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  • DAY48SVR: Nws Storm Prediction Center Norman Ok

    From COD Weather Processor @1:2320/107 to All on Tue Sep 8 07:26:44 2026
    ACUS48 KWNS 080726
    SWOD48
    SPC AC 080724

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0224 AM CDT Tue Sep 08 2026

    Valid 111200Z - 161200Z

    ...DISCUSSION...
    ...Days 4-5/Fri-Sat -- Plains to the Great Lakes vicinity...

    Severe potential could develop across portions of the Plains into
    the Upper Midwest on Day 4/Friday as boundary layer moisture spreads
    northward ahead of a southeastward-advancing cold front. Moderate to
    strong destabilization ahead of the front, and enhanced vertical
    shear courtesy of a modest upper shortwave trough moving across the
    northern Plains/Upper Midwest vicinity, should be sufficient for
    organized convection mainly from Friday evening into early Saturday.

    Some severe potential could persist into Day 5 Saturday as the
    surface front stalls over the central/southern Plains vicinity but
    continues eastward across the upper Great Lakes region. A moist
    boundary layer will be in place, but stronger flow aloft will become
    increasing displaced to the north of stronger instability,
    precluding 15 percent delineation at this time.

    ...Days 6-8/Sun-Tue...

    An upper trough over the northwestern U.S. will develop eastward
    across the Plains and Great Lakes early next week. Another cold
    front will move across the area, and some severe potential could
    again sweep across the Plains to the Upper Midwest/Great Lakes
    vicinity. Medium range forecast guidance generally maintains
    stronger instability offset from enhanced flow aloft, partly due to
    the early cold frontal passage in the Day 4-5/Friday-Saturday time
    frame and strong surface high pressure over the Great Lakes in the
    wake of that frontal passage. Trends will be monitored and
    probabilities could become necessary in later outlooks.

    ..Leitman.. 09/08/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Wed Sep 9 07:29:22 2026
    ACUS48 KWNS 090729
    SWOD48
    SPC AC 090727

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0227 AM CDT Wed Sep 09 2026

    Valid 121200Z - 171200Z

    ...DISCUSSION...
    ...Day 4/Sat - Central Plains...

    A cold front will stall across the central Plains on Saturday.
    Low-level east/southeasterly flow will maintain rich boundary layer
    moisture across KS and into eastern CO. Early day convection may be
    ongoing in the vicinity of the stalled boundary within the low-level
    warm advection regime. It is uncertain if airmass recovery and
    renewed thunderstorm development will occur within the unstable warm
    sector given nebulous large-scale ascent and modest vertical shear.
    While low severe potential may eventually evolve, probability
    appears less than 15 percent at this time.

    ...Days 5-6/Sun-Mon -- Central Plains to the Great Lakes...

    An upper trough is forecast to move from the northern Rockies to the
    Great Lakes through early Day 7/Tuesday. This will bring enhanced
    southwesterly flow to portions of the northern/central Plains into
    the Great Lakes, particularly on Monday. With the approach of the
    trough, lee low development is forecast across the northern/central
    High Plains on Sunday. Increasing southerly low-level flow will
    transport moisture northward to NE/SD ahead of a
    southeastward-advancing cold front. This could support some severe
    risk across parts of the northern/central Plains and Mid-MO Valley
    vicinity on Sunday. However, large spread exists among forecast
    guidance with regards to the surface low placement, northward extent
    of moisture return, and frontal position. As a result, corridors of
    greater severe potential are uncertain on Sunday.

    As the upper trough continues to lift east/northeast through the
    Great Lakes on Monday, severe potential could develop eastward into
    parts of the Mid/Upper MS Valley and upper Great Lakes vicinity.
    Stronger deep-layer flow may become displaced to the north of better instability, and similarly large model spread continues into this
    time frame. Depending on trends, severe probabilities could
    eventually be needed for Sunday and/or Monday.

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

    Lower amplitude, quasi-zonal flow is expected to develop by the end
    of the forecast period as the early-week uppers shortwave trough
    lifts into eastern Canada and the sub-tropical high begins to
    rebuild over the southern U.S. This should largely limit severe
    potential, though abundant moisture will reside from the southern
    Plains into the Southeast and Mid-Atlantic and daily sporadic strong
    storms could still occur.

