• MESO: Mesoscale Discussion 1587

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Aug 24 08:00:55 2021
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    ACUS11 KWNS 240800
    SPC MCD 240800=20

    Mesoscale Discussion 1587
    NWS Storm Prediction Center Norman OK
    0300 AM CDT Tue Aug 24 2021

    Areas affected...Portions of western/central MN into far
    west-central WI

    Concerning...01Z Outlook upgrade=20

    Valid 240800Z - 241000Z

    SUMMARY...The 01Z Day 1 Convective Outlook has been effectively
    upgraded to a Slight Risk through 12Z this morning across recently
    issued Severe Thunderstorm Watch 460. Scattered damaging wind gusts
    up to 70 mph should be the main threat with a line of storms moving

    DISCUSSION...An organized MCS with a history of producing sporadic
    severe wind gusts across eastern ND/SD will continue to move
    eastward over parts of western/central MN this morning. A surface
    front and corresponding instability gradient is generally draped
    east to west across this region. Rich low-level moisture and steep
    mid-level lapse rates are supporting substantial MUCAPE (2000-3000+
    J/kg) along and south of the front. 30-40 kt of deep-layer shear
    will likely prove sufficient for continued organization of this MCS
    through the early morning hours, with some evidence of a rear-inflow
    jet present per recent velocity data from KABR. The northern portion
    of the line may tend to stay on the cool side of the surface front,
    but the southern portion along/south of the boundary may have a
    tendency to strengthen over the next few hours as the line develops east-southeastward along the instability gradient. Given the large
    reservoir of buoyancy already available, and continued low-level
    warm advection which may further destabilize the environment ahead
    of the line across central MN, there should be an increased
    potential for mainly scattered severe/damaging downdraft wind gusts
    up to 70 mph as the southern flank of the MCS strengthens.
    Occasional large hail may also occur with discrete storms developing
    across southern/central MN in the low-level warm advection regime.
    The past several HRRR runs have been consistent in depicting this
    scenario. Severe Thunderstorm Watch 460 has recently be issued to
    address this threat, and the 01Z Day 1 Convective Outlook has
    effectively been upgraded to a Slight Risk through 12Z for the
    counties within the watch.

    ..Gleason/Thompson.. 08/24/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!qh48O8d0kbJ7EHEtZB7_WnBB2s_NdGHE-O9l-t116QmO08976SVYwdam1LuAVOxRiZd5zT9S$=
    for graphic product...


    LAT...LON 44119518 44259563 44499601 44639645 45619686 46639678
    46639678 46689618 46629552 46369455 46159308 45699214
    44569214 44199255 44139396 44089455 44109498 44119518=20

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