• Heavy Rain/Flooding ND/MN

    From Mike Powell@618:250/1 to All on Thu Aug 29 10:00:00 2024
    AWUS01 KWNH 291202
    FFGMPD
    MNZ000-NDZ000-291700-

    Mesoscale Precipitation Discussion 0943
    NWS Weather Prediction Center College Park MD
    800 AM EDT Thu Aug 29 2024

    Areas affected...Eastern ND...Northwest MN

    Concerning...Heavy rainfall...Flash flooding possible

    Valid 291200Z - 291700Z

    SUMMARY...Additional areas of heavy showers and thunderstorms can
    be expected going through the morning hours across portions of
    eastern ND and northwest MN. Localized training of these storms
    may still pose some additional isolated flash flooding concerns.

    DISCUSSION...The early morning GOES-E IR satellite imagery shows a well-organized axis of convection with locally very heavy rainfall
    impacting portions of eastern ND and northwest MN. The convection
    is embedded within a highly divergent flow pattern aloft downwind
    of a deep upper trough/closed low over the far northern High
    Plains and adjacent areas of south-central Canada.

    This coupled with strong warm air advection ahead of a frontal
    occlusion and with a well-defined axis/pool of moderate to strong
    elevated instability focusing along and north of a warm front
    lifting through the Upper Midwest has been helping to drive a
    persistence of the convection over the last few hours.

    A southwest low-level jet of 40 to 50 kts is still in place nosing
    up across the Red River Valley of the North which is yielding
    strong moisture transport/convergence and there is a corridor of
    MUCAPE values of 2000 to 3000 J/kg still noted over eastern ND and
    far western MN. These ingredients are likely to persist going
    through the morning hours, with perhaps some subtle decrease in
    the low-level jet. However, given the current orientation of the
    convection being parallel to the low-level jet and with enhanced moisture/instability transport, there will be concerns lingering
    this morning for persistent bands of convection that will be
    capable of locally training over the same area.

    A large number of the 00Z/06Z HREF members tend to suggest a rapid
    weakening of the activity by mid to late morning, but this is not
    the case with recent HRRR guidance which suggests a persistence,
    especially across northwest MN, of convection that may result in
    an additional 3 to 4 inches of rain locally. Satellite trends over
    the last 1 to 2 hours would support the HRRR guidance, and
    especially with the array of deep cold convective tops seen over
    the region.

    There may be some additional isolated flash flooding concerns this
    morning as this ongoing axis of convection over eastern ND through
    northwest MN persists.

    Orrison

    ATTN...WFO...BIS...DLH...FGF...

    ATTN...RFC...MBRFC...NCRFC...NWC...

    LAT...LON 48959479 48609374 48139396 47719475 47059699
    46689816 46999871 47949776 48819633
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