    ..Leitman.. 09/09/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Thu Sep 10 07:46:52 2026
    ACUS48 KWNS 100746
    SWOD48
    SPC AC 100744

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0244 AM CDT Thu Sep 10 2026

    Valid 131200Z - 181200Z

    ...DISCUSSION...
    ...Days 4-5/Sun-Mon -- Central Plains to the Mid-MS Valley...

    A progressive upper pattern is expected early in the week. An
    initial upper trough over the Great Lakes will spread east as upper
    ridging builds across the Plains. Meanwhile, another upper trough
    over the Northwest will shift east, moving across the northern
    Plains and Upper Midwest on Monday, breaking down the upper ridge.
    Surface high pressure over the Great Lakes on Sunday will suppress
    low-level moisture southward across the central/southern Plains and
    the Mid-MS/Lower OH Valleys. A very moist airmass will be in place
    to the south of a stalled frontal boundary across the region.
    Widespread showers and thunderstorms will be possible near the
    surface boundary within low-level warm advection over the Middle to
    Lower MO Valley. Vertical shear will be weak, but strong instability
    could some strong gust potential, though convection may stay mainly
    to the cool side of the surface boundary. Overall, severe potential
    appears less than 15 percent on Sunday.

    Severe potential will likely increase on Monday as the upper ridge
    breaks down and stronger southwesterly flow overspread the
    northern/central Plains to the Mid/Upper MS Valleys. Rich boundary
    layer moisture will be in place ahead of a southeastward-advancing
    cold front. Convection may be ongoing from the northern Plains into
    IA/IL Monday morning. This results in some uncertainty in position
    of best severe potential. Currently, the best overlap of rich
    boundary layer moisture, strong instability and favorable shear near
    the advancing cold front appears to be from eastern NE into IA and
    vicinity. A 40+ kt southwesterly low-level jet is expected to
    develop during the nighttime hours across KS/NE into IA, oriented
    along the surface front, supporting an organized line of storms
    tracking southeast ahead of the front, and promoting damaging wind
    potential. Overall, the pattern appears favorable for at least
    isolated severe storms on Monday, and a 15 percent delineation has
    been included.

    ...Days 6-8/Tue-Thu...

    The early week surface front will stall from the southern Plains to Mid-MS/Lower OH Valley through mid-week. A very moist airmass will
    persist south of the boundary, and persistent low-level warm
    advection could favor bouts of heavy rain. While some low-level
    severe potential could develop where pockets of strong
    destabilization occurs, weak vertical shear should largely limit
    more widespread potential, precluding probabilities.

    ..Leitman.. 09/10/2026

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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 11 09:02:12 2026
    ACUS48 KWNS 110901
    SWOD48
    SPC AC 110859

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0359 AM CDT Fri Sep 11 2026

    Valid 141200Z - 191200Z

    ...DISCUSSION...
    Medium-range guidance indicates that a remnant cyclonic circulation
    and associated mid-level troughing, likely accelerating across the
    northern U.S. Rockies and adjacent international border vicinity by
    early Monday, may be accompanied by substantive surface cyclogenesis
    across southern Manitoba through northwestern Ontario Monday through
    Monday night, before continuing east-northeastward into the higher
    latitudes. It appears that this will occur coincident with the
    transition to a more progressive regime across the northern
    mid-latitude Pacific, including the gradual suppression of a
    blocking high initially to the southeast of the Aleutians. It also
    appears likely to coincide with the redevelopment of rather
    prominent mid/upper ridging becoming centered across the Tennessee Valley/southern Appalachians vicinity, and increasingly influential
    across much of the central and eastern U.S. into the middle to
    latter portions of next week, before becoming suppressed and
    retrograding west-southwestward.

    In association with this regime, although there is some uncertainty
    concerning low-level moisture return and destabilization, it still
    appears that an evolving warm frontal zone could become a focus for
    organized strong to severe thunderstorm development across parts of
    the middle Missouri Valley toward Upper Midwest late Monday
    afternoon into Monday night. Thereafter, the potential for
    organized severe thunderstorm development appears generally low,
    though there may still be areas of strong storm development with
    rather isolated or marginal severe weather potential.

