371
FXUS66 KSGX 270016
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
416 PM PST FRI DEC 26 2025
SYNOPSIS
BANDS OF SHOWERS WITH A SLIGHT CHANCE OF EMBEDDED THUNDERSTORMS
WILL SLOWLY MOVE SOUTHEASTWARD ACROSS THE AREA THROUGH THIS
EVENING. DRYING WILL DEVELOP OVER THE WEEKEND AND CONTINUE INTO
EARLY NEXT WEEK, WITH PERIODS OF WEAK TO MODERATE STRENGTH GUSTY
SANTA ANA WINDS FOR SUNDAY THROUGH TUESDAY. SLIGHT WARMING WILL
ACCOMPANY THE OFFSHORE FLOW FOR MONDAY AND TUESDAY. A LOW PRESSURE
SYSTEM FROM THE SOUTHWEST COULD BRING A RETURN OF PRECIPITATION
FOR WEDNESDAY THROUGH FRIDAY.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
EXTENSIVE TROUGHING OVER THE WEST COAST OF THE US, WITH EMBEDDED
SHORTWAVE TROUGHS, WILL CONTINUE TO BRING PRECIPITATION TO SOCAL
THROUGH TONIGHT. BANDS OF SHOWERS WITH A SLIGHT CHANCE OF
EMBEDDED THUNDERSTORMS, ASSOCIATED WITH A FRONTAL BOUNDARY, WILL
SLOWLY MOVE SOUTHEASTWARD ACROSS THE AREA TODAY THROUGH THIS
EVENING. THE CONVECTIVE ELEMENTS WITHIN THE BAND ARE MOVING TO THE
NORTHEAST AT ABOUT 30 MPH WITH THE STEERING FLOW ALOFT. THIS
PATTERN OF FLOW WILL RESULT IN OROGRAPHIC ENHANCEMENT OF RAINFALL
AMOUNTS ON THE COASTAL MOUNTAIN SLOPES - ESPECIALLY THE SAN
BERNARDINO MOUNTAINS. SHOWERS COULD LINGER IN SAN DIEGO COUNTY
OVERNIGHT AFTER THE PASSAGE OF THE FRONTAL BOUNDARY WHEN THE WINDS
BECOME NORTHWESTERLY AND LOW LEVEL CONVERGENCE DOWNSTREAM OF
OFFSHORE ISLANDS PRODUCES CONVECTION IN THE COLD AIR BEHIND THE
FRONT.
AS THE LOW PRESSURE TROUGH MOVES INLAND AND A HIGH PRESSURE RIDGE
BUILDS OVER THE PAC NORTHWEST, A DRYING TREND DEVELOPS FOR THE
WEEKEND INTO EARLY NEXT WEEK. FOR SUNDAY THROUGH TUESDAY, WEAK TO
MODERATE OFFSHORE FLOW DEVELOPS. NORTHEAST SANTA ANA WINDS GUSTING
TO 35-45 MPH IN AND BELOW THE MTN PASSES AND CANYONS ARE EXPECTED
FOR SUNDAY AND MONDAY.
BY MONDAY, A CLOSED UPPER LOW DEVELOPS TO OUR SOUTHWEST WHILE THE
HIGH PRESSURE RIDGE BUILDS TO OUR NORTH. THIS WILL LIKELY BRING
A WARMING TREND FOR SUNDAY- WEDNESDAY. TUESDAY WILL LIKELY BE THE
WARMEST DAY WITH TEMPERATURES IN THE 70S (AS MUCH AS 5-6 DEGREES
ABOVE AVERAGES) WEST OF THE MTNS.
FOR THE MIDDLE TO THE END OF NEXT WEEK...A LOW PRESSURE SYSTEM
FROM THE GULF OF ALASKA WILL APPROACH THE WEST COAST, DISPLACING
THE HIGH PRESSURE RIDGE AND DRAWING THE CLOSED LOW TO OUR
SOUTHWEST NORTHEASTWARD INTO THE MEAN FLOW OVER SOCAL. THERE ARE
SIGNIFICANT DIFFERENCES AMONG NUMERICAL MODEL SOLUTIONS WITH
RESPECT TO HOW THIS PATTERN WILL EVOLVE BUT AN INCREASING NUMBER
OF ENSEMBLE MEMBERS ARE INDICATING THE POSSIBILITY OF
PRECIPITATION FOR SOCAL BETWEEN NEXT WEDNESDAY AND FRIDAY. AT THIS
TIME, PRECIPITATION AMOUNTS ARE HIGHLY UNCERTAIN.
SEE THE HYDROLOGY DISCUSSION FOR PRECIPITATION DETAILS.
