685
FXUS66 KSGX 030401
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
901 PM PDT THU OCT 2 2025
SYNOPSIS
COOLER CONDITIONS WITH STRONGER WESTERLY WINDS IN THE MOUNTAINS
AND DESERTS FOR FRIDAY. IN ADDITION, THE MARINE LAYER WILL DEEPEN
WITH LOW CLOUDS EXPECTED TO SPREAD INTO PORTIONS OF THE INLAND
VALLEYS TONIGHT AND FRIDAY NIGHT. SLIGHTLY WARMER SATURDAY WEST
OF THE MOUNTAINS WITH WEAK OFFSHORE FLOW. COOLER CONDITIONS
EXPECTED SUNDAY AND MONDAY WITH WARMING NEXT TUESDAY THROUGH
THURSDAY.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
THIS EVENING...THE MARINE LAYER IS ABOUT 1500 FT DEEP. SIMILAR TO
THIS TIME YESTERDAY, HOWEVER LOW CLOUDS ARE FORMING IN THE COASTAL
AREAS AND SPREADING INLAND AS THE INVERSION IS A LITTLE STRONGER
THAN YESTERDAY. BY SUNRISE, LOW CLOUDS WILL LIKELY COVER MOST OF
THE LOW ELEVATIONS WEST OF THE MTNS. HIGH TEMPERATURES TODAY WERE
A FEW DEGREES HIGHER THAN YESTERDAY, MAINLY IN THE INLAND VALLEYS
AND DESERTS. ELSEWHERE, TEMPERATURES WERE SIMILAR TO YESTERDAY.
FROM PREVIOUS DISCUSSION...
A TROUGH OF LOW PRESSURE CURRENTLY OVER THE COAST WILL MOVE INTO
CALIFORNIA, FORMING A CLOSED UPPER LOW OVER NORTHERN/CENTRAL CA
ON FRIDAY BEFORE MOVING EAST INTO NEVADA ON SATURDAY. THIS WILL
BRING 3 TO 7 DEGREES OF COOLING TO INLAND AREAS ON FRIDAY, WITH AN
INCREASE IN WESTERLY WINDS FOR THE MOUNTAINS AND DESERTS. WINDS
WILL PEAK IN STRENGTH FRIDAY AFTERNOON AND EVENING. WIND GUSTS 35
TO 50 MPH EXPECTED OVERALL, WITH THE POTENTIAL FOR GUSTS UP TO 55
MPH IN PORTIONS OF THE SAN DIEGO DESERTS AND UP TO 60 MPH THROUGH
THE SAN GORGONIO PASS. ADDITIONALLY, WITH THE INCREASE IN ONSHORE
FLOW THE MARINE LAYER IS EXPECTED TO DEEPEN. AREAS OF LOW CLOUDS
ARE EXPECTED TO REACH INTO THE VALLEYS FOR TONIGHT INTO FRIDAY
MORNING.
AS THE UPPER LEVEL LOW MOVES OVER NEVADA SATURDAY, SFC PRESSURE
GRADIENTS WILL BECOME WEAKLY OFFSHORE ON SATURDAY. THE NORTH/NORTHEASTERLY
WINDS ASSOCIATED WITH THE OFFSHORE FLOW ARE EXPECTED TO BE FAIRLY
WEAK AND LOCALIZED TO THE SAN BERNARDINO AND SANTA ANA COASTAL
MOUNTAIN SLOPES. WHILE THE MARINE LAYER WILL STILL BE FAIRLY DEEP,
ANY LOW CLOUDS THAT DEVELOP FRIDAY NIGHT INTO SATURDAY ARE
EXPECTED TO CLEAR FAIRLY QUICKLY IN THE INLAND EMPIRE AND ORANGE
COUNTY. HIGHS ON SATURDAY ARE EXPECTED TO BE A FEW DEGREES WARMER
THAN FRIDAY WEST OF THE MOUNTAINS, LIKELY DUE TO THE WEAK OFFSHORE
FLOW. TEMPERATURES IN THE DESERTS WILL CONTINUE TO COOL A FEW
DEGREES INTO SATURDAY.
