672
FXUS66 KSGX 232130
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
130 PM PST TUE DEC 23 2025
SYNOPSIS
WIDESPREAD HEAVY RAIN IS EXPECTED LATE THIS EVENING INTO WEDNESDAY
ACROSS SOUTHERN CALIFORNIA. AFTER THE INITIAL RAIN BAND MOVES FROM
NORTHWEST TO SOUTHEAST ACROSS THE AREA ON WEDNESDAY, SCATTERED
LOCALLY HEAVY RAIN IS EXPECTED TO CONTINUE ACROSS MUCH OF THE AREA
INTO CHRISTMAS DAY. SNOW LEVELS WILL REMAIN HIGH THROUGH THE
DURATION OF THE EVENT INCREASING THE FLOOD THREAT FOR THE MOUNTAINS,
PARTICULARLY IN SAN BERNARDINO COUNTY. IN ADDITION TO WIDESPREAD
HEAVY RAIN ON WEDNESDAY, GUSTY SOUTHERLY WINDS ARE EXPECTED FOR THE
COAST, VALLEYS, SAN BERNARDINO MOUNTAINS, AND HIGH DESERT. ANOTHER
ROUND OF MORE WIDESPREAD MODERATE TO HEAVY RAIN IS EXPECTED SOMETIME
LATE EVENING ON THURSDAY INTO FRIDAY MORNING. DRIER CONDITIONS ARE
LOOKING MORE LIKELY FOR SOMETIME SATURDAY AND SUNDAY. WE'RE
MONITORING THE POTENTIAL FOR ADDITIONAL PRECIPITATION AROUND NEW
YEAR BUT THERE IS STILL CONSIDERABLE UNCERTAINTY IN THE FORECAST.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
KEY POINTS:
* WIDESPREAD MODERATE TO HEAVY RAINFALL CHRISTMAS EVE WITH THE
POTENTIAL FOR ROADWAY FLOODING AND LOCALIZED FLASH FLOODING FROM
THE COAST TO DESERTS. RAPID RISES IN SMALL STREAMS AND INCREASED
FLOW IN MAIN STEM RIVERS EXPECTED.
* THE HIGHEST RISK FOR FLASH FLOODING ON CHRISTMAS EVE IS FOR THE
SAN BERNARDINO COUNTY MOUNTAINS WITH A HIGH RISK FOR EXCESSIVE
RAINFALL THAT COULD RESULT IN DAMAGING AND POTENTIALLY LIFE-
THREATENING FLASH FLOODING, MUD SLIDES, AND DEBRIS FLOW. THE
THREAT WILL BE HIGHEST DURING THE DAY ON WEDNESDAY.
* GUSTY SOUTH WINDS WILL DEVELOP TONIGHT AND CONTINUE THROUGH
WEDNESDAY EVENING WITH GUSTS 30 TO 40 MPH, LOCALLY UP TO 45 MPH
NEAR THE COAST AND TO 55 TO 75 MPH ALONG AND BELOW THE DESERT
SLOPES OF THE SAN BERNARDINO COUNTY MOUNTAINS. MAKE SURE TO
SECURE OUTDOOR FURNITURE. TREE DAMAGE IS POSSIBLE.
* SCATTERED SHOWERS WILL CONTINUE ON CHRISTMAS DAY WITH ANOTHER
ROUND OF MORE WIDESPREAD SHOWERS FOR THURSDAY NIGHT INTO FRIDAY.
SNOW LEVELS WILL LOWER TO AROUND 7000 FEET FOR THURSDAY INTO
THURSDAY EVENING, THEN LOWER TO AROUND 6000 FEET BY LATE FRIDAY
CREATING SLICK CONDITIONS ON MOUNTAIN HIGHWAYS ABOVE 6000 FEET.
