039
AGUS76 KRSA 242113
HMDRSA
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
130 PM PST WED DEC 24 2025
...ONGOING ATMOSPHERIC RIVER SPREADING HEAVY PRECIPITATION ACROSS
SOUTHERN CALIFORNIA AND INLAND TO THE CENTRAL/SOUTHERN SIERRA...
..ANOTHER SYSTEM TO MOVE IN OVERNIGHT TONIGHT AND INTO THE MORNING
BEFORE RIDGING STARTS TO BUILD ON SUNDAY...
METEOROLOGICAL CONDITIONS (SHORT TERM: WED PM - SAT AM)
PRECIPITATION ASSOCIATED WITH THE ATMOSPHERIC RIVER IMPACTING THE
WEST COAST CONTINUES TO SPREAD EASTWARD ACROSS SOUTHERN CALIFORNIA,
FEEDING INLAND TO THE CENTRAL AND SOUTHERN SIERRA.
BIGGEST CHANGE TO THE IMMEDIATE FUTURE (18 TO 00Z) IS ASSOCIATED
WITH INCREASES ACROSS THE SOUTHERN SIERRA, WESTERN SOCAL BIGHT, AND
SAN DIEGO COUNTY AS THE SYSTEM CONTINUES TO PRODUCE IMPRESSIVE RAIN
RATES ON TOP OF EFFICIENT UPSLOPE MOISTURE FLUX. INCREASES OF UP TO
0.75 INCHES WERE MADE TO THE NEXT 6-HOUR WINDOW WITHIN THE
AFOREMENTIONED LOCATIONS.
IN ADDITION TO INCREASES MADE IN THE CURRENT WINDOW, INCREASES WERE
ALSO MADE OVER THE TRANSVERSE RANGE AND SOUTHERN SIERRA AS THE NEXT
PULSE OF AR CONDITIONS MOVES INLAND OVERNIGHT TONIGHT AND INTO
TOMORROW. MODELS CONTINUE TO CONVERGE ON TIMING OF THIS SYSTEM,
PROVIDING MORE CONFIDENCE IN ENHANCED UPSLOPE MOISTURE FLUX ALONG
THE TRANSVERSE RANGE, ALBEIT WEAKER THAN THE CURRENT SYSTEM. SOME
LOCATIONS IN THE HIGHER ELEVATIONS OF SANTA BARBARA, VENTURA, LOS
ANGELES, AND SAN BERNARDINO COUNTIES HAVE INCREASED BY 1.5 TO 2
INCHES THROUGH 12 Z SATURDAY.
METEOROLOGICAL CONDITIONS (LONG TERM: SAT AM - TUE AM)
FORECAST FOR THE EXTENDED REMAINS ON TRACK WITH NO BIG CHANGES FROM
THIS MORNING. AN UPPER TROUGH WILL RESIDE OVER CENTRAL/SOUTHERN CA
EARLY SATURDAY ALLOWING FOR SOME LIGHT LINGERING SCATTERED SHOWERS
ACROSS MUCH OF THE REGION. THE TROUGH WILL PUSH FURTHER INLAND
THROUGHOUT THE DAY AS A SECONDARY LOW DEVELOPS OFF THE BACK EDGE OF
THE TROUGH TO THE SOUTHWEST OF SRN CA BY EARLY SUNDAY. PRECIP WILL
HAVE DIMINISHED BY THEN AS HIGH PRESSURE BUILDS IN BEHIND THE SYSTEM
OVER THE EASTERN PACIFIC AND INTO THE PACNW/NRN CA. DRY CONDITIONS
TO THEN PERSIST THE REST OF THE PERIOD. QPF FOR SATURDAY IS STILL
ANTICIPATED TO BE GENERALLY LESS THAN 0.10".
QPF GRAPHICS ARE AVAILABLE AT WWW.CNRFC.NOAA.GOV/QPF.PHP
CH/AS
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