OVER PARTS OF THE OZARKS TO MID-SOUTH...

    ...SUMMARY...
    Isolated strong to severe thunderstorms are possible Thursday
    afternoon across the southern High Plains and portions of the Ozarks
    and Mid-South.

    ...Synopsis...
    A progressive, positive-tilt trough will move from the Mid MS Valley
    across the OH Valley, with a surface high building in behind and
    extending westward into the Central Plains. The associated front
    will stall from the Ozarks into OK, with generally weak easterly
    surface winds across this region. This region will harbor upper 60s
    to lower 70s F dewpoints and support modest destabilization with
    marginal shear. Later in the day and overnight, temporary shortwave
    ridging will occur over the Northern Plains as a stronger and broad
    upper trough develops into the northern Rockies. This will induce
    southerly low-level winds across the Plains with a nocturnal
    low-level jet aiding moisture return into NE and SD.

    ...Southern High Plains...
    Modest mid to high level northwesterlies combined with moist
    southeast surface winds will result in around 35 kt deep-layer
    shear, conditionally supporting cellular activity. Storms will
    develop over northeast NM after 20Z, and will proceed southeastward
    into the far western TX Panhandle during the evening. Cells may
    initially produce hail over 1.00" diameter, with possible clustering
    supporting locally severe gusts.

    ...Ozarks and Mid-South...
    A band of 1500-2000 J/kg MUCAPE should develop along the front,
    which will also be along the southern periphery of the stronger
    winds aloft with the shortwave trough. Afternoon storms moving along
    this boundary could organize into a few small clusters, though shear
    will be minimal. However, strong heating just south of the boundary
    and steepening of low-level lapse rates may support locally damaging outflow/gusts.

    ..Jewell.. 09/09/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Thu Sep 10 05:40:56 2026
    ACUS02 KWNS 100540
    SWODY2
    SPC AC 100538

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1238 AM CDT Thu Sep 10 2026

    Valid 111200Z - 121200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
    NEBRASKA INTO THE UPPER MIDWEST...

    ...SUMMARY...
    Severe thunderstorms are possible across portions of Nebraska to the
    Upper Midwest late Friday afternoon into Friday night.

    ...Nebraska/eastern Dakotas/Minnesota/Wisconsin...

    An upper shortwave trough will move across the northern Plains and
    Upper Midwest on Friday. As this occurs, a belt of enhanced
    southwesterly flow will overspread the region, particularly from the
    Dakotas into MN/WI. Cooling aloft will also support steepening
    midlevel lapse rates atop a moistening boundary layer in which
    increasing southerly low-level flow will transport 60s dewpoints
    northward across the region. A surface low is forecast to develop
    and shift east across SD, with a surface cold front shifting
    southeast through period. This front will be oriented from northeast
    to southwest from northwest MN/eastern ND into central SD near the
    surface low by mid to late afternoon. A dryline will extend
    southward from the surface low over central SD through central NE.
    Corridors of moderate instability are forecast along/ahead of the
    front, and thunderstorm development is expected by late
    afternoon/early evening across northern MN.

    Vertically veering wind profiles will support initial supercell
    storms capable of all hazards, including damaging wind, large hail,
    and a couple of tornadoes. Some hail greater than 2 inch diameter is
    possible if supercell mode can be maintained. Given strong linear
    ascent along the surface boundary, and an increasing southwesterly
    low-level jet during the evening, initial supercells are likely to
    cluster and/or grow upscale into line of convection spreading
    east/northeast through the nighttime hours.

    Convective coverage is a bit more uncertain, and overall severe
    potential more conditional, with southward extent into eastern SD/IA
    and central NE. Large-scale ascent will be weaker further south, and
    this could be problematic for overcoming inhibition from warmer
    850-700 mb temperatures, especially through early evening. As the
    surface cold front overtakes the dryline in NE overnight, elevated
    convection could develop within a low-level warm advection regime.
    Whether storms develop during the early evening or overnight, some
    severe risk from damaging gusts and hail will be possible.

    ..Leitman.. 09/10/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Thu Sep 10 17:15:58 2026
    ACUS02 KWNS 101715
    SWODY2
    SPC AC 101715

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    Issued by 15th OWS Scott Air Force Base IL
    1215 PM CDT Thu Sep 10 2026

    Valid 111200Z - 121200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
    NEBRASKA INTO THE UPPER MIDWEST...

    ...SUMMARY...
    Severe thunderstorms are possible across portions of Nebraska to the
    Upper Midwest late Friday afternoon into Friday night.

    ...Nebraska/Iowa/eastern Dakotas/Minnesota/Wisconsin...

    An upper shortwave trough will move across the northern Plains and
    Upper Midwest on Friday. As this occurs, a belt of enhanced
    southwesterly flow will overspread the region, particularly from the
    Dakotas into MN/WI. Cooling aloft will also support steepening
    midlevel lapse rates atop a moistening boundary layer in which
    increasing southerly low-level flow will transport 60s dewpoints
    northward across the region. A surface low is forecast to develop
    and shift east across SD, with a surface cold front shifting
    southeast through period. This front will be oriented from northeast
    to southwest from northwest MN/eastern ND into central SD near the
    surface low by mid to late afternoon. A dryline will extend
    southward from the surface low over central SD through central NE.
    Corridors of moderate instability are forecast along/ahead of the
    front, and thunderstorm development is expected by late
    afternoon/early evening across northern MN.

    Vertically veering wind profiles will support initial supercell
    storms capable of all hazards, including damaging wind, large hail,
    and a couple of tornadoes. Some hail greater than 2 inch diameter is
    possible if supercell mode can be maintained. Given strong linear
    ascent along the surface boundary, and an increasing southwesterly
    low-level jet during the evening, initial supercells are likely to
    cluster and/or grow upscale into line of convection spreading
    east/northeast through the nighttime hours.

    Convective coverage is a bit more uncertain, and overall severe
    potential more conditional, with southward extent into eastern SD/IA
    and central NE. Large-scale ascent will be weaker further south, and
    this could be problematic for overcoming inhibition from warmer
    850-700 mb temperatures, especially through early evening. As the
    surface cold front overtakes the dryline in NE overnight, elevated
    convection could develop within a low-level warm advection regime.
    Whether storms develop during the early evening or overnight, some
    severe risk from damaging gusts and hail will be possible.

    ..15_ows.. 09/10/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Thu Sep 10 17:41:42 2026
    ACUS02 KWNS 101741
    SWODY2
    SPC AC 101715

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    Issued by 15th OWS Scott Air Force Base IL
    1215 PM CDT Thu Sep 10 2026

    Valid 111200Z - 121200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
    NEBRASKA INTO THE UPPER MIDWEST...

    ...SUMMARY...
    Severe thunderstorms are possible across portions of Nebraska to the
    Upper Midwest late Friday afternoon into Friday night.

    ...Nebraska/Iowa/eastern Dakotas/Minnesota/Wisconsin...

    An upper shortwave trough will move across the northern Plains and
    Upper Midwest on Friday. As this occurs, a belt of enhanced
    southwesterly flow will overspread the region, particularly from the
    Dakotas into MN/WI. Cooling aloft will also support steepening
    midlevel lapse rates atop a moistening boundary layer in which
    increasing southerly low-level flow will transport 60s dewpoints
    northward across the region. A surface low is forecast to develop
    and shift east across SD, with a surface cold front shifting
    southeast through period. This front will be oriented from northeast
    to southwest from northwest MN/eastern ND into central SD near the
    surface low by mid to late afternoon. A dryline will extend
    southward from the surface low over central SD through central NE.
    Corridors of moderate instability are forecast along/ahead of the
    front, and thunderstorm development is expected by late
    afternoon/early evening across northern MN.

    Vertically veering wind profiles will support initial supercell
    storms capable of all hazards, including damaging wind, large hail,
    and a couple of tornadoes. Some hail greater than 2 inch diameter is
    possible if supercell mode can be maintained. Given strong linear
    ascent along the surface boundary, and an increasing southwesterly
    low-level jet during the evening, initial supercells are likely to
    cluster and/or grow upscale into line of convection spreading
    east/northeast through the nighttime hours.

    Convective coverage is a bit more uncertain, and overall severe
    potential more conditional, with southward extent into eastern SD/IA
    and central NE. Large-scale ascent will be weaker further south, and
    this could be problematic for overcoming inhibition from warmer
    850-700 mb temperatures, especially through early evening. As the
    surface cold front overtakes the dryline in NE overnight, elevated
    convection could develop within a low-level warm advection regime.
    Whether storms develop during the early evening or overnight, some
    severe risk from damaging gusts and hail will be possible.

