438
FXUS66 KSGX 120322
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
822 PM PDT THU SEP 11 2025
SYNOPSIS
GRADUAL WARMING EXPECTED INTO THE MIDDLE OF NEXT WEEK. NIGHT AND
MORNING LOW CLOUDS AND FOG WILL BE PRESENT EACH DAY INTