Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Dec 09 2022 23:35:29

AWUS01 KWNH 092335
FFGMPD
CAZ000-ORZ000-101133-

Mesoscale Precipitation Discussion 1147
NWS Weather Prediction Center College Park MD
635 PM EST Fri Dec 09 2022

Areas affected...Southwest OR & Northwest CA

Concerning...Heavy rainfall

Valid 092333Z - 101133Z

Summary...Increasing low-level inflow and low-level frontogenesis
should lead to 0.5"+ hourly rain totals with local amounts of 3-4"
through 12z.  This could lead to issues in area burn scars.

Discussion...Water vapor satellite imagery reveals a strong upper
level shortwave about 500 miles offshore the OR/CA border moving
towards the region.  Precipitable water values of 0.75" are
pushing inland ahead of this feature per GPS data.  Instability is
virtually nil, but inflow at 850 hPa is SSW at ~40 kts per the
KBHX VAD wind profile.

The expectation is for the 850 hPa inflow to increase towards 70
kts and veer slightly, which when combined with the available
moisture and low-level frontogenesis slowly edging inland, should
yield hourly rain totals of 0.5"+, which has been indicated by the
18z HREF as beginning after 02z across portions of southwest OR,
and should shift down the coast of northwest CA with time.  The
guidance indicates local 3-4" of rain through 12z, which seems
reasonable given the rates expected.  Freezing levels are quite
low, so any heavy rain related issues would be at lower elevation,
generally under 5000 feet.  The expected heavy rains would be
problematic should it impact any area burn scars.

Roth

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5YsGXqqa_m2vCwCaCP8kJVEfKum_p4Ou4W8t-Y901Jg5xifF4kjED7nmlMr7Rnuusda-=
CluJPIkj6-uKeo7my9ajhO4$  for graphic product...

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

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

LAT...LON   43022389 41382369 40152344 39872356 39612389=20
            39902422 40392453 41142429 41822435 42892466=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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