    ..15_ows.. 09/10/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Fri Sep 11 05:02:30 2026
    ACUS02 KWNS 110501
    SWODY2
    SPC AC 110500

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1200 AM CDT Fri Sep 11 2026

    Valid 121200Z - 131200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE SATURDAY
    AFTERNOON AND EVENING ACROSS PARTS SOUTHEASTERN
    NEBRASKA...SOUTHWESTERN IOWA...NORTHEASTERN KANSAS AND MUCH OF
    NORTHWESTERN INTO CENTRAL MISSOURI...

    ...SUMMARY...
    Isolated severe storms, and perhaps at least a small organizing
    cluster of storms, appear possible across parts of the lower
    Missouri Valley late Saturday afternoon into Saturday night.

    ...Discussion...
    Downstream of a blocking mid-level high, which will likely be
    maintained to the southeast of the Aleutians through this period,
    models indicate that another vigorous digging short wave trough will
    contribute to lower/mid-tropospheric cyclogenesis offshore of the
    Pacific Northwest, before slowly pivoting inland Saturday through
    Saturday night. Farther east, it appears that attempts at building
    ridging across the northern Rockies into adjacent Great Plains will
    be suppressed by a digging short wave trough across the central
    Canadian/U.S. border vicinity, within the southwestern periphery of larger-scale troughing east of the Canadian Prairies through the
    Canadian Maritimes.

    By 12Z Saturday, perhaps the strongest short wave perturbation
    within the eastern Canadian troughing is forecast to be in the
    process of digging near the southwestern shores of Hudson Bay. As
    this feature turns eastward during the day, renewed cyclogenesis is
    forecast to the southeast of the primary surface cyclone, across
    northern Quebec. A cold front trailing to the southwest may advance
    across much of the upper Great Lakes, Upper Midwest and northern
    Great Plains by late Saturday night, preceded by a weaker cool
    surge, perhaps reinforced by convective outflow, across the lower
    Missouri Valley and central Great Plains.

    It does appear that southern mid- to subtropical latitude ridging
    will remain prominent across much of the central/southern Great
    Plains through Southeast into early Sunday. Within and near the
    northern periphery of this feature, a weak perturbation initially
    migrating east of the mid/lower Mississippi Valley is forecast to
    become increasingly sheared across the Appalachians through
    Northeast.

    ...Parts of central Great Plains/lower Missouri Valley...
    Stronger warm sector low-level wind fields and forcing for ascent
    are generally forecast to remain in closer proximity to the primary
    and secondary surface cyclones, to the Canadian side of the
    international border through this period. However, in the wake of
    the shearing perturbation to the east of the Mississippi Valley,
    models continue to suggest that forcing for ascent aided by lower/mid-tropospheric warm, beneath a difluent regime near/just
    south of the mid-level westerlies, may provide a focus for strong
    thunderstorm development Saturday through Saturday night.

    By early Saturday, it appears that this may set up across the lower
    Missouri Valley vicinity, where a zone of stronger differential
    surface heating may evolve by late Saturday afternoon. Seasonably
    high boundary-layer moisture near the interface of the stronger
    heating, beneath a plume of elevated mixed-layer air, may support a
    corridor of large mixed-layer CAPE on the order of 2000-3000+ J/kg.
    Coinciding with at least modest deep-layer shear, aided by
    pronounced veering of winds with height in lower to mid-levels, this
    regime may become conducive to the development of isolated to widely
    scattered supercells. It is possible that stronger activity
    persisting into Saturday evening could grow upscale into an
    organizing southeastward propagating cluster, near the nose of a
    modestly strengthening southwesterly nocturnal boundary-layer jet.


    Due to substantive continuing spread within and among the various
    model output, including the latest available convection-allowing
    guidance, severe probabilities have been maintained at 5 percent.
    However, this could still change in later outlooks for this period.

    ..Kerr.. 09/11/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Fri Sep 11 17:28:46 2026
    ACUS02 KWNS 111728
    SWODY2
    SPC AC 111726

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1226 PM CDT Fri Sep 11 2026

    Valid 121200Z - 131200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    THE CENTRAL PLAINS...AND FROM OHIO/WEST VIRGINIA INTO PARTS OF
    WESTERN PENNSYLVANIA...

