Graphic for MPD #0015

Mesoscale Precipitation Discussion 0015
NWS Weather Prediction Center College Park MD
427 PM EST Sat Jan 13 2024

Areas affected...portions of northern California

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

Valid 132126Z - 140500Z

Summary...Heavy rainfall continues especially across
terrain-favored areas of northwestern California and far
southwestern Oregon.  The heavy rainfall axis will gradually shift
southward and weaken through 00Z.

Discussion...Heavy rainfall persists currently - especially across
portions of the northern California coastal ranges and higher
terrain where 0.3-0.5 inch/hr rainfall rates were noted in the
last hour or so.  Several areas of flooding and excessive runoff
have been reported - especially near Eureka, CA.  The ongoing
heavy rainfall and saturated soils suggests a continued flood risk
of in the near term (through 23Z).

Thereafter, models suggest that the band of heavier rainfall will
gradually shift southward along the California coastline through
04Z as a quickly moving mid-level wave loses amplitude over
Oregon.  As this process occurs, flow aloft (orthogonal to terrain
in the area) will also weaken, resulting in a gradual lessening of
rainfall rates.  Although a few differences in timing is indicated
by model guidance, the general consensus is for rain rates to
lessen below ~0.3 inch/hr beginning at around 01-03Z just as the
axis migrates southward toward Marin County and northern sides of
the San Francisco metro.  The heavy rainfall/flash flood risk is
currently at its peak currently but should begin to lessen after
00Z.  A secondary area of heavy rainfall risk will exist along the
windward side of the Sierra in northeastern California below the
freezing line, although the duration of heavier rain in this area
should be relatively brief.

Cook

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

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

LAT...LON   42382440 42312370 41832205 40982109 39322057
            38912074 39222123 39542151 40032231 39642280
            38482236 37952275 39112401 40792455
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Last Updated: 427 PM EST Sat Jan 13 2024