Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Sep 10 2025 21:05:13

AWUS01 KWNH 102105
FFGMPD
CAZ000-110300-

Mesoscale Precipitation Discussion 1070
NWS Weather Prediction Center College Park MD
504 PM EDT Wed Sep 10 2025

Areas affected...Northern California

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

Valid 102100Z - 110300Z

SUMMARY...Widely scattered slow-moving showers and thunderstorms
across northern California are likely to contain maximum rainfall
rates up to 1"/hr and may overlap with sensitive burn scar
locations. Leading to the potential for isolated flash flooding
through this evening.

DISCUSSION...GOES-West ML-WV imagery depicts and vertically
stacked mid-upper level low over northern California this
afternoon, which has led to sufficient lapse rates up to 8C/km and
blossoming thunderstorms coverage. Mean layer winds underneath
this low are very weak or nonexistent, which has anchored most of
the heavy rainfall to the Klamath and Siskiyou Mts of northern CA.
These slow-moving storms and buoyant atmosphere may help rainfall
rates peak up to 1"/hr, but with most cells likely exhibiting
rates around 0.5"/hr.

These rainfall rates are enough to cause concerns over recent burn
scars that are most susceptible to rapid runoff. It is within
these locations where isolated to scattered flash flooding is most
possible through this evening until daytime heating diminishes and
lapse rates lessen. However, isolated flash flooding is also
possible elsewhere should thunderstorms containing 1"/hr rates
maintain and remain stalled over an area for a few hours.

Snell

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!47EWxXAU9ANuy96zr7gZZA9t8PU82v5iwhMSGIsRZw4F_IRmetrGPA1EWB5dGkqHIDNF=
EU2YG37LswkWg2hJpPlSg4k$  for graphic product...

ATTN...WFO...EKA...MFR...MTR...STO...

ATTN...RFC...RSA...NWC...

LAT...LON   41872178 41652145 41112139 40482137 40042144=20
            40042187 40482215 40382246 40022256 39542248=20
            38812228 38652268 39062311 40032354 40902358=20
            41432323 41802251=20

=3D =3D =3D
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