Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Jun 16 2023 00:48:02

AWUS01 KWNH 160047
FFGMPD
SDZ000-NDZ000-160642-

Mesoscale Precipitation Discussion 0494
NWS Weather Prediction Center College Park MD
847 PM EDT Thu Jun 15 2023

Areas affected...portions of the Dakotas

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

Valid 160042Z - 160642Z

Summary...Convective coverage should continue to increase over the
next several hours.  Slow storm movement will contribute to the
heavy rainfall and flash flood risk.

Discussion...A recent uptick in convective coverage has been noted
across central South Dakota.  Storms have also persisted across
central North Dakota for much of the afternoon on an isolated
basis.  The storms are benefiting from low-level convergence
associated with a very slow-moving surface boundary extending from
near BIS to near PIR, with the airmass along of that boundary
remaining moderately unstable (1000-1500 J/kg MLCAPE) and moist
(1.4 inch PW values).  The approach of a mid-level shortwave
trough from western South Dakota was also contributing to ascent
and increasing convective coverage.  Steering flow aloft was weak,
but southerly, allowing for convection currently developing along
the surface boundary to drift north and potentially repeat or
train across local areas.=20

Models/CAMs suggest that thunderstorms should persist along the
surface boundary through the night, which appears plausible as the
overall synoptic scenario forcing convection will not change much
through 06Z.  Instability values are expected to support
convective development through the overnight hours despite modest
boundary layer cooling.  Areas of 1-2 inch/hr rain rates are
expected beneath the slowest-moving and training cells, which
should challenge local FFG thresholds across the area (currently
in the 1.5-2.5 inch/hr range.  Spotty/localized flash flooding is
possible in this regime.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!8T7MDxYsXBJ-Be8uRHE5OwpZwuB0UtPRK00DZpe5xxTcUoNUuUucItpjU5MZesl-5-Iw=
2ngmImMrJHa6FpSK9SFQLcM$  for graphic product...

ATTN...WFO...ABR...BIS...FGF...FSD...UNR...

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

LAT...LON   49000014 48719924 46699862 44999843 43399825=20
            43009960 43220131 45880166 48270138 48880118=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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