    ...SUMMARY...
    Widely scattered strong to severe storms may develop Saturday
    afternoon and evening over parts of the Central Plains. Isolated
    activity may also affect parts of the Upper Ohio Valley into western Pennsylvania.

    ...Central Plains...
    Substantial forecast uncertainty exists on Saturday given the subtle
    forcing mechanisms at play. In general, sporadic severe storms
    appear will be possible as instability becomes strong south of a
    cold front from eastern KS into northwest OK where temperatures will
    become hot with minimal CIN. Even near/north of the cold front (into
    southeast NE, southern IA, northern MO), elevated instability may
    favor large hail. Overall lapse rate profiles will be steep,
    favoring both hail and wind, with sufficient mid to high level winds
    and deep-layer shear. Low-level winds will remain weak, and may
    favor highly deviant storm/cluster motions through the evening.

    ...Eastern OH/WV into western PA...
    A weak midlevel wave is forecast to move across the region, with
    around 35 kt winds at 500 mb. Dry air will exist northeast of the
    region, but surface pressures will drop with increasing low-level
    moisture out of the south and mid to upper 60s F dewpoints
    developing. Storms are generally forecast to develop over OH and
    northeast KY, spread east across WV and western PA. Given the
    increasing wind speeds and somewhat favorable low-level shear, some
    of the storms could eventually produce damaging gusts, most likely
    as peak instability is achieved.

    ..Jewell.. 09/11/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Sat Sep 12 05:11:08 2026
    ACUS02 KWNS 120510
    SWODY2
    SPC AC 120509

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1209 AM CDT Sat Sep 12 2026

    Valid 131200Z - 141200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SUNDAY AFTERNOON
    AND EVENING IN A CORRIDOR FROM WESTERN NEW ENGLAND THROUGH THE UPPER
    OHIO VALLEY...

    ...SUMMARY...
    Scattered strong storms accompanied by small to marginally severe
    hail and potential for locally damaging wind gusts may impact parts
    of the Northeast through upper Ohio Valley Sunday afternoon and
    evening.

    ...Discussion...
    Latest model output suggests that the initially notable mid-level
    low inland of the Pacific Northwest coast by 12Z Sunday may be
    slower to devolve into an open short wave trough. However, it still
    is forecast to remain progressive, slowly accelerating northeastward
    across the northern U.S. Rockies, in advance of a short wave impulse
    digging toward the northwestern Canadian Prairies. Within the
    downstream westerlies, models indicate that short wave ridging will
    build across much of the northern U.S. Great Plains through Upper
    Midwest, and adjacent portions of the southeastern Canadian Prairies
    through northwestern Ontario, while downstream troughing digs across
    Quebec and the lower Great Lakes region into Northeast.

    It appears that the primary surface cyclone associated with eastern
    troughing may migrate from northern Quebec into the Labrador Sea by
    late Sunday night. However, another surface low may begin to
    form/consolidate near/northeast of coastal northern New England,
    with a trailing cold advancing southeast of the lower Great Lakes
    region into the northern Atlantic Seaboard through Allegheny Plateau
    by the end of the period. Westward through the Ohio and middle
    Mississippi Valleys into the central Great Plains, it appears that
    this front may stall south of the stronger westerlies, with a cool
    surface high maintaining influence across much of the northern into
    central Great Plains until it centers shifts east of the upper
    Mississippi Valley late Sunday night.

    ...Parts of western New England into the Ohio Valley...
    In the wake of a sheared mid-level perturbation shifting across and
    east of the northern and middle Atlantic Seaboard during the day,
    low-level convergence and destabilization ahead of the main cold
    front advancing to the southeast of the lower Great Lakes region
    remains unclear. However, both HREF and REFS calibrated
    thunderstorm guidance suggest at least widely scattered thunderstorm development is probable by or shortly after peak heating Sunday,
    from the lee of the lower Great Lakes through the upper Ohio Valley.
    It is possible that this may coincide with sufficient strengthening
    of westerly flow in the 700-500 mb layer to support modestly
    organizing thunderstorm activity with potential to produce
    marginally severe hail and localized damaging wind gusts, before
    weakening Sunday evening.