AVIATION
270000Z....COASTS/VALLEYS...-SHRA ACROSS ORANGE COUNTY AND THE
INLAND EMPIRE WILL PUSH SOUTH AND EAST INTO SAN DIEGO COUNTY IN THE
NEXT FEW HOURS. MVFR CIGS/VIS EXPECTED FOR MOST AREAS WITH
INTERMITTENT IFR CIGS/VIS IN LOCALLY HEAVIER RA. MOST OF THE
PRECIPITATION AND ASSOCIATED LOW CLOUDS WILL EXIT THE COASTAL BASIN
BY 06Z WITH ONLY FEW/SCT -SHRA, THEREAFTER. SCT CLOUDS BASED 3000-
6000 FT MSL THROUGH THE AFTERNOON ON SAT WITH ISOLATED SHRA NEAR THE
COASTLINE 15-21Z.
MOUNTAINS/DESERTS
WIDESPREAD MID LEVEL CLOUDS BASED 4000-6000 FT
MSL ALONG WITH RA IN THE MTNS WILL SLOWLY EXIT THE REGION 06-09Z
SAT. SCT -SHRA IN THE LOW DESERTS MAY INTERMITTENTLY LOWER CIGS/VIS
TO MVFR IN THE LOW DESERTS 03-09Z. CLOUDS WILL LINGER ALONG COASTAL
SLOPES THROUGH 18Z. SOUTHWESTERLY WINDS TURNING WESTERLY 06-09Z AND
GUSTING 25-35 KNOTS AND DOWNWIND OF DESERT SLOPES THROUGH 18Z.
LOCALLY HIGHER GUSTS THROUGH MOUNTAIN PASSES. MOD UP/DOWNDRAFTS
DOWNWIND OF THE MOUNTAINS.
MARINE
SOUTH TO SOUTHWEST WINDS GUSTING TO 20 KTS WILL TURN NORTHWEST THIS
EVENING AND GRADUALLY DECREASE LATE TONIGHT INTO SATURDAY.
OTHERWISE, NO HAZARDOUS MARINE WEATHER EXPECTED THROUGH WEDNESDAY.
BEACHES
WESTERLY SWELL (250-270 DEGREES) WILL LEAD TO SURF HEIGHTS
INCREASING TO 5 TO 8 FEET THROUGH EARLY SATURDAY. HIGHEST SURF IS
EXPECTED FOR WEST-FACING BEACHES. A HIGH SURF ADVISORY REMAINS IN
EFFECT UNTIL LATE SATURDAY MORNING.
HYDROLOGY
ADDITIONAL RAINFALL THROUGH TONIGHT FOR ORANGE AND SOUTHWESTERN
SAN BERNARDINO COUNTIES IS EXPECTED TO RANGE FROM 0.50 TO 0.75
INCH NEAR THE COAST TO 1 TO 2 INCHES IN THE SAN BERNARDINO COUNTY
MOUNTAINS, LOCALLY UP TO 3 INCHES ON THE COASTAL SLOPES OF THE
EASTERN SAN GABRIEL MOUNTAINS. AMOUNTS WILL DECREASE FROM NORTH TO
SOUTH WITH AROUND 0.25-0.35 INCH EXPECTED OVER FAR SOUTHERN SAN
DIEGO COUNTY.
BY SATURDAY MORNING, HIGH-RESOLUTION MODELS INDICATE A 50-70
PERCENT PROBABILITY OF EXCEEDING 2 INCHES OF RAIN IN THE SAN
BERNARDINO MOUNTAINS AND ABOUT A 20 PERCENT CHANCE IN THE SANTA
ANA MOUNTAINS.
THE SNOW LEVEL IS NOW ABOVE 7500 FEET, BUT WILL FALL TO AROUND
4500 FEET BY LATE TONIGHT. SNOWFALL IN THE SAN BERNARDINO COUNTY
MOUNTAINS OF 1 TO 3 INCHES IS POSSIBLE DOWN TO AROUND 7000 FEET
WITH SNOWFALL OF 8 TO 12 INCHES ABOVE 8000 FEET.
PRELIMINARY PRECIPITATION ESTIMATES FOR NEXT WED THROUGH FRI:
0.25"-0.50" IN THE LOW DESERTS, 0.40"-0.75" INCH IN THE HIGH
DESERTS, 1.25"-1.60" IN THE COASTAL AREAS AND VALLEYS TO 2-3
INCHES ON THE COASTAL MTN SLOPES.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...HIGH SURF ADVISORY UNTIL 11 AM PST SATURDAY FOR ORANGE COUNTY
COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.
PZ...NONE.
PUBLIC...PG
AVIATION/MARINE/BEACHES...KW
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