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  • DAY48SVR: Nws Storm Prediction Center Norman Ok

    From COD Weather Processor @1:2320/107 to All on Mon Aug 17 13:45:52 2026
    ACUS48 KWNS 170750
    SWOD48
    SPC AC 170748

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0248 AM CDT Mon Aug 17 2026

    Valid 201200Z - 251200Z

    ...DISCUSSION...
    An amplified upper pattern will persist during the Day 4-8/Thu-Mon
    period. An upper trough will remain over the eastern U.S. while
    strong upper ridging spreads from the western U.S. toward the Plains
    late in the period. This pattern will result in moderate
    northwestern flow aloft across portions of the Plains into the
    Midwest. Beneath northwesterly flow aloft and on the eastern
    periphery of upper ridging, a seasonally moist airmass will be in
    place from the Mid/Lower MO Valley into the Upper/Middle MS Valley.
    Some severe potential could develop over these areas through the
    period. However, capping may limit this potential, and with no
    notable features fostering focused large-scale ascent, uncertainty
    is too high to include 15 percent severe probabilities at this time.

    ..Leitman.. 08/17/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Tue Aug 18 08:26:20 2026
    ACUS48 KWNS 180826
    SWOD48
    SPC AC 180824

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0324 AM CDT Tue Aug 18 2026

    Valid 211200Z - 261200Z

    ...DISCUSSION...
    For the Fri/D4 to Tue/D8 period, an upper ridge is forecast to
    expand from the Four Corners states into the Southern Plains, with
    northwest flow aloft over the Northern Plains shifting east across
    Midwest and into the Northeast.

    On Fri/D4, scattered storms may occur across the Central Plains and
    Cornbelt, with areas of moisture and instability beneath the 30-40
    kt northwest flow regime favor scattered hail or strong wind gusts. Predictability is low due to the likelihood of ongoing storms or
    convective systems early in the day, which may affect air mass
    quality and effective boundary positioning. However, the NE/KS/IA/MO
    region appears to be the most likely area for an eventual risk area.

    Also on Fri/D4, storms are again expected over parts of the Mid
    Atlantic to Carolinas, where 25 kt southwest flow in the midlevels
    and a surface trough will support scattered storm clusters producing
    locally damaging gusts. Areas of ongoing storms or outflows from the
    previous day's convection may have an impact here as well as far as
    the most favorable zones for additional severe storms.

    There may also be some potential on Sat/D5 to Sun/D6 over parts of
    the Mid Atlantic as cooling aloft with an upper trough moves across
    the area. Timing of this trough will be critical, as will the
    movement of the associated cold front.

    ..Jewell.. 08/18/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Wed Aug 19 08:30:38 2026
    ACUS48 KWNS 190830
    SWOD48
    SPC AC 190828

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0328 AM CDT Wed Aug 19 2026

    Valid 221200Z - 271200Z

    ...DISCUSSION...
    For the Sat/D4 to Wed/D8 period, an upper ridge will persist from
    the Southern Plains into the Southwest, while various shortwave
    troughs affect the northern Plains, Great Lakes, and Northeast. The
    primary trough amplification will occur from the Upper MS
    Valley/Great Lakes on Sat/D4 into the Northeast through Mon/D6, with
    moisture and instability supportive of strong storms generally
    persisting over parts of the Southeast and Mid Atlantic. Shear will
    remain weak over the East on Sat/D4, with areas of storms producing
    strong gusts, perhaps marginal/isolated severe. By Sun/D5, strong
    winds and cooling aloft will move across the Mid Atlantic and
    Northeast, though antecedent precipitation will affect the warm
    sector, as will veering low-level winds. Frontal timing will depend
    on the upper trough speed, and overall predictability is low for
    Sun/D5.

    To the west, daily corridors of thunderstorms are also likely over
    parts of the central to northern Plains, with northwest flow
    strongest on Sat/D4 and weakening into D5/D6. At least marginal
    risk/low probabilities are likely in later outlooks for isolated
    wind/hail.