    ...North central Great Plains/Middle Missouri Valley vicinity...
    Latest model output continues to exhibit substantive spread
    concerning convective potential across the region through this
    period. It now appears probable that at least a shallow relatively
    cool/stable boundary layer will remain entrenched as far south and
    west as Kansas into the northern high plains, beneath warming
    elevated mixed-layer air advecting north-northeast of the higher
    terrain. Forcing for ascent downstream of the approaching mid-level
    low/trough may support increasing thunderstorm development across
    the Dakotas Sunday night. However, based on forecast soundings,
    this may be rooted within/above the elevated mixed-layer, with weak
    CAPE limiting potential for severe hail.

    ..Kerr.. 09/12/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Sat Sep 12 17:00:18 2026
    ACUS02 KWNS 121700
    SWODY2
    SPC AC 121658

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1158 AM CDT Sat Sep 12 2026

    Valid 131200Z - 141200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE OHIO
    VALLEY TO THE NORTHEAST...

    ...SUMMARY...
    Scattered strong storms accompanied by small to marginally severe
    hail and potential for locally damaging wind gusts may impact parts
    of the Northeast through upper Ohio Valley Sunday afternoon and
    evening.

    ...Ohio Valley to the Northeast...
    A mid-level shortwave trough will amplify as it moves from the Upper
    Midwest to the eastern Great Lakes on Sunday. A primary surface low
    will move across Quebec with a cold front extending into the eastern
    Great Lakes. In addition, a lee trough will develop east of the
    Appalachians with weak surface low development along the coast.

    A large area of showers and embedded thunderstorms will likely be
    ongoing at the beginning of the period across the Mid-Atlantic to
    the Northeast. West of this activity, modest heating and mid 60s
    dewpoints will support weak to potentially moderate instability.
    This instability, combined with moderate to strong deep-layer shear
    will support the potential for strong to severe storms. However,
    storm coverage remains uncertain. A warm nose around 2km should
    limit storm development away from the front. Even along the front,
    storm coverage/intensity remains uncertain. Convergence will not be
    that strong as the surface low-develops along the coast. Therefore,
    a conditional severe weather environment remains from the Ohio
    Valley to the Northeast, but concerns with storm coverage preclude
    anything more than a Marginal Risk at this time.

    ...Central High Plains...
    Lee troughing will strengthen across the central Plains Sunday
    afternoon. As this occurs, upslope flow will strengthen across
    eastern Wyoming and vicinity. A cluster of storms will likely
    develop during the evening and move across South Dakota during the
    overnight period. Marginal instability will likely preclude any
    severe weather potential with this activity.

    ...North-central Montana...
    A mid-level jet streak will eject northeast from the base of a
    mid-level trough across the Northwest and overspread western
    Montana. Showers and a few thunderstorms will develop across western
    Montana during the afternoon and evening amid modest surface
    heating. Strong flow above 3km may occasionally mix to the surface
    with some gusty winds. If greater heating/instability can develop,
    an isolated severe wind threat may be possible with the strongest
    storms.

    ..Bentley.. 09/12/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Sun Sep 13 04:44:50 2026
    ACUS02 KWNS 130444
    SWODY2
    SPC AC 130442

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1142 PM CDT Sat Sep 12 2026

    Valid 141200Z - 151200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE MONDAY
    AFTERNOON INTO EVENING ACROSS PARTS OF EASTERN NEBRASKA INTO WESTERN
    AND CENTRAL IOWA...

    ...SUMMARY...
    An isolated severe thunderstorm or two, and perhaps a small
    organizing cluster of storms, may impact parts of eastern Nebraska
    into western Iowa late Monday afternoon into early evening.

    ...Discussion...
    Latest model output remains generally unchanged from prior runs
    concerning the large-scale pattern evolution through this period.
    To the east of a still fairly prominent mid-level high slowly
    beginning to shift eastward across the northeastern Pacific, a
    number of short wave perturbations are forecast to dig through
    multiple branches of westerlies across the Pacific coast and higher
    latitudes of northwestern North America into the Canadian Prairies.