    ..Kerr.. 09/11/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sat Sep 12 08:43:44 2026
    ACUS48 KWNS 120843
    SWOD48
    SPC AC 120841

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0341 AM CDT Sat Sep 12 2026

    Valid 151200Z - 201200Z

    ...DISCUSSION...
    In the wake of a vigorous short wave perturbation and associated
    surface cyclone accelerating northeast of the upper Great Lakes into
    the higher latitudes, a lingering near-surface frontal zone across
    the lower Great Lakes and Ohio Valley into the central Great Plains
    may provide a focus for occasional thunderstorm development into the
    middle to latter portion of next week. However, this may largely
    remain beneath the northern periphery of initially prominent
    mid/upper ridging slowly beginning to retrograde from the Southeast
    toward the Southwestern international border area. Forcing for
    ascent and destabilization may not support more than rather isolated
    and/or marginal severe thunderstorm potential, and even latest
    available AI guidance generally suggests that this limited potential
    will wane by late week into next weekend.

    ..Kerr.. 09/12/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sun Sep 13 08:22:50 2026
    ACUS48 KWNS 130822
    SWOD48
    SPC AC 130820

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0320 AM CDT Sun Sep 13 2026

    Valid 161200Z - 211200Z

    ...DISCUSSION...
    Latest medium-range model output indicates that the initially
    prominent Southeastern mid-level ridge will slowly retrograde west-southwestward and become increasingly suppressed across the
    lower latitudes late this coming work week into next weekend.
    However, it appears that the evolving westerlies across the U.S.
    will remain modest to weak, with little potential for appreciable
    surface cyclogenesis. While guidance suggests some continuing
    potential for widely scattered strong thunderstorm development near
    a lingering frontal zone across the Ohio into lower Missouri Valley
    on Wednesday, it appears that this will diminish thereafter, with
    generally negligible risk for organized severe thunderstorm
    potential into and through next weekend.

    ..Kerr.. 09/13/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Mon Sep 14 08:56:30 2026
    ACUS48 KWNS 140856
    SWOD48
    SPC AC 140854

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0354 AM CDT Mon Sep 14 2026

    Valid 171200Z - 221200Z

    ...DISCUSSION...
    Latest medium-range model output continues to indicate that
    initially prominent Southeastern mid-level ridging will gradually
    become suppressed late this week into next weekend. However, short
    wave developments within the westerlies become more unclear by next
    weekend into early next week. In general, it appears that a modest
    to weak split flow will evolve across much of North America, as
    larger positive mid-level height anomalies tend to develop across
    interior Canada.

    It is possible that diurnal destabilization will remain sufficient
    to support areas of stronger daily thunderstorm development across
    the U.S., supported by forcing for ascent associated with these
    evolving perturbations. However, any associated severe weather
    seems unlikely to become particularly well organized and probably
    will remain rather isolated and/or marginal in nature.

    ..Kerr.. 09/14/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Tue Sep 15 08:44:30 2026
    ACUS48 KWNS 150844
    SWOD48
    SPC AC 150842

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0342 AM CDT Tue Sep 15 2026

    Valid 181200Z - 231200Z

    ...DISCUSSION...
    The latest medium-range model output still suggests that an
    initially prominent mid-level ridge, across the central and southern
    Great Plains through lower Ohio/Tennessee Valleys at the outset of
    the period, will become suppressed late this week into next weekend.
    But, this may be a bit slower to occur than previous guidance has
    suggested, and the coinciding and subsequent pattern evolution
    across much of North America has become more unclear due to model
    spread. In general, though, it still appears that modest to weak
    split westerlies will prevail, with little appreciable signal for
    substantive surface cyclogenesis. Barring appreciable change, the
    potential for organized severe thunderstorm development still
    appears low through at least early next week.

    ..Kerr.. 09/15/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Wed Sep 16 08:58:38 2026
    ACUS48 KWNS 160858
    SWOD48
    SPC AC 160856

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0356 AM CDT Wed Sep 16 2026

    Valid 191200Z - 241200Z

    ...DISCUSSION...
    Latest medium-range model output suggests that modest pre-frontal
    surface troughing across the Texas/Oklahoma Panhandle vicinity
    through south central/eastern Kansas, and perhaps the slow moving
    frontal zone across northeastern Kansas through northern
    Missouri/southeastern Iowa, may provide focus for scattered strong
    thunderstorm development late Saturday afternoon into evening. This
    may be supported by forcing for ascent downstream of weak
    larger-scale mid-level troughing slowly progressing across the
    Rockies into Great Plains, with deep boundary-layer mixing along the
    surface trough and higher boundary-layer moisture content along the
    frontal zone contributing to thermodynamic profiles potentially
    conducive to severe weather. However, with the belt of stronger lower/mid-tropospheric flow associated with a preceding impulse
    tending to weaken and/or shift eastward near or to the south of the
    Great Lakes region, it still appears that this potential will remain
    relatively isolated in coverage and/or marginal in nature.