AN ATMOSPHERIC RIVER IS STILL ON TRACK TO IMPACT SOUTHERN CALIFORNIA
ON WEDNESDAY. AT 1 PM, AREAS OF LIGHT RAIN ARE STREAMING ACROSS MUCH
OF THE AREA, INCLUDING PORTIONS OF THE DESERTS. SO FAR ONLY MINIMAL
AMOUNTS HAD ACCUMULATED WITH MOST PLACES LESS THAN 0.10" INCH OVER
THE LAST 6 HOURS. AS WE GET INTO TONIGHT LOCALLY HEAVY RAIN MAY
DEVELOP, MOST LIKELY ON THE COASTAL SLOPES OF THE SAN BERNARDINO
COUNTY MOUNTAINS. THE HEAVIEST AND MOST WIDESPREAD RAIN IS EXPECTED
THROUGH THE DAY WEDNESDAY, WITH THE HEAVY RAIN MOVING NORTHWEST TO
SOUTHEAST FROM ORANGE COUNTY TO SAN DIEGO COUNTY DESERTS. AFTER THE
RAIN BAND PASSES, SCATTERED SHOWERS ARE EXPECTED TO CONTINUE WITH
LOCALLY HEAVY RAIN INTO THURSDAY (CHRISTMAS DAY). LATEST GUIDANCE
SHOWS A SIGNIFICANT DECREASE IN IVT (ATMOSPHERIC MOISTURE) DURING
THE DAY THURSDAY, BRINGING THE POTENTIAL FOR PERIODS NO
PRECIPITATION FOR SOME AREAS. SNOW LEVELS ARE EXPECTED TO REMAIN
QUITE HIGH THROUGH THE DURATION OF THE HEAVIEST PRECIPITATION, BUT
ARE EXPECTED TO LOWER LATER IN THE WEEK. PLEASE SEE THE HYDROLOGY
SECTION BELOW FOR MORE INFORMATION ON EXPECTED RAINFALL RATES,
TOTALS, AND SNOW LEVEL INFORMATION.
IN ADDITION TO PERIODS OF HEAVY RAIN, GUSTY SOUTH WINDS ARE
EXPECTED. STRONGEST WINDS EXPECTED DURING THE DAY WEDNESDAY. PEAK
WIND GUSTS OF 60-70 MPH, LOCALLY UP TO 75-80 MPH POSSIBLE ON THE
DESERT SLOPES OF THE SAN BERNARDINO COUNTY MOUNTAINS WITH GUSTS 45-
60 MPH INTO THE HIGH DESERT. WINDS WILL STAY ELEVATED IN SAN
BERNARDINO COUNTY MOUNTAINS AND HIGH DESERT INTO THURSDAY. FOR THE
COASTS AND VALLEYS GUST OF 30-45 MPH ARE EXPECTED, WITH THE
STRONGEST WINDS EXPECTED WITH THE MAIN BAND OF RAIN.
MODELS ARE COMING INTO BETTER AGREEMENT THAT THE NEXT ROUND OF
WIDESPREAD MODERATE TO HEAVY RAIN WILL BE THURSDAY EVENING INTO
FRIDAY. GUIDANCE IS INDICATING A MORE ORGANIZED BAND OF RAIN WILL
MOVE ACROSS THE AREA SOMETIME LATE THURSDAY INTO FRIDAY, WITH SOME
LINGERING SCATTERED SHOWERS THROUGH THE DAY FRIDAY EVENTUALLY
TAPERING OFF SOME TIME SATURDAY. IN ADDITION TO RAIN AND MOUNTAIN
SNOW (7000 FT AND ABOVE), WINDS ARE EXPECTED TO INCREASE OVER THE
MOUNTAINS AND INTO THE DESERTS, WITH TIMING OF THE STRONGEST
WINDS SHAPING UP TO BE SOMETIME THURSDAY NIGHT INTO FRIDAY.
OVERALL, RAINFALL RATES AND AMOUNTS ARE STARTING TO SHAPE UP TO
LOOK LESS THAN WHAT IS EXPECTED FOR WEDNESDAY, BUT ADDITIONAL
RAINFALL ON ALREADY SATURATED SOILS MAY RESULT IN ADDITIONAL AREAS
OF FLOODING.
