203
FXUS66 KSGX 172151
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
151 PM PST MON FEB 17 2025
SYNOPSIS
COOLING WILL SPREAD INLAND THROUGH TUESDAY AS THE MARINE LAYER
RETURNS AND DEEPENS FOR TONIGHT INTO TUESDAY MORNING. THERE WILL
BE PATCHY LOW CLOUDS AND LOCALLY DENSE FOG NEAR THE COAST EARLY
THIS MORNING WITH MORE WIDESPREAD COASTAL LOW CLOUDS SPREADING
INTO PORTIONS OF THE INLAND VALLEYS FOR LATE TONIGHT INTO TUESDAY
MORNING. PATCHY FOG, ESPECIALLY ALONG THE COAST, WILL BE POSSIBLE
AGAIN TOMORROW AND WEDNESDAY NIGHT. THERE WILL BE GUSTY WEST
WINDS FOR THE MOUNTAINS AND DESERTS FOR TODAY AND TONIGHT WITH THE
STRONGEST GUSTS ALONG THE DESERT SLOPES OF THE MOUNTAINS TO 40 TO
50 MPH. SLIGHTLY WARMER ON WEDNESDAY, SLIGHTLY COOLER ON
THURSDAY, THEN A WARMING TREND THROUGH NEXT WEEKEND WITH SUNDAY
AND MONDAY HIGH TEMPERATURES AS MUCH AS 10 TO 15 DEGREES ABOVE
AVERAGE FOR THE MOUNTAINS AND INLAND VALLEYS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
TONIGHT THROUGH TOMORROW NIGHT...
THE LATEST HIGH RES GUIDANCE HAS BEEN CONSISTENT WITH THE FORMATION
OF ANOTHER STRONGER EDDY TONIGHT, WHICH WILL ALLOW FOR THE RETURN OF
THE MARINE LAYER, AND THICKENING, WITH SOME FOG AND LIGHT DRIZZLE
BEING POSSIBLE, ESPECIALLY FOR THE EAST SAN DIEGO INLAND VALLEYS AND
WITHIN THE INLAND EMPIRE. GIVEN THAT CEILINGS OF THE LOW LEVEL
CLOUDS WILL INITIALLY BEGIN CLOSER TO THE SURFACE, THERE COULD ALSO
BE SOME PATCHY AREAS OF FOG DEVELOPING OVER THE WATERS AS WELL.
HOWEVER, I DO NOT HAVE HIGH CONFIDENCE OF THIS, GIVEN THE
DEVELOPMENT OF THE COASTAL EDDY, WHICH SHOULD HELP TO LIFT CEILINGS
ABOVE THE SEA SURFACE. STRONGER WIND GUSTS OVER THE HIGHER
ELEVATIONS WILL CONTINUE TO COME DOWN OVERNIGHT AND RETURN TO BEING
MORE DIURNAL BY TOMORROW. THERE WILL BE SOME COOLER TEMPERATURES FOR
HIGHS TOMORROW AS WEAK ONSHORE FLOW PREVAILS BY LATER IN THE
AFTERNOON, WHICH WILL BE CLOSER TO THE SEASONAL AVERAGE. FOR
TOMORROW NIGHT, HIGH PRESSURE BUILDING IN STRONGER AND THE LACK OF A
COASTAL EDDY BEING PRESENT WILL ALLOW FOR THERE TO BE SOME LOWER
CEILINGS FOR THE MARINE LAYER AS IT RETURNS, AND THEREFORE PATCHY
FOG OVER THE COASTAL WATERS WILL BE MORE LIKELY. HAVING SAID THAT, I
DO NOT BELIEVE THAT THIS WILL BE WIDESPREAD IN GENERAL, AND MOSTLY
CONFINED TO THE COASTAL AREAS FROM CARLSBAD AND SOUTHWARD. LOWS
TOMORROW NIGHT WILL ALSO BE SLIGHTLY MODIFIED AND THEREFORE A LITTLE
WARMER THAN WHAT IS FORECAST FOR LOWS TONIGHT.
WEDNESDAY THROUGH EARLY NEXT WEEK...
BECAUSE OF THE HIGH PRESSURE AND WEAK ONSHORE FLOW RETURNING ON
WEDNESDAY, BY LATER IN THE EVENING AND THROUGHOUT THE NIGHT INTO
THURSDAY MORNING, THERE COULD BE SOME AREAS OF FOG DEVELOPING AGAIN,
ESPECIALLY FOR THE COASTAL AREAS. DETERMINISTIC MODELS ARE STILL IN
RELATIVELY CLOSE AGREEMENT WITH THE PROPAGATION OF A MAJOR SHORTWAVE
TROUGH PERFORMING AN "INSIDE SLIDER" TRACK, WHICH WILL ALLOW FOR
INCREASING OFFSHORE WINDS BRIEFLY IN ITS WAKE FROM THURSDAY
AFTERNOON THROUGH FRIDAY MORNING, ALTHOUGH AT THIS TIME, THESE WINDS
LOOK TO REMAIN BELOW THE THRESHOLD TO BE CLASSIFIED AS SANTA ANA
WINDS. IN ADDITION WITH THESE OFFSHORE WINDS ADVECTING IN SOME DRIER
AIR, THE FURTHER BUILDING OF THE RIDGE AND STRENGTHENING OF THE
SURFACE HIGH OVER THE WESTERN STATES WILL LEAD TO WARMER AND DRIER
CONDITIONS FOR THIS UPCOMING WEEKEND, WITH TEMPERATURES WELL ABOVE
THE SEASONAL AVERAGE FOR THIS TIME OF YEAR. BY SUNDAY AND MONDAY,
MUCH OF THE INLAND VALLEYS WILL HAVE HIGHS TOP OUT IN THE UPPER
70S TO LOW 80S, WITH THE DESERTS GETTING CLOSE TO THE 90 DEGREE MARK.
AVIATION
172100Z...COAST/VALLEYS...LOW CLOUDS OVER MARINE WATERS BASED AROUND
1000 FEET MSL ARE SLOWLY PUSHING ONSHORE AND WILL MOVE INTO COASTAL
AREAS 01-03Z. BKN-OVC CLOUDS AT 1000-1500 FEET MSL TONIGHT, RISING
TO 1500-2000 FEET MSL AND FILLING INTO INLAND AREAS AS COASTAL EDDY
DEVELOPS OVERNIGHT INTO TUESDAY. SCATTER OUT 17-19Z. SOME VIS
REDUCTIONS OVER HIGHER COASTAL TERRAIN. OTHERWISE, SCT-BKN HIGH
CLOUDS TODAY AND TONIGHT.
MOUNTAINS/DESERTS...WESTERLY WINDS THROUGH TONIGHT, WITH SURFACE
GUSTS 25-45 KTS, STRONGEST OVER THE RIDGES, DESERT SLOPES, AND THE
HIGH DESERT. MODERATE UP/DOWNDRAFTS POSSIBLE IN LEE OF RIDGES.
PATCHY BLDU REDUCING VIS IN THE DESERT. SCT-BKN HIGH CLOUDS TODAY
AND TONIGHT.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE ANTICIPATED THROUGH SATURDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...STEWEY
AVIATION/MARINE...CSP/WESTERINK
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