    ..Jewell.. 08/19/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Thu Aug 20 08:31:18 2026
    ACUS48 KWNS 200830
    SWOD48
    SPC AC 200829

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0329 AM CDT Thu Aug 20 2026

    Valid 231200Z - 281200Z

    ...DISCUSSION...
    An upper trough will move slowly across the Northeast Sun/D4 into
    Mon/D5, with thunderstorms likely ahead of a cold front. This front
    will likely push offshore on Mon/D5 as a surface low ejects
    northward across Quebec. A moist air mass will remain ahead of the
    front across the Mid Atlantic and into New England, though ongoing
    rain and thunderstorms reduce predictability as far as how unstable
    it will become on Sun/D4. Also mitigating overall severe risk
    appears to be relatively modest low-level wind speeds, with 10-20 kt
    at 850 mb. These areas will be monitored for possible low severe
    probabilities in the coming days.

    To the west, low severe probabilities are possible over parts of the
    northern High Plains, as a small but progressive shortwave trough
    moves out of the Northwest and across the northern Rockies atop the
    upper ridge. West to northwest winds across the northern High Plains
    combined with a lee trough and ribbon of 2000 J/kg MUCAPE should
    support at least isolated hail/wind activity, perhaps from eastern
    MT into the Dakotas.

    Additional storm potential, generally low-end, will be possible
    Tue/D6 into Wed/D7 over much of the Midwest to Great Lakes, though predictability is quite low in forecasting the track of the northern
    wave, which may begin phasing with a developing upper low over
    Ontario.

    ..Jewell.. 08/20/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Fri Aug 21 08:56:24 2026
    ACUS48 KWNS 210856
    SWOD48
    SPC AC 210854

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0354 AM CDT Fri Aug 21 2026

    Valid 241200Z - 291200Z

    ...DISCUSSION...
    A mid-level trough will move across the Northeast on Monday and the
    surface front will be mostly offshore, reducing the severe weather
    threat. As this trough departs, ridging will build across the
    Rockies. This will eventually set up a pattern featuring individual
    mid-level shortwave troughs within northwesterly flow from the
    northern Plains to the Midwest. Some severe weather will likely
    occur with mid-level shortwave troughs within this flow, but these
    details likely will not become more clear until the short term.

    Model consensus indicates a stronger mid-level shortwave trough
    traversing the Pacific Northwest on D7/Thursday. This pattern would
    be favorable for some severe weather threat across Montana, but at
    this time, it appears moisture will stay farther east. Therefore, no
    severe weather is anticipated.

    ..Bentley.. 08/21/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sat Aug 22 07:44:26 2026
    ACUS48 KWNS 220744
    SWOD48
    SPC AC 220742

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0242 AM CDT Sat Aug 22 2026

    Valid 251200Z - 301200Z

    ...DISCUSSION...
    Overall, the long range pattern will feature a ridge centered over
    the southern High Plains which may shift slightly west through the
    period. Some severe weather may occur within the northwesterly flow
    pattern from the northern Plains to the Ohio Valley Tuesday/D4 to
    Thursday/D6, but confidence is not high enough for probabilities at
    this time. There is an emerging signal for a seasonably strong high
    pressure to build into the eastern CONUS and shunt most of the
    richer low-level moisture to the Gulf Coast states. If this occurs,
    a relative lull in severe weather potential would exist from the
    Mid-Atlantic and Northeast to the Upper Midwest into next weekend.

    ..Bentley.. 08/22/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sun Aug 23 08:41:00 2026
    ACUS48 KWNS 230840
    SWOD48
    SPC AC 230838

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0338 AM CDT Sun Aug 23 2026

    Valid 261200Z - 311200Z

    ...DISCUSSION...
    ...D4/Wednesday to D6/Friday...
    A mid-level trough will amplify across the Great Lakes region while
    the mid-level ridge maintains its amplitude across the Rockies.
    Within this pattern, some severe weather potential may exist as a
    cold front moves from the Great Lakes to the Northeast. However, the
    signal is not that strong and thus, it is unclear if more than an
    isolated threat will exist; but the evolution of this front and the
    instability associated with it will be monitored.