AVIATION
232130Z....A HIGH BROKEN TO OVERCAST LAYER OF CLOUDS WILL CONTINUE
TO COVER THE AREA AROUND 20-25K FT MSL THROUGH THE TAF PERIOD. LOW
CLOUDS WITH BASES 1500-5000 FT MSL EXPECTED ALONG THE COAST WITH
INLAND AREAS GETTING AS LOW AS 300-700FT MSL AFTER 12-14Z WEDNESDAY.
LIGHT RAIN CHANCES THROUGH THE DAY TODAY WITH INCREASING CHANCES
THROUGH THIS EVENING AND OVERNIGHT. VIS REDUCTIONS 1-4 SM ARE
EXPECTED AS RAIN CHANCES INCREASE. THE MAIN RAIN BAND WILL MOVE
IN FROM THE NORTHWEST TO THE SOUTHEAST TOWARDS THE END OF THE TAF
PERIOD AND WILL BRINGING MODERATE TO HEAVY PRECIPITATION WITH VIS
REDUCTIONS 1-3 SM ALONG WITH STRONG SOUTH TO SE WINDS.
MARINE
THE APPROACHING STORM SYSTEM HAS INCREASED WINDS OUT OF THE SOUTH TO
SOUTHEAST AND WILL BUILD SEAS THIS AFTERNOON. WINDS INITIALLY AROUND
15-20 KTS GUSTING TO 25 KTS WILL INCREASE EARLY WEDNESDAY TO GALE
FORCE, WITH WIND GUSTS UPWARDS OF 35 KTS. THIS WILL BRING STEEP
COMBINED SEAS OF 6-9 FEET. ADDITIONALLY, PERIODS OF MODERATE TO
HEAVY RAIN WEDNESDAY WILL LEAD TO AREAS OF POOR VISIBILITY. WINDS
DIMINISH SLIGHTLY LATE WEDNESDAY THROUGH EARLY THURSDAY, BUT WINDS
AND SEAS WILL REMAIN HAZARDOUS TO SMALL CRAFT. ANOTHER ROUND OF
STRONGER SOUTHWEST WINDS EXPECTED LATE THURSDAY INTO EARLY FRIDAY,
WITH GUSTS AROUND 25 KTS. WINDS WEAKEN AND TURN NORTHWESTERLY
FRIDAY.
BEACHES
STRENGTHENING SOUTH WINDS TONIGHT INTO WEDNESDAY WILL LEAD TO
ELEVATED SURF 5 TO 8 FEET WITH SETS TO 9 FEET, HIGHEST FOR SOUTH-
FACING BEACHES. THIS WILL LEAD TO HAZARDOUS SWIMMING CONDITIONS, AS
WELL AS POSSIBLY MINOR TIDAL OVERFLOW FOR SOUTH-FACING BEACHES FROM
A COMBINATION OF WINDS AND ELEVATED SURF THROUGH WEDNESDAY,
ESPECIALLY DURING HIGH TIDES. WINDS DIMINISH ALONG WITH SURF LATE
WEDNESDAY, BUT MORE BREEZY WINDS ALONG WITH LARGE FRESH SWELL WILL
LEAD TO SURF BUILDING AGAIN FRIDAY-SATURDAY. A SURF ADVISORY IS IN
EFFECT FROM TONIGHT TO SATURDAY AFTERNOON.