    As this occurs, and downstream mid/upper ridging becomes
    increasingly prominent across the southern Great Plains through
    lower Great Lakes and north Mid Atlantic Seaboard, a notable remnant
    mid-level cyclonic circulation is forecast to accelerate more
    rapidly east-northeast of the northern U.S. Rockies, across the
    international border into northwestern Ontario by late Monday night.
    It appears that this will be accompanied by fairly significant
    surface cyclogenesis, and considerable strengthening of south to
    southwesterly lower/mid-tropospheric wind fields across much of the
    northern U.S. Great Plains through Upper Midwest/Great Lakes region.

    While an associated increase in vertical shear will contribute to an environment conditionally supportive of organized severe weather
    potential, destabilization within the evolving warm sector remains
    much more uncertain. Fairly widespread weak, elevated convection
    may overspread much of the northern Great Plains and middle to lower
    Missouri through Upper Midwest and adjacent Great Lakes region,
    reinforcing a relatively cool/stable boundary-layer to the north of
    a stalled surface frontal zone across the lower Missouri Valley
    through central Great Plains, before it begins to retreat northward.

    ...Southern Mid Missouri Valley into central Great Plains...
    There does appear a general consensus within/among the model output
    that the northward retreating low-level baroclinic zone may reach
    the southern fringe of the westerlies, across parts of Nebraska
    through Iowa by late Monday afternoon. It appears possible that
    boundary-layer moistening will contribute to a corridor of
    destabilization supportive of scattered vigorous thunderstorm
    development through the late afternoon and evening.

    Particularly where the southern periphery of a strong southerly
    low-level jet impinges on this front, across the eastern Nebraska
    into western Iowa vicinity, at least some guidance continues to
    suggest a scenario where the environment could become supportive of
    the evolution of an isolated intense supercell into small upscale
    growing cluster for a period late Monday afternoon into evening.

    ..Kerr.. 09/13/2026

    $$

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  • From COD Weather Processor @1:2320/107 to All on Sun Sep 13 17:31:20 2026
    ACUS02 KWNS 131731
    SWODY2
    SPC AC 131729

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1229 PM CDT Sun Sep 13 2026

    Valid 141200Z - 151200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
    NEBRASKA INTO WESTERN IOWA...

    ...SUMMARY...
    Scattered strong to severe thunderstorms may impact parts of eastern
    Nebraska into western Iowa late Monday afternoon into early evening.

    ...Discussion...
    A mid-level trough will move across the northern Plains on Monday
    with a strengthening 60-70 knot mid-level jet streak. The surface
    pattern will feature a surface low across the Canadian Prairies and
    a secondary weaker surface low across the central Plains. A moist
    airmass will advect northward to the east of the surface trough with
    mid to upper 60s dewpoints advecting into Nebraska and Iowa.

    Thunderstorms will likely be ongoing at the beginning of the period
    across eastern South Dakota and Minnesota into Iowa amid moderate
    isentropic ascent. In the wake of this morning activity, northward
    recovery will occur across northeast Kansas into southeast Nebraska
    and southwest Iowa. Within this zone, a narrow period of favorable
    conditions is forecast to develop ahead of front from southeast
    Nebraska northward. Most guidance shows storms developing within an
    environment featuring 2500+ J/kg MLCAPE and 30 to 35 knots of
    effective shear during the afternoon. This would support a supercell
    storm mode. If this discrete storm mode can be maintained, a EF2+
    tornado threat will exist given the nearly purely streamwise
    vorticity in the lowest 2km from RAP forecast soundings in the
    region. Limiting factors to this scenario are multiple storms
    developing along the front and quickly growing upscale and a lack of
    strong venting flow aloft which may result in disruptive downbursts
    before a more organized, strong low-level mesocyclone can develop.

    Farther southwest, moderate instability and strong heating/lapse
    rates may support isolated damaging wind gusts. Some guidance shows
    ~30 knots of effective shear which could support some marginally
    rotating storms. If this occurs, some isolated large hail may be
    possible. The 5% hail probability has been extended southwestward to
    account for this threat.

    Elevated thunderstorms will persist into the overnight period across
    southern Wisconsin and northern Illinois within a strong low-level
    jet and isentropic ascent. However, only modest elevated instability
    and limited cloud-bearing shear should preclude much severe threat
    farther east into southern Wisconsin and northern Illinois.

    ..Bentley.. 09/13/2026

    $$

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