A BROAD TROUGH OF LOW PRESSURE WILL SET UP OVER THE WESTERN UNITED
STATES ON SUNDAY. THIS WILL RESULT IN A FEW DEGREES OF COOLING WEST
OF THE MOUNTAINS, WITH ADDITIONAL COOLING EXPECTED INTO MONDAY FOR
MOST LOCATIONS. FOR NEXT TUESDAY AND WEDNESDAY, THE PATTERN BECOMES
A LITTLE MORE UNCERTAIN WITH ENSEMBLE GUIDANCE STRUGGLING TO PIN
DOWN THE AMPLITUDE AND POSITION OF THE TROUGH. THE SOLUTIONS WITH
A DEEPER TROUGH OVER CALIFORNIA WOULD CONTINUE THE COOLER
CONDITIONS WHILE THE SOLUTIONS WITH THE TROUGH TO OUR EAST WITH
WEAK RIDGING OVER CALIFORNIA WOULD BRING SLIGHTLY WARMER
CONDITIONS. CURRENT FORECAST FOLLOWS THE NBM WHICH LEANS TOWARDS
THE WARMER SOLUTIONS FOR NEXT TUESDAY THROUGH THURSDAY.
AVIATION
030345Z....COASTS/VALLEYS...LOW CLOUDS BASED 1300-1800 WILL CONTINUE
TO MOVE INTO COASTAL AREAS THROUGH 07Z, THEN INTO THE INLAND EMPIRE
08-13Z. OCCASIONAL, BRIEF SCATTER OUT POSSIBLE AT SITES OVERNIGHT,
BUT PREVAILING CONDITIONS BKN-OVC EXPECTED. CIGS WILL RISE SLIGHTLY
OVERNIGHT TO ABOUT 1600-2200 FT MSL BY 15Z. CLOUDS SCATTER INLAND 15-
18Z (LATEST FOR AREAS VCNTY KONT), THEN FOR COASTAL AREAS 17-19Z,
THOUGH ISOLATED PATCHES OF LOW CLOUDS COULD LINGER ALONG THE COAST
THROUGH 20Z. BREEZIER THAN AVERAGE WEST TO NORTHWEST WINDS EXPECTED
FRIDAY AFTERNOON, WITH GUSTS TO AROUND 20 KTS THROUGH AROUND 4/02Z.
LOW CLOUDS WILL REFORM IN PATCHES AFTER 4/00Z WITH SIMILAR BASES,
AND LIKELY FORM INITIALLY AGAINST THE FOOTHILLS THEN GRADUALLY
SPREAD WEST.
MOUNTAINS/DESERTS...MOSTLY CLEAR AND VFR CONDITIONS TONIGHT AND
TOMORROW. STRONGER WINDS OUT OF THE WEST PICK UP AND BECOME MORE
WIDESPREAD AFTER 18Z FRI THROUGH THE LATE AFTERNOON, ESPECIALLY FOR
DESERTS AND DESERT FOOTHILLS, WITH GUSTS GENERALLY 25-35 KTS EXCEPT
FOR TYPICALLY WINDY SPOTS GUSTING TO AROUND 45 KTS.
MARINE
NORTHWEST WINDS FRIDAY AFTERNOON AND EVENING OVER THE OUTER WATERS
WILL LEAD TO HAZARDOUS CONDITIONS FOR SMALL CRAFT, AS WINDS WILL
PERIODICALLY EXCEED 25 KTS, LEADING TO CHOPPY SEAS 5 TO 8 FEET.
WINDS WILL BE STRONGEST IN THE VICINITY OF SAN CLEMENTE ISLAND.
WINDS CALM LATE FRIDAY, AND NO HAZARDOUS MARINE CONDITIONS ARE
EXPECTED SATURDAY THROUGH MONDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...WIND ADVISORY FROM 4 PM FRIDAY TO 5 AM PDT SATURDAY FOR SAN
DIEGO COUNTY DESERTS.
WIND ADVISORY FROM 6 AM FRIDAY TO 5 AM PDT SATURDAY FOR SAN
GORGONIO PASS NEAR BANNING.
PZ...SMALL CRAFT ADVISORY FROM 11 AM TO 11 PM PDT FRIDAY FOR WATERS
FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 10 TO
60 NM OUT INCLUDING SAN CLEMENTE ISLAND.
PUBLIC...PG
AVIATION/MARINE...CSP
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