Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Nov 06 2023 04:29:24

AWUS01 KWNH 060429
FFGMPD
CAZ000-ORZ000-061000-

Mesoscale Precipitation Discussion 1168
NWS Weather Prediction Center College Park MD
1128 PM EST Sun Nov 05 2023

Areas affected...southwestern Oregon, northwestern California

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

Valid 060427Z - 061000Z

Summary...An approaching mid-level wave over the northeastern
Pacific will interact with moisture and instability across the
discussion area to promote scattered shower and thunderstorm
activity.  Locally heavy rainfall will occur across sensitive
terrain, potentially promoting excessive runoff.

Discussion...Areas of deepening convection were evident via radar
and satellite in a couple of areas - 1) across open Pacific waters
about 45-60 mi west of EKA and 2) near Redding, CA.  The uptick in
convection is indicative of ascent/cooling aloft associated with
the approach of a strong mid-level wave centered near 43.7N,
-132.1W.  Mid-level waves were migrating through southwesterly
flow aloft around the base of this trough and were also likely
contributing to the aforementioned convection.  Meanwhile, cold
mid-level temps (-20C to -25C at 500mb) and 50s F dewpoints near
the coast were contributing to modest buoyancy along the coast.
Instability profiles, orographic lift (with southwesterly flow
against terrain across the discussion area), and the approach of
the mid-level wave will all contribute to a gradual increase in
and eastward development of shower and thunderstorm activity
through 10Z and likely beyond.

As these showers/thunderstorm develop inland, areas of 0.25-0.5
inch/hr rain rates (locally higher) should materialize for brief
periods.  Fast flow aloft should allow for these rain rates to
stay brief except for instances where convection can repeat over
any local area. Furthermore, these rain rates should occur over
burn scars across the discussion area, enhancing local runoff (and
flash flood) potential.  Isolated/localized flash flooding is
possible as precipitaion increases across across the discussion
area through at least 10Z.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-OMdEdrW8mTjgqi9WMF6owjVdXlbnlbaJcP64hUnkEqRIrZfscVkgbvOm8qKzNRamOEG=
pIv1a63OYCBQ_Au1OVNrwoc$  for graphic product...

ATTN...WFO...EKA...MFR...PQR...

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

LAT...LON   44242369 43682239 42382202 41422237 40612332=20
            40882438 42602475 44082432=20

=3D =3D =3D
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