• MESO: Mesoscale Discussion 1584

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Fri Jul 12 20:57:01 2024
    ACUS11 KWNS 122056
    SWOMCD
    SPC MCD 122056=20
    NDZ000-SDZ000-MTZ000-122300-

    Mesoscale Discussion 1584
    NWS Storm Prediction Center Norman OK
    0356 PM CDT Fri Jul 12 2024

    Areas affected...Far northeastern Montana...western North
    Dakota...and far northwestern South Dakota

    Concerning...Severe potential...Watch unlikely=20

    Valid 122056Z - 122300Z

    Probability of Watch Issuance...20 percent

    SUMMARY...Widely scattered thunderstorms are expected to develop
    over the next 1-2 hours across portions of western ND, far
    northeastern MT, and far northwestern SD. Severe wind gusts near
    65-76 mph, hail up to 1.5-2.0" in diameter, and perhaps a landspout
    tornado or two will be possible with the stronger thunderstorms.

    DISCUSSION...Diurnal heating across the northern plains has resulted
    in very warm temperatures in the low to upper 90s developing this
    afternoon. This, combined with surface dewpoints in the low 70s east
    of a surface trough/quasi-stationary warm front below steep
    mid-level lapse rates, is yielding 1500-3000 J/kg of MLCAPE. Recent
    satellite imagery shows increasing cumulus beginning to develop
    along the aforementioned trough. In addition, convective initiation
    has already taken place near Manning, ND. Increasing mid-level flow
    throughout late this afternoon into early this evening will likely
    support some thunderstorm organization and the potential for a few
    supercells.

    Thunderstorm coverage is expected to slowly increase late this
    afternoon, as destabilization continues under cooler temperatures
    aloft, subtle DCVA impacts the area, and surface convergence is
    enhanced. Considering large dewpoint-temperature spreads further
    west near the MT/ND border, damaging wind gusts appear more likely
    there, although a few instances of large hail cannot be ruled out
    through early this evening. Increasing low level helicity via backed
    surface flow with time, along with some enhanced stretching, could
    also support a landspout or two before sunset. Although a watch does
    not appear likely at this time due to an uncertainty in severe
    thunderstorm coverage, convective trends will be monitored closely
    over the next 1-2 hours.

    ..Barnes/Hart.. 07/12/2024

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!_RTZviAhfaqi-O6CfG48QwbJ23tozwjNlKewLjV4xd9JsmDsixfvjpZbGu7Iou4ScVJ8eyXS2= 3Yrf9CC4PcS0rh35vo$ for graphic product...

    ATTN...WFO...ABR...BIS...UNR...BYZ...GGW...

    LAT...LON 46920434 47680556 48480593 48910571 49010481 48990386
    48920285 48320199 47280116 46220052 45280096 44920207
    45570383 46920434=20


    =3D =3D =3D
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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Fri Jul 12 21:06:28 2024
    ACUS11 KWNS 122106
    SWOMCD
    SPC MCD 122105 COR
    NDZ000-SDZ000-MTZ000-122300-

    Mesoscale Discussion 1584
    NWS Storm Prediction Center Norman OK
    0405 PM CDT Fri Jul 12 2024

    Areas affected...Far northeastern Montana...western North
    Dakota...and far northwestern South Dakota

    Concerning...Severe potential...Watch unlikely=20

    Valid 122105Z - 122300Z

    CORRECTED FOR GRAPHIC

    Probability of Watch Issuance...20 percent

    SUMMARY...Widely scattered thunderstorms are expected to develop
    over the next 1-2 hours across portions of western ND, far
    northeastern MT, and far northwestern SD. Severe wind gusts near
    65-76 mph, hail up to 1.5-2.0" in diameter, and perhaps a landspout
    tornado or two will be possible with the stronger thunderstorms.

    DISCUSSION...Diurnal heating across the northern plains has resulted
    in very warm temperatures in the low to upper 90s developing this
    afternoon. This, combined with surface dewpoints in the low 70s east
    of a surface trough/quasi-stationary warm front below steep
    mid-level lapse rates, is yielding 1500-3000 J/kg of MLCAPE. Recent
    satellite imagery shows increasing cumulus beginning to develop
    along the aforementioned trough. In addition, convective initiation
    has already taken place near Manning, ND. Increasing mid-level flow
    throughout late this afternoon into early this evening will likely
    support some thunderstorm organization and the potential for a few
    supercells.

    Thunderstorm coverage is expected to slowly increase late this
    afternoon, as destabilization continues under cooler temperatures
    aloft, subtle DCVA impacts the area, and surface convergence is
    enhanced. Considering large dewpoint-temperature spreads further
    west near the MT/ND border, damaging wind gusts appear more likely
    there, although a few instances of large hail cannot be ruled out
    through early this evening. Increasing low level helicity via backed
    surface flow with time, along with some enhanced stretching, could
    also support a landspout or two before sunset. Although a watch does
    not appear likely at this time due to an uncertainty in severe
    thunderstorm coverage, convective trends will be monitored closely
    over the next 1-2 hours.

    ..Barnes/Hart.. 07/12/2024

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!91fwprTPwWl7h8YE9OoYqRx2OKIXup32Z2AY2IpdTXBjJ75qLHR7hN8EwrFxwcujF9UumlkTN= _amD6j0U8XNnyuun-A$ for graphic product...

    ATTN...WFO...ABR...BIS...UNR...BYZ...GGW...

    LAT...LON 46920434 47680556 48480593 48910571 49010481 48990386
    49040286 48760183 47400088 46220052 45280096 44920207
    45570383 46920434=20


    =3D =3D =3D
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

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