Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Jun 09 2023 17:49:47

AWUS01 KWNH 091749
FFGMPD
IDZ000-NVZ000-CAZ000-ORZ000-092345-

Mesoscale Precipitation Discussion 0450
NWS Weather Prediction Center College Park MD
149 PM EDT Fri Jun 09 2023

Areas affected...Northern NV...Eastern OR...Southwest ID

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

Valid 091750Z - 092345Z

SUMMARY...Potent thunderstorms containing rainfall rates up to
1"/hr may lead to flash flooding in areas with sensitive soils and
poor drainage areas.

DISCUSSION...A large upper low continues to spin over the
Northwest with a vigorous lobe of vorticity at 700mb working its
way through southeast OR. Visible satellite showed a large field
of growing cumulonimbus clouds over northern NV and southern ID as
a result of strong surface based heating. In eastern OR, a more
dense overcast cloud deck is limiting surfaced based heating, but
this area also coincides within the most anomalous source of
moisture aloft. PWs in the area look to range between 0.75-1.0",
which resides between the 90-97.5th climatological percentile
according to NAEFS. Area averaged HRRR soundings in eastern OR
contained low-mid level RH values as high as 85% and the available
CAPE present in a classic "skinny" type profile. MLCAPE will range
between 250-500 J/kg across the highlighted region by mid
afternoon. RH values are not quite as high in ID, but the
atmosphere will be more unstable and features a greater
concentration of sensitive soils given recent rainfall over the
past 7 days (AHPS shows 400-600% of normal rainfall from northeast
NV on north towards Boise and the Bitterroots).

With lapse rates steepen over ID and northern NV in the higher
terrain, numerous thunderstorms will develop this afternoon. There
will also be scattered storms forming in southern OR as surface
based heating continues in lee of the Cascades. Steering winds
will push developing storms from east of the Cascades into
southeast OR, while storms track south-to-north from northern NV
into southern ID. The aforementioned combination of instability
and moisture content over sensitive soils lays the groundwork for
a flash flood threat this afternoon. The 12Z HREF shows 50-80%
probabilities of 3-hr QPF > 3-hr FFGs in eastern OR and 20-30%
chances in northern NV/southern ID this afternoon. Locations most
prone to flash flooding are spots that have been hit hardest by
recent rainfall over the past week, in poor drainage areas, and
within more heavily urbanized communities.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7vK-svyQvsbAFh1gjkKSHgoxssKaP-O0N0DC82u8_CV-MYHLfhSMw8_F9L4QVQ1XqmN_=
xTkEp567LL0FvSZ2fjsBU50$  for graphic product...

ATTN...WFO...BOI...LKN...MFR...PDT...PIH...REV...

ATTN...RFC...CBRFC...CNRFC...NWRFC...NWC...

LAT...LON   45371696 44551543 44031461 43031407 42161397=20
            41291501 41101589 41261633 41661719 41191878=20
            41341986 42072069 43162087 44282005 45281866=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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