Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Mar 15 2023 08:58:11

AWUS01 KWNH 150858
FFGMPD
CAZ000-151500-

Mesoscale Precipitation Discussion 0109
NWS Weather Prediction Center College Park MD
457 AM EDT Wed Mar 15 2023

Areas affected...Southern California

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

Valid 150900Z - 151500Z

Summary...Another 0.5-2 inches of rainfall is expected across the
discussion area, resulting in localized hydrological impacts and
excessive runoff.

Discussion...An ongoing atmospheric river is affecting the
discussion area currently, with a recent resurgence of moderate to
heavy rainfall across the coastal ranges of southern California
and vicinity over the past 2-3 hours.  Rainfall rates in most
areas are limited to around 0.2-0.5 inch/hr, with heavier rain
rates focused along terrain favored areas at times.  The rainfall
appears to be tied to the approach of mid-level shortwaves
embedded within the atmospheric river (particularly one indicated
by satellite and objective analyses near 34N 120W).  Moistening
atmospheric conditions (PW values increasing to 1.3-1.5 inch) and
strengthening low-level wind fields orthogonally oriented to
coastal ranges were also noted.

There is a conditional risk for heavier rainfall to materialize
through 15Z or so as slightly more buoyancy located offshore (500
J/kg MUCAPE) approaches coastal areas.  The instability could
allow for slightly heavier rainfall rates and attendant flash
flood risk should the deeper convection materialize.  Otherwise,
the ongoing atmospheric river event should wane after 15Z as
heavier precipitation dissipates and moves east of the discussion
area.  Areas of 0.5-2 inch totals are expected to cause localized
impacts especially in sensitive, terrain-favored areas.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5ii6p7cLwFSPF-wu8ydW0_WNZiI3gzOIbiXLcI1OPolKnZHbWwj4xYUxRI-qu2TWZ4lj=
oWASuiJoLGIz6UAXZv5QxeA$  for graphic product...

ATTN...WFO...HNX...LOX...PSR...SGX...VEF...

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

LAT...LON   35341976 35251847 34661702 33841629 33051605=20
            32631623 32511678 32741724 33261772 33641826=20
            34071902 34422009 34542036 34992030=20

=3D =3D =3D
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