    ...D7/Saturday to D8/Sunday...
    There is still a fair amount of uncertainty with the evolution of
    the pattern by next weekend, but a general trend toward flattening
    of the upper-level ridge is apparent in the deterministic, AI, and
    ensemble guidance next weekend. This includes moderate flow within
    the zonal region across the central/northern Plains and into the
    Upper Midwest. This period will need to be watched closely as strong instability and moderate shear appear to overlap across a relatively
    broad region, which should support diurnal thunderstorm activity
    given the flattening of the ridge. The specific timing/location of
    these threats will depend on evolution of the pattern and the
    embedded shortwave troughs within the flow. However, it is worth
    noting that the EC-AIFS and the AIGFS both have a signal for a more consolidated mid-level shortwave trough moving across the northern
    Plains on Sunday/D8, which has also been consistently shown by the
    EC-AIFS for the past 4 runs. If this trend continues, there may be opportunities for probabilities to be added in later outlooks.

    ..Bentley.. 08/23/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Mon Aug 24 09:01:06 2026
    ACUS48 KWNS 240900
    SWOD48
    SPC AC 240859

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0359 AM CDT Mon Aug 24 2026

    Valid 271200Z - 011200Z

    ...DISCUSSION...
    A strong mid-level ridge will be centered over the Rockies on
    Thursday with a broad trough centered across the Great Lakes. The
    ridge will break down over the weekend with a more zonal flow with
    embedded shortwave troughs extending from the Northwest to the
    northern Plains and into the Northeast. Beyond this weekend,
    guidance differs on the evolution of the pattern with considerable
    uncertainty.

    ...D7/Sunday to D8/Monday - Northern Plains...
    Guidance continues to consolidate around an unseasonably strong
    mid-level shortwave trough across the northern Plains into the Upper
    Midwest on Sunday and Monday. There is still some spread around the
    timing of this trough and also the degree of destabilization ahead
    of it. However, despite these timing differences, a moderately
    strong signal for an increasing severe weather threat in this period
    appears to be emerging as a trough with a consistent convective
    signal is shown by the ECMWF and GFS and also by the AI-GFS and
    AI-ECMWF. Ensemble guidance shows a flattened ridge with a mid-level
    jet streak across this region during the same timeframe.
    Surprisingly, AI/ML guidance shows very little signal for a severe
    threat across this region. Analysis of individual ensemble members
    suggests this is likely reflective of the uncertainty in timing and
    location of this trough and greater spread among the ensemble
    guidance. Nonetheless, the potential for an organized severe weather
    threat across the northern Plains and/or Upper Midwest late this
    weekend into early next week appears to be increasing. If guidance
    continues to consolidate with decreasing spread about the timing of
    the trough, severe weather probabilities may eventually be needed.

    ..Bentley.. 08/24/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Tue Aug 25 08:30:18 2026
    ACUS48 KWNS 250829
    SWOD48
    SPC AC 250827

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0327 AM CDT Tue Aug 25 2026

    Valid 281200Z - 021200Z

    ...DISCUSSION...
    Severe weather is possible across the northern Plains into the Upper
    Midwest starting Day 4/Friday and continuing through the weekend.
    The specific evolution remains unclear with quite a range of
    ensemble solutions at this time. Nonetheless, expect severe weather
    somewhere within this broad region each day.

    ...Day4/Friday...
    As the upper-level ridge flattens on Friday, lee troughing will
    develop across the northern High Plains. Moderate to strong
    instability is forecast to develop across the western Dakotas ahead
    of this lee trough. Any weak mid-level shortwave trough to provide a
    focus for this threat remains nebulous. Therefore, the location of
    any surface features remains unclear and thus, it is difficult to
    highlight a more specific region with a greater severe weather
    probability at this time.

    ...Day5/Saturday...
    Severe weather may be possible across portions of the Upper Midwest
    on Saturday, but this threat will be somewhat dependent on the
    location and intensity of Day 4 convection.

    ...Day6/Sunday...
    The ECMWF and AI-ECMWF remain relatively consistent showing a trough
    traversing the northwest on Saturday and emerging across the
    northern Plains on Sunday. Meanwhile, the GFS and AI-GFS have
    trended more progressive, and the individual GEFS members show
    substantial spread in the upper-level pattern for Sunday/Day6. The
    relative consistency in timing and location of the upper-level
    trough from the ECMWF build confidence for this solution. However,
    even the ECMWF and AI-ECMWF trended slightly less amplified with
    this trough. Therefore, the combination of large spread in the upper
    pattern from GEFS members and a slightly deamplified trend from the
    ECMWF provide enough uncertainty to avoid adding probabilities at
    this time.

