Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Jun 23 2023 01:59:40

AWUS01 KWNH 230159
FFGMPD
NEZ000-SDZ000-WYZ000-230757-

Mesoscale Precipitation Discussion 0568
NWS Weather Prediction Center College Park MD
958 PM EDT Thu Jun 22 2023

Areas affected...southeastern Wyoming, western Nebraska,
southwestern South Dakota

Concerning...Heavy rainfall...Flash flooding likely

Valid 230157Z - 230757Z

Summary...Flash flood potential continues as slow-moving
thunderstorms continue to produce 1-3 inch/hr rain rates across
parts of the discussion area.

Discussion...Scattered thunderstorms continue across the
discussion area within a couple of regimes: 1) along an
east-to-west oriented confluence band extending from near MHN to
near TOR and 2) along a north-south oriented axis from near ECS
southward to near CYS.  Persistent low-level convergence was
allowing for cells to focus along those two aforementioned axis,
while stationary to slow eastward movement was also noted.  The
slow movement is not surprising given weak (<20 knot) flow through
the low to mid-levels.  Meanwhile, weak easterly low-level
advection was helping to maintain areas of 1000-1500 J/kg MLCAPE
and 1-1.3 inch PW values, continuing to support ongoing heavy
rainfall beneath the more persistent storms.

CAMs and observations suggest that flash flood potential will
continue for the next 3-6 hours.  Storms should exhibit upscale
growth into one or two slowly forward-propagating clusters while
traversing areas of wet soils from prior rainfall.  FFGs across
the region are generally in the 1-1.5 inch/hr range (but increase
dramatically across areas of central Nebraska).  The lower FFG
thresholds should be exceeded periodically this evening as storms
make slow eastward progression across the discussion area.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!8TWKrH-2MJZqbCMP2Y3AxqSBw9ezcC7IAEQM11s2eSZfajpgPxQcVOBYJmd8UgM3gZoi=
DdVWP9KGWt4iXuu81ZGSDpI$  for graphic product...

ATTN...WFO...CYS...LBF...UNR...

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

LAT...LON   44500186 44170126 43240118 42820192 42530261=20
            41720268 41330293 41120446 41910517 43220517=20
            43760517 44240483 44490386 44450283=20

=3D =3D =3D
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