Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Jun 11 2023 17:41:31

AWUS01 KWNH 111741
FFGMPD
MTZ000-WYZ000-IDZ000-112345-

Mesoscale Precipitation Discussion 0462
NWS Weather Prediction Center College Park MD
140 PM EDT Sun Jun 11 2023

Areas affected...Northern Rockies

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

Valid 111745Z - 112345Z

SUMMARY...Potent thunderstorms containing heavy rainfall may lead
to areas of flash flooding with overly saturated soils most at
risk.

DISCUSSION...A seemingly endless stretch of stormy weather, which
for some areas has now lasted 2-3 weeks, sticks around for another
day as the region remains positioned to the north of a cut-off low
in the Southwest. PWATs will remain in the 0.8-1.0" range, which
are above the 90th climatological percentile. Compared to
yesterday, there is less cloud debris and thus stronger surface
based heating unfolding. RAP mesoanalysis already shows 250-500
J/kg of MLCAPE present, with most of this MLCAPE having manifested
itself in just the past 3-hours. RAP forecasts indicate MLCAPE
should surpass 500 J/kg this afternoon, which combined with the
residing moisture content aloft could support hourly rainfall
rates up to 1"/hr.

The region features overly saturated soils from the rounds of
storms day after day for at minimum a couple of weeks. AHPS 7-14
day rainfal totals have ranged between 400-600% of normal from
southeast OR and southern ID into the Bitterroots and western MT.
The 12Z HREF contained probabilities as high as 40-50% for 1-hr
QPF > 1-hr FFGs in most areas, but central ID stood out featuring
the higher side of those probabilities this afternoon. Mean storm
motions will remain quite slow (generally topping around 5 knots).
While these storms will remain pulse-like primarily, the heavy
rainfall rates combined with the overly saturated soil keeps a
slight chance for highly localized flash flooding into the
afternoon hours. The overly saturated soils, as well as along
complex terrain, within burn scars, and poor drainage spots are
most at-risk to potential flash flooding.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!8TaJva-4oPQxTAR8O4r_hHyUwVpg39eAaY1txtbTBXgkCZ2mgyiSWAhCHt71heyfsE3L=
VPsE-sB6EZreQj9-1H02DoU$  for graphic product...

ATTN...WFO...BOI...BYZ...MSO...PIH...RIW...TFX...

ATTN...RFC...CBRFC...MBRFC...NWRFC...NWC...

LAT...LON   48111351 47141233 46291150 45721063 45580987=20
            45240933 44110881 42820922 42681155 44151193=20
            43871324 43551388 43551501 43731580 44291620=20
            44681661 45131667 45581631 45981583 46311529=20
            46871481 47511429=20

=3D =3D =3D
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