Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon May 29 2023 18:40:23

AWUS01 KWNH 291840
FFGMPD
SDZ000-NDZ000-MTZ000-300038-

Mesoscale Precipitation Discussion 0377
NWS Weather Prediction Center College Park MD
239 PM EDT Mon May 29 2023

Areas affected...North Dakota and far eastern Montana

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

Valid 291838Z - 300038Z

Summary...Scattered, slow-moving showers and thunderstorms could
pose a localized, isolated risk of flash flooding today.

Discussion...Areas of convection have deepened over the past hour
or so across eastern Montana and western North Dakota.  The storms
are responding to weak ascent from mid-level shortwave troughs
aloft over the region, insolation/surface-based destabilization
(2000 J/kg SBCAPE), and convergence along a weak/subtle surface
trough across eastern Montana from near OLF to near MLS.  Point
forecast soundings indicate very weak westerly wind fields aloft
through the troposphere, suggesting that current cells will
exhibit slow storm motions.  A few of the cells have also
clustered and oriented in such a way that spots of 1-1.5 inch/hr
rain rates have been observed especially in northeastern Montana
near OLF.  These rain rates, although sparse in coverage, were
approaching or locally exceeding 1-1.5 inch/hr FFG thresholds
across much of the region.

Models/CAMs and observations support eastward progression of
thunderstorm activity through 00Z.  The speed of movement will be
slow (generally less than 20 knots), although perhaps speeds could
be locally augmented by any upscale growth of cells into
propagating clusters/lines.  Again, the slow storm motions and
potential areas of training/repeating could lead to isolated
instances of flash flooding.  Convection is expected to gradually
reach portions of central North Dakota today - generally after
22Z.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_oRSZIrr74Y468gQ0TPlExR8Xlu1usoR40JbcbKLKG2Z0Ohi4ZVUT5NVykDQja4h9c1e=
PJHiPuQsLQZ-ljmjkQw5eNY$  for graphic product...

ATTN...WFO...ABR...BIS...BYZ...FGF...GGW...UNR...

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

LAT...LON   49120124 48780006 47529964 46179982 45770219=20
            46000463 47010563 48860582 49110502=20

=3D =3D =3D
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