    Thereafter, late this weekend through early next week, the spread
    among model output concerning the mid/upper flow evolution
    increases. However, even among the differing solutions, there is
    little readily apparent that indicates an increase in organized
    severe thunderstorm potential.

    ..Kerr.. 09/16/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Thu Sep 17 08:50:14 2026
    ACUS48 KWNS 170850
    SWOD48
    SPC AC 170848

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0348 AM CDT Thu Sep 17 2026

    Valid 201200Z - 251200Z

    ...DISCUSSION...
    The latest ECENS and GEFS appear similar in their depiction of the
    evolving mid/upper flow late this weekend through the middle of next
    week. A weak mid-level trough and embedded low emerging from the
    Intermountain West may weaken further while slowly progressing
    across the central Great Plains through Ohio Valley, to the south of
    a transient building mid-level high near the central Canadian/U.S.
    border into the upper Great Lakes/northwestern Ontario vicinity.
    Toward the middle to latter part of next week, remnant mid-level
    troughing may tend to dig into and across the Mid Atlantic, as
    mid-level ridging builds again across the Great Plains/Mississippi
    Valley, downstream of a weak mid-level perturbation progressing into
    the Southwest, and amplifying troughing within the stronger
    westerlies offshore of the Pacific coast.

    In association with this evolving regime, generally weak deep-layer
    mean wind fields and increasingly limited potential for stronger destabilization are likely to minimize the risk for severe weather.

    ..Kerr.. 09/17/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Fri Sep 18 08:22:30 2026
    ACUS48 KWNS 180822
    SWOD48
    SPC AC 180820

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0320 AM CDT Fri Sep 18 2026

    Valid 211200Z - 261200Z

    ...DISCUSSION...
    Initially zonal mid-level flow, with embedded low-amplitude impulses
    traversing the central CONUS early next week, will give way to
    gradual amplification of an upper ridge over the central U.S. The
    best chance for any severe thunderstorms will be on Day 4/Monday
    across the TN Valley, where a surface cold front, preceded by rich
    low-level moisture, will be slow to clear the region. Thereafter,
    drier low-level conditions will prevail across much of the central
    and eastern CONUS, with surface high pressure poised to settle over
    much of the U.S. between the MS River and the Appalachians, limiting
    the severe threat.

    ..Squitieri.. 09/18/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sat Sep 19 08:26:34 2026
    ACUS48 KWNS 190826
    SWOD48
    SPC AC 190824

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0324 AM CDT Sat Sep 19 2026

    Valid 221200Z - 271200Z

    ...DISCUSSION...
    An initially zonal mid-level flow regime will gradually transition
    to a more amplified upper-air pattern, characterized by ridging over
    the Plains states through the week into next weekend. As this
    occurs, low-level moisture will continue to be shunted southward as
    cooler mid-level temperatures remain relatively confined west of the
    Rockies, and flow aloft remains modest at best. As a result, there
    are no clear signals for an organized threat of severe thunderstorms
    across the CONUS for Days 4-8 (Tuesday-Saturday).

    ..Squitieri.. 09/19/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sun Sep 20 08:25:00 2026
    ACUS48 KWNS 200824
    SWOD48
    SPC AC 200823

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0323 AM CDT Sun Sep 20 2026

    Valid 231200Z - 281200Z

    ...DISCUSSION...
    Upper ridging will persist over the central U.S. through the
    forecast period, with a meandering upper trough evolving into a
    cut-off upper low off of the Mid-Atlantic Coast and an upper trough
    amplifying over the Interior West late this week into next weekend.
    Through the week, a relatively dry low-level airmass will settle
    east of the MS River and west of the Rockies, limiting the severe
    threat over the western and eastern third of the U.S. Some modest
    moisture return is likely across the Plains given lee troughing.
    However, upper support will be weak, which should limit the severe
    threat across the central U.S. as well. As such, no organized severe
    threats seem apparent for the CONUS Days 4-8 (Wednesday-Sunday).

    ..Squitieri.. 09/20/2026

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