HYDROLOGY
SCATTERED MOSTLY LIGHT SHOWERS ARE EXPECTED CONTINUE INTO THIS
EVENING. RAIN IS EXPECTED TO BECOME HEAVY AT TIMES LATE TONIGHT
ALONG THE SOUTH SLOPES OF THE SAN BERNARDINO COUNTY MOUNTAINS WITH
HEAVY RAINFALL SPREADING SOUTHWARD ACROSS THE AREA FOR LATE
TONIGHT THROUGH WEDNESDAY MORNING WITH THE HEAVY RAINFALL
CONTINUING THROUGH WEDNESDAY EVENING. SCATTERED SHOWERS MAY
CONTINUE ON THURSDAY (MOST LIKELY IN THE MORNING) FOR SOME
LOCATIONS WITH ANOTHER ROUND OF MORE WIDESPREAD SHOWERS FOR
THURSDAY NIGHT INTO FRIDAY. THE SNOW LEVEL WILL RISE TO ABOVE 9000
FEET FOR EARLY WEDNESDAY MORNING, FALL TO AROUND 7000 FEET ON
THURSDAY THROUGH FRIDAY MORNING, THEN FALL TO 4500 TO 5000 FEET
FOR EARLY SATURDAY MORNING AS PRECIPITATION TAPERS OFF.
THROUGH WEDNESDAY NIGHT, FOR ORANGE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES, RAINFALL COULD RANGE FROM 2.5 TO 3.5 INCHES NEAR THE COAST
TO 6 TO 8 INCHES ON THE COASTAL SLOPES OF THE SAN BERNARDINO COUNTY
MOUNTAINS WITH ISOLATED TOTALS TO AROUND 12 INCHES ON THE COASTAL
SLOPES TO THE WEST OF THE CAJON PASS. RAINFALL WILL DECREASE FROM
NORTH TO SOUTH WITH RAINFALL ACROSS FAR SOUTHERN SAN DIEGO COUNTY
AROUND 1.5 INCH NEAR THE COAST TO 2.5 INCHES IN THE MOUNTAINS. FOR
THE HIGH DESERT, 1.5 INCH TO 3.5 INCHES NEAR THE FOOTHILLS OF THE
SAN GABRIEL MOUNTAINS IS EXPECTED WITH 0.75 TO 1.5 INCH FOR THE
LOWER DESERTS. HOURLY RAINFALL RATES ARE EXPECTED TO BE 0.50-1 INCH
PER HOUR, LOCALLY HIGHER IN ANY CONVECTIVE BANDS OR THUNDERSTORMS
THAT DEVELOP.
THE SAN BERNARDINO COUNTY MOUNTAINS ARE PART OF A HIGH RISK AREA FOR
EXCESSIVE RAINFALL FOR WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT,
AREAS WITH A HEIGHTENED RISK FOR DAMAGING AND POTENTIALLY LIFE-
THREATENING FLASH FLOODING. HOURLY RAINFALL RATES OF 0.50-1 INCH ARE
LIKELY FOR SEVERAL HOURS ON THE COASTAL SLOPES OF THE EASTERN SAN
GABRIEL MOUNTAINS FROM BEFORE DAWN ON WEDNESDAY THROUGH WEDNESDAY
AFTERNOON, LOCALLY TO AROUND 1 INCH PER HOUR FROM THUNDERSTORMS OR
BANDS OF HEAVIER SHOWERS.
THE SAN DIEGO RIVER AT FASHION VALLEY AND THE SANTA MARGARITA RIVER
AT YSIDORA ARE CURRENTLY EXPECTED TO REACH ACTION/MONITOR STAGE.
BASED ON CURRENT FORECAST, THE SAN DIEGO RIVER IS EXPECTED TO PEAK
AT 7.5 FT WEDNESDAY NIGHT WITH THE SANTA MARGARITA EXPECTED TO PEAK
AT 11.1 FT LATE WEDNESDAY NIGHT/EARLY THURSDAY MORNING. IF HEAVIER
RAIN DEVELOPS OVER EITHER OF THOSE TWO RIVER BASINS, THE RIVERS MAY
EXCEED THEIR CURRENTLY FORECAST PEAKS.
