Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Jun 03 2023 01:18:29

AWUS01 KWNH 030118
FFGMPD
NDZ000-MTZ000-030715-

Mesoscale Precipitation Discussion 0414
NWS Weather Prediction Center College Park MD
917 PM EDT Fri Jun 02 2023

Areas affected...central/eastern Montana

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

Valid 030115Z - 030715Z

Summary...Flash flood potential continues across the region
through 07Z.

Discussion...Deep convection continues to slowly migrate
northwestward across central and eastern Montana.  Lighter, more
stratiform rainfall continues across central Montana west of a
surface trough/stationary boundary across the region.  A few of
the convective cores have anchored/become stationary east of the
trough, allowing for locally heavy rain rates exceeding 2
inches/hr to materialize.  These rain rates were well above local
FFG thresholds, which are as low as 0.25 inch/hr from near
Lewiston to south of Billings and generally under 1 inch/hr
elsewhere across the state.

The overall synoptic environment supporting ongoing rainfall is
generally unchanged from the prior 3-6 hours.  East of the surface
trough, 500-1000 J/kg MLCAPE supports deep convection, while weak
steering flow aloft supports continued northwestward movement
toward areas of wet/sensitive ground conditions.  Locally heavy
rain rates (exceeding FFG) are expected to continue at times over
the next few hours, although weakening rain rates are expected as
updrafts weaken overnight with nocturnal boundary layer cooling.=20
The current thinking is that despite weakening convection, at
least light to moderate rainfall will occur atop low FFGs tonight,
supporting a continued risk of excessive runoff overnight.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!4mRpNTAyNUAcYEXOT4Scdrq0ruglkof05_ZVSa69ddQDCxatzfIsEp2eMZ31MXgMZpcX=
J_Rjs06brFJw6Yv5oiP3FIM$  for graphic product...

ATTN...WFO...BIS...BYZ...GGW...TFX...

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

LAT...LON   48890608 48780461 48180388 47480417 46680492=20
            45740515 45100580 45040706 45170827 46060858=20
            47530881 48410867 48850772=20

=3D =3D =3D
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