    ..Bentley.. 08/25/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Wed Aug 26 08:44:10 2026
    ACUS48 KWNS 260843
    SWOD48
    SPC AC 260842

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0342 AM CDT Wed Aug 26 2026

    Valid 291200Z - 031200Z

    ...DISCUSSION...
    ...D4/Saturday - Northern Plains to Upper Midwest...
    A mid-level ridge will move slowly east across the Plains with
    slight suppression through the day. A lee trough will consolidate
    into a surface low across the northern Plains through the day
    Saturday. Ahead of this surface low, strong instability is forecast
    across South Dakota and vicinity. Despite the favorable environment
    across this region, primary forcing will be focused on the nose of
    the low-level jet across Iowa and into Wisconsin, well east of the
    greatest instability and near the Canadian border. Therefore,
    limited storm coverage precludes severe weather probabilities at
    this time, but given the favorable environment, it will need to be
    monitored closely.

    ...D5/Sunday - North Dakota and Vicinity...
    A mid-level shortwave trough will move from the Pacific Northwest to
    the northern Plains Saturday/D4 and Sunday/D5. 00Z guidance has come
    into fairly consistent agreement with the location and amplitude of
    this trough across eastern Montana at 00Z Sunday evening. However,
    there is considerable disagreement with the degree of
    destabilization across North Dakota, where forcing will be greatest.
    The GFS dry bias across most of the Plains has severely lessened the instability. However, despite this challenge, it is apparent that
    most of the instability significantly southeast of the upper-level
    forcing. The GFS-Para seems to have a more realistic handle on
    low-level moisture/instability magnitude but it also shows a
    significant disconnect between where this instability is located and
    the deeper forcing.

    The deterministic ECMWF forecast shows a potentially significant
    severe weather event across North Dakota with strong instability and
    shear ahead of a robust convective QPF signal. This is supported by
    the AI-ECMWF which shows a similar evolution. However, the
    EC-ensemble mean of instability shows at least some trend toward the
    GEFS with primary instability southeast of the best forcing.

    It is also worth noting that the wave is forecast to eject across
    North Dakota relatively late (~06Z) which may be a somewhat limiting
    factor to a greater threat. This potential timing disconnect,
    combined with some hint of limited overlap between the greatest
    instability and the primary upper forcing, cast enough uncertainty
    to preclude severe weather probabilities at this time. However, it
    is worth noting that if a solution similar to the ECMWF
    materializes, a significant severe weather event is possible.

    ...D6 and Beyond...
    By early next week, the primary mid-level ridge appears to center
    around the southern Appalachians with broad southwesterly flow from
    the Southwest to the Great Lakes. Within this area of southwesterly
    flow, multiple embedded mid-level shortwave troughs are forecast. Predictability of these smaller scale features is relatively low at
    this range, but some continued severe weather threat will likely
    persist around the periphery of the ridge from the Plains to the
    Great Lakes and potentially into the Northeast.

    ..Bentley.. 08/26/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Thu Aug 27 08:00:42 2026
    ACUS48 KWNS 270800
    SWOD48
    SPC AC 270758

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0258 AM CDT Thu Aug 27 2026

    Valid 301200Z - 041200Z

    ...DISCUSSION...
    ...D4/Sunday - Northern Plains...
    Some severe weather is possible across the northern Plains on
    Sunday, but details remain unclear. The primary mid-level shortwave
    trough and associated large-scale ascent is expected to traverse
    northern Montana and North Dakota. However, the greater instability
    is focused farther southeast across eastern South Dakota and
    southwest Montana. The ECMWF shows enough instability developing
    farther north into south-central North Dakota to support some severe
    weather threat. The uncertainties regarding destabilization and
    storm coverage preclude severe weather probabilities at this time.

    ...D5 and Beyond...
    The forecast next week features multiple mid-level shortwave troughs
    and considerable uncertainty with the timing of these features.
    However, there is a larger scale trend toward a ridge building
    across the Plains with northwesterly flow from the Upper Midwest to
    the Mid-Atlantic/New England. Moderate to strong instability along
    this corridor will support some severe weather potential next week.
    However, specific areas of greater severe weather potential will
    depend on the timing and amplitude of embedded mid-level shortwave
    troughs. Therefore, no probabilities can be added at this time.

    ..Bentley.. 08/27/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)