Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Aug 04 2023 20:16:39

AWUS01 KWNH 042016
FFGMPD
ORZ000-050115-

Mesoscale Precipitation Discussion 0862
NWS Weather Prediction Center College Park MD
415 PM EDT Fri Aug 04 2023

Areas affected...South-central Oregon...

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

Valid 042015Z - 050115Z

SUMMARY...Slow moving thunderstorms capable of 1-1.5" totals over
barren soils entering deeper moisture environment pose isolated
localized flash flooding risk through evening.

DISCUSSION...GOES-W Visible imagery depicts a broad status shield
across north-central to northwest Oregon associated with deeper
layer anomalous moisture values.  Along the southern periphery of
this mid-level shear axis, full sun and proximity to this
anomalous moisture pool has resulted in solid insolation and
slowly increasing unstable environment...resulting in up to 1000+
J/kg MLCAPE.  A strong 90kt+ westerly jet crossing central CA with
modest anticyclonic ridging up toward northern CA increasing
divergence aloft and supporting slightly stronger than normal
naturally occurring deep layer cyclone, as such, accelerating
800-600 mb layer flow out from the northeast of Oregon becoming
confluent across south-central OR into the eastern slopes of the
Oregon Cascades resulting in moisture advection into the area of
highest instability. GPS network shows slow but steady rise of
total PWats toward the .75" range with some slightly higher values
nearing 1" into SE Oregon.

Perpendicular convergence into the terrain has sparked widely
scattered thunderstorms across W Klamath into Lake county.  Deep
layer steering is weak within the col between both the shear axis
to the northeast and cyclone to the south but is generally
northerly.  Strengthening 850-700mb flow up to 15kts locally
should support eastward propagation, but with 5-10kts should allow
for some increased duration.  Rainfall rates have initially
started to reach .5-.7"/hr; but as the cluster develops/expands
and shifts into deeper moisture, hourly rates of 1-1.25"/hr are
likely probable.  This may result in localized spots of 1-1.5"+
totals and given dry/rocky terrain and FFG values below these
values widely scattered spots of flash flooding are considered
possible through the evening hours.=20=20

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!40QlA7WWw13plxK3WSdzRer8VVMkgXjgVK9IRXRtcEqTRMe8oKTDwScapZkTp1sxxC4E=
TNt3QuHsVG8Z07Zpv2g1VRY$  for graphic product...

ATTN...WFO...BOI...MFR...PDT...PQR...

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

LAT...LON   44292053 43861911 43241775 42631741 42081778=20
            42051945 42052000 42052067 42122222 42412259=20
            43452264 44222195=20

=3D =3D =3D
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