• MESO: Mesoscale Discussion 0887

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Jun 8 20:40:13 2021
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    ACUS11 KWNS 082040
    SPC MCD 082039=20

    Mesoscale Discussion 0887
    NWS Storm Prediction Center Norman OK
    0339 PM CDT Tue Jun 08 2021

    Areas affected...Eastern Montana...western North Dakota

    Concerning...Severe potential...Watch likely=20

    Valid 082039Z - 082315Z

    Probability of Watch Issuance...80 percent

    SUMMARY...Significant hail and significant wind gusts will be
    possible as storms develop and intensify across eastern Montana and
    western North Dakota later this afternoon into the evening. A
    conditional threat for a couple tornadoes also exists. A WW is
    likely to be considered by 6 PM MDT.

    DISCUSSION...Mid-level ascent is evident on water-vapor imagery
    across parts of western Wyoming into southern Montana. Ahead of the
    shortwave trough, strong southeasterly winds continue to advect low
    to mid 60s F dewpoints into the western Dakotas and eventually into
    eastern Montana. Convective inhibition in eastern Montana is
    continuing to decrease given the deepening of cumulus near the North
    Dakota border. There is some uncertainty in the timing of storm
    initiation, but development along the higher terrain in
    south-central Montana is likely to occur earlier given proximity to
    the shortwave. Further development is also possible along the warm
    front in northeast Montana to near the North Dakota border. Steep
    mid-level lapse rates observed on the 19Z GGW sounding with 45-55
    kts of effective shear will promote organized storms capable of
    large to very large (2+ inches hail), at least initially.
    Temperature/dewpoint spreads and overall number of storms will
    likely lead to rather quick transition to clusters/bowing segments
    capable of severe wind gusts (some of which will exceed 65 kts).

    Low-level wind profiles near the warm front into northwest North
    Dakota are expected to remain favorable for tornadoes this
    afternoon, with even an increase in hodograph size this evening as
    850 mb wind strengthen. LCLs will not be particularly low, but areas
    near the warm front have seen greater cloud cover most of the day
    which will allow for relatively lower dewpoint depressions. The
    other question will be storm mode. A couple of tornadoes will be
    possible should a storm remain discrete near the boundary.

    A WW is likely to be considered by 6 PM MDT.

    ..Wendt/Guyer.. 06/08/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!qPC8EhBeQhTa5Fd9ZYdttPq4VwA_EBn6QjMJeNSBBzN3I1jZmHfyigQDiEDJgfpvIEYnOv_S$=
    for graphic product...


    LAT...LON 47830769 48360659 49010489 48990343 48140286 47270338
    46440388 46520418 46160591 46050628 46220758 46670819
    47370816 47830769=20

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