150
AWUS01 KWNH 261035
FFGMPD
CAZ000-262000-
MESOSCALE PRECIPITATION DISCUSSION 1280
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
535 AM EST FRI DEC 26 2025
AREAS AFFECTED...TRANSVERSE RANGES TO SOUTHERN CA COAST
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 261034Z - 262000Z
SUMMARY...AREAS OF FLASH FLOODING WILL CONTINUE TO AFFECT PORTIONS
OF THE TRANSVERSE RANGES TO THE COAST OVERNIGHT INTO THE LATE
MORNING HOURS. HOURLY RAINFALL VALUES OF 0.5 TO 1.0 INCHES
(LOCALLY HIGHER) ARE LIKELY WHICH WILL MAINTAIN CONCERNS FOR
IMPACTS INCLUDING LANDSLIDES/DEBRIS FLOWS AND URBAN FLOODING.
DISCUSSION...1015Z RADAR IMAGERY COMBINED WITH LOCAL MESONET AND
PERSONAL WEATHER OBSERVATIONS OUT OF SOUTHERN CA CONTINUED TO SHOW
AREAS OF HEAVY RAIN WITHIN A NARROW AXIS FROM THE OFFSHORE WATERS
INTO MAINLY VENTURA COUNTY. HOURLY RAINFALL OVER 1 INCH HAS BEEN
OBSERVED IN VENTURA COUNTY WITH 3-HOUR TOTALS OF 1 TO 2+ INCHES.
LOCAL WUNDERGROUND GAUGES SHOWED A COUPLE OF 30 MINUTE RAINFALL
VALUES OVER 0.5 INCHES WITHIN THE PAST 2-3 HOURS NEAR OJAI. THESE
RAINS WERE ASSOCIATED WITH A SLOW MOVING LOW LEVEL CONVERGENCE
AXIS (REMNANT FRONTAL BOUNDARY) THAT WAS ORIENTED SSW TO NNE
ACROSS VENTURA COUNTY WITH PW VALUES OF 1.0 TO 1.2 INCHES ALONG
THE COAST AND SSW 850-700 MB WINDS OF 25-35 KT. ENHANCED
DIVERGENCE ALOFT MAY ALSO BE CONTRIBUTING TO INCREASED RAINFALL
INTENSITY OVER THE REGION, WITHIN THE RIGHT-ENTRANCE REGION OF A
150 KT JET STREAK ALOFT LOCATED OVER THE SIERRA NEVADA.
SHORT TERM FORECASTS FROM THE RAP SHOW THE LOW LEVEL CONVERGENCE
AXIS AND LOCALIZED MAX IN IVT VALUES (UP TO 500 KG/M/S) SLOWLY
ADVANCING EASTWARD OVER THE NEXT 6-9 HOURS. THE RESULT WILL BE
LOCALIZED HIGH RAIN RATES INTO THE TERRAIN, SLOWLY SHIFTING EAST,
GIVEN THE FAVORABLE ORTHOGONAL ORIENTATION OF THE LOW LEVEL WINDS
TO THE AXIS OF TERRAIN. HOURLY RAINFALL OF 0.5 TO 1.0+ INCHES
SHOULD ADVANCE EASTWARD FROM VENTURA COUNTY INTO LOS ANGELES
COUNTY THROUGH 15Z, POSSIBLY CLEARING LOS ANGELES COUNTY AFTER
ROUGHLY 17Z. WHILE THE GREATEST POTENTIAL FOR THESE HIGHER RATES
WILL BE IN THE UPSLOPE FAVORED TERRAIN, SHALLOW/WEAK INSTABILITY
UP TO ~250 J/KG AND SHORT TERM TRAINING COULD SUPPORT 0.5+ INCH
HOURLY RAINFALL INTO THE LOWER ELEVATION URBAN AREAS AS WELL.
ADDITIONAL RAINFALL OF 1 TO 3 INCHES WILL BE POSSIBLE THROUGH 20Z
WITH POTENTIAL FOR HIGHER IMPACT LOCALIZED FLASH FLOODING OVER
SENSITIVE BURN SCAR LOCATIONS IN AND AROUND THE LOS ANGELES METRO.
GIVEN HEAVY RAIN OVER THE PAST 2 DAYS, MANY LOCATIONS CONTAIN
SATURATED SOILS WITH ADDITIONAL RAINFALL LIKELY TRANSLATING
DIRECTLY INTO RUNOFF. WITH THIS RAINFALL, THERE WILL BE THE
POTENTIAL FOR DANGEROUS TRAVEL AND LIFE-THREATENING IMPACTS FROM
FLOODING.
OTTO
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...HNX...LOX...SGX...
ATTN...RFC...RSA...NWC...
LAT...LON 34811863 34471778 34201694 33671672 33361764
33471824 33761916 34071955 34451952 34761922
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