887
FOUS30 KWBC 241126
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
626 AM EST WED DEC 24 2025
DAY 1
VALID 12Z WED DEC 24 2025 - 12Z THU DEC 25 2025
...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
CALIFORNIA...
HIGHLY ANOMALOUS 850-700 MB MOISTURE FLUX ON THE ORDER OF 5+
STANDARD DEVIATIONS ABOVE THE MEAN WILL YIELD EXTREMELY HEAVY
RAINFALL AHEAD OF THE AMPLIFYING MID/UPPER TROUGH LOCATED OFFSHORE
OF THE CALIFORNIA COAST. THE HEAVY RAINFALL TOTALS FOR SOUTHERN CA
WILL LIKELY OCCUR OVER AN 18 HOUR PERIOD, WITH WIDESPREAD 4-7 INCH
TOTALS, WITH ISOLATED MAX AMOUNTS OF 9"+. EXPECT A WELL DEFINED
SOUTH TO NORTH PRECIP BAND IN THIS ANOMALOUS MOISTURE FLUX AXIS
WITH HOURLY RAINFALL RATES OF 0.50-1.5"+ LIKELY. THE POTENTIAL FOR
HIGH HOURLY RAINFALL TOTALS WILL ACCENTUATE RUNOFF OVER SOIL THAT
IS RELATIVELY DRY AND OR OVER RECENT BURN SCAR AREAS. THIS WILL
POSE A SIGNIFICANT THREAT OF FLASH FLOODING, LANDSLIDES, ROCK FALLS
AND MUD SLIDES. THE GREATER THAN NORMAL TRAVEL DURING THE
CHRISTMAS HOLIDAY WILL LIKELY EXPOSE A POTENTIALLY LARGER NUMBER OF
PEOPLE TO THESE LIFT THREATENING HAZARDS AND WAS TAKEN INTO
CONSIDERATION WITH THE UPGRADE TO HIGH RISK.
ALTHOUGH SNOW LEVELS WILL BE LOWERING ACROSS THE SIERRA NEVADA AND
ADJACENT LOCATIONS AND MUCH OF THE HIGHEST ELEVATIONS WILL HAVE
SIGNIFICANT SNOW, SOME OF THE LOWER ELEVATIONS COULD RECEIVE
ADDITIONAL RAINFALL OF 1 TO 4 INCHES. THE SLIGHT RISK AREAS WERE
COMBINED TO COVER HEAVY RAIN TRACKING EASTWARD ACROSS EASTERN
CALIFORNIA, SOUTHERN NEVADA AND INTO SOUTHERN UTAH AND WESTERN
ARIZONA WHERE AREAL AVERAGES UP TO 1 TO 2+ ARE FORECAST.
CAMPBELL
DAY 2
VALID 12Z THU DEC 25 2025 - 12Z FRI DEC 26 2025
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN CALIFORNIA...
A MODERATE RISK REMAINS IN EFFECT FOR A LARGE PORTION OF THE COAST
FROM SAN LUIS OBISPO THROUGH MUCH OF THE TRANSVERSE RANGES NORTH
OF L.A. EXPECT MUCH OF THE HEAVIEST RAIN TO OCCUR ON D2/WEDNESDAY,
BUT BY CHRISTMAS DAY, THERE WILL STILL BE ONE MORE FRONT THAT WILL
CROSS THE AREA FROM WEST TO EAST, WHICH WILL RESULT IN ANOTHER
ROUND OF HEAVY RAINFALL IN SOUTHERN CALIFORNIA. SINCE THIS NEXT
FRONT WILL ARRIVE SOON AFTER THE HEAVIEST RAINS FROM WEDNESDAY,
EXPECT THERE WILL BE OUTSIZED IMPACTS FROM THE HEAVY RAINFALL
ASSOCIATED THEREWITH. SHOWERS AND MAYBE EVEN A FEW THUNDERSTORMS
WILL IMPACT MUCH OF COASTAL SOUTHERN CALIFORNIA AND THE ADJACENT
MOUNTAINS. WHILE EACH ONE WILL BE FAST MOVING, THE RIVERS AND
STREAMS ALL ACROSS SOUTHERN CALIFORNIA WILL LIKELY ALREADY BE
FLOODING, SO ANY ADDITIONAL RAINFALL, ESPECIALLY WHERE HEAVY, WILL
MAKE ONGOING FLOODING WORSE.
CAMPBELL/WEGMAN
DAY 3
VALID 12Z FRI DEC 26 2025 - 12Z SAT DEC 27 2025
...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS SOUTHERN
CALIFORNIA...
THE ATMOSPHERIC RIVER WILL BE WANING HOWEVER GIVEN THE SIGNIFICANT
ACCUMULATIONS LEADING UP TO THIS PERIOD SOILS REMAIN HYPER
SENSITIVE TO ANY ADDITIONAL PRECIPITATION, PARTICULARLY ACROSS THE
TRANSVERSE RANGE AND SURROUNDING LOCATIONS. AS SUCH, A SLIGHT RISK
AREA WAS MAINTAINED FOR THIS PART OF THE STATE ALONG WITH A
MARGINAL RISK THAT EXTENDS UP THE COAST TOWARD SAN FRANCISCO AND
ALONG THE FOOTHILLS OF THE SIERRA NEVADA RANGE.
CAMPBELL
DAY 1 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/94EPOINTS.TXT
DAY 2 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/98EPOINTS.TXT
DAY 3 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/99EPOINTS.TXT
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