Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Thu Jun 22 2023 03:41:18

AWUS01 KWNH 220341
FFGMPD
NEZ000-SDZ000-NDZ000-220939-

Mesoscale Precipitation Discussion 0557
NWS Weather Prediction Center College Park MD
1140 PM EDT Wed Jun 21 2023

Areas affected...northwestern Nebraska, western South Dakota,
central North Dakota

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

Valid 220339Z - 220939Z

Summary...Slow-moving convection continues along and just east of
a nearly stationary surface boundary.  Areas of flash flooding are
possible through 09Z.

Discussion...Convective cells have materialized along and just
east of a stationary boundary over western portions of the
discussion area over the past 1-2 hours.  The storms are also
located just east of stronger mid-level flow aloft (centered over
Wyoming and eastern Montana), allowing for slow storm motions
ranging from 10-15 knots over western South Dakota and nearly
stationary across northwestern Nebraska near CDR.  The airmass
supporting the storms is plenty buoyant (1000+ J/kg MLCAPE) and
moist (1.5 inch PW), allowing for efficient rainfall processes to
occur beneath the storms.  Though cellular convection remains the
primary storm mode, localized backbuilding and slow movement was
allowing for spots of 1-2 inch/hr rain rates to develop, which are
challenging local FFG thresholds that range from 1-2 inches/hr in
some areas.

Over time, continued forcing for ascent near the surface boundary
will allow for increasing convective coverage especially from
western South Dakota into central North Dakota from 05Z onward.=20
With cells focused mainly along the front while remaining oriented
parallel to flow aloft, training of storms should continue to
produce 1-2 inch/hr rain rates, with an expected 1-3 inches of
rainfall along a general axis from west of PHP northeastward to
D07 to to near BIS and potentially DVL.  Flash flooding is
possible in this scenario.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5vu5EEe4VwRWdFUdKatXEI4aYn2snGVHVGpq1aDpyZ8vE6AN2_ZbGzvUHJOQz62vGOLH=
YYUF4DSKltGL0P7fy-whcVc$  for graphic product...

ATTN...WFO...ABR...BIS...CYS...FGF...LBF...UNR...

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

LAT...LON   49029882 48659812 47489844 44660046 42680266=20
            42430330 42740342 43870340 45590273 47930140=20
            48870006=20

=3D =3D =3D
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