ADDITIONAL RAINFALL DURING THE DAY ON THURSDAY FROM SHOWERS WILL
RANGE FROM AROUND 0.50 INCH NORTH TO LESS THAN 0.25 INCH FURTHER
SOUTH, LOCALLY TO AROUND 1 INCH ON THE COASTAL SLOPES OF THE SAN
BERNARDINO COUNTY MOUNTAINS. LOCALLY HIGHER AMOUNTS POSSIBLE WHERE
ANY CONVECTIVE SHOWERS OR THUNDERSTORMS DEVELOP THURSDAY MORNING.
FOR THURSDAY NIGHT AND FRIDAY, A WEAKER ATMOSPHERIC RIVER WILL BRING
ANOTHER ROUND OF MORE WIDESPREAD SHOWERS WITH A SLIGHT CHANCE OF
THUNDERSTORMS. FOR ORANGE AND SOUTHWESTERN SAN BERNARDINO COUNTIES,
RAINFALL COULD RANGE FROM AROUND 0.75 INCH NEAR THE COAST TO 1 TO 2
INCHES ON THE COASTAL SLOPES OF THE SAN BERNARDINO COUNTY MOUNTAINS
WITH ISOLATED TOTALS TO AROUND 3 INCHES ON THE COASTAL SLOPES TO THE
WEST OF THE CAJON PASS. RAINFALL WILL DECREASE FROM NORTH TO SOUTH
WITH RAINFALL ACROSS FAR SOUTHERN SAN DIEGO COUNTY AROUND 0.25 TO
0.50 INCH. FOR THE HIGH DESERT, 0.25 TO 0.50 INCH IS EXPECTED WITH
LESS THAN 0.25 INCH FOR THE LOWER DESERTS. FIRST TAKE OF HOURLY
RAINFALL RATES FOR LATE THURSDAY INTO FRIDAY LOOK TO RANGE ANYWHERE
FROM 0.3-0.75 INCHES PER HOUR. IT'S POSSIBLE THAT THERE WILL BE
ADDITIONAL CHANCES OF THUNDERSTORMS SOMETIME LATE THURSDAY INTO
FRIDAY, WITH HIGHER RAINFALL RATES EXPECTED WHERE THUNDERSTORMS
DEVELOP.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...HIGH SURF ADVISORY FROM 11 PM THIS EVENING TO 11 AM PST SATURDAY
FOR ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL
AREAS.
WIND ADVISORY FROM 3 AM TO 10 PM PST WEDNESDAY FOR ORANGE COUNTY
COASTAL AREAS-ORANGE COUNTY INLAND AREAS-SAN BERNARDINO AND
RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO COUNTY
COASTAL AREAS-SAN DIEGO COUNTY VALLEYS-SANTA ANA MOUNTAINS
AND FOOTHILLS.
FLOOD WATCH FROM LATE TONIGHT THROUGH LATE WEDNESDAY NIGHT FOR
SAN DIEGO COUNTY COASTAL AREAS-SAN DIEGO COUNTY DESERTS-SAN
DIEGO COUNTY MOUNTAINS-SAN DIEGO COUNTY VALLEYS.
FLOOD WATCH FROM 10 PM PST THIS EVENING THROUGH WEDNESDAY
EVENING FOR APPLE AND LUCERNE VALLEYS-COACHELLA VALLEY-
ORANGE COUNTY COASTAL AREAS-ORANGE COUNTY INLAND AREAS-
RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND
EMPIRE-SAN GORGONIO PASS NEAR BANNING-SANTA ANA MOUNTAINS
AND FOOTHILLS.
HIGH WIND WARNING UNTIL 3 PM PST THURSDAY FOR APPLE AND LUCERNE
VALLEYS-SAN BERNARDINO COUNTY MOUNTAINS.
PZ...GALE WARNING UNTIL 4 PM PST WEDNESDAY FOR COASTAL WATERS FROM
SAN MATEO POINT TO THE MEXICAN BORDER AND OUT TO 10 NM-
WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING
10 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND.
PUBLIC...CO
AVIATION/MARINE/BEACHES...VILLAFANE
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