Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Jun 02 2023 19:38:51

AWUS01 KWNH 021938
FFGMPD
MTZ000-WYZ000-030137-

Mesoscale Precipitation Discussion 0411
NWS Weather Prediction Center College Park MD
338 PM EDT Fri Jun 02 2023

Areas affected...central/eastern Montana

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

Valid 021937Z - 030137Z

Summary...Deepening convection in eastern Montana will migrate
northwestward into areas of very wet ground conditions.  Flash
flood potential is likely to increase through the afternoon and
evening.

Discussion...A broad axis of light to moderate precipitation was
ongoing across portions of the discussion area - generally along
and west of a surface trough/stationary front located from near
Billings to just northwest of Glasgow.  Just east of this trough,
surface heating and warm/moist advection has maintained 500-1500
J/kg MLCAPE and 1-1.3 inch PW values.  Thunderstorms were
deepening within this airmass, with southeasterly
mid-level/steering flow helping to move that convection westward
toward the surface trough.  Additionally, ongoing and prior
rainfall (estimated at 2+ inches in many areas per AHPS) have
moistened soils considerably, and FFG thresholds are quite low
across the region (ranging from 0.25 inch/hr near the surface
trough to around 1 inch/hr along the eastern MT/ND border.)

Models/observations are consistent in depicting a continued
expansion of convective coverage east of the trough along with a
modest increase in precip rates near the trough over the next 4-6
hours.  With low FFGs and wet soils, the risk of flash flooding is
expected to increase through the evening especially 1) near the
surface trough and 2) near any training convection that can
prolong rain fall rates east of the trough.  This risk is expected
to persist through 02Z and beyond - the surface trough and warm
advection regime in eastern Montana is not expected to change
dramatically during the valid MPD timeframe.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-eTzi_BzAtCxRXblt8eAm-M6t-y5gxumJGFOCs4S9Xu7qgeYfaIDqqB6VdeYQjW0BprA=
G_0DcDOley2mXS7M-N9l4eA$  for graphic product...

ATTN...WFO...BYZ...GGW...RIW...TFX...

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

LAT...LON   48990822 48980495 48330407 45990414 45050418=20
            44970867 45260965 46270979 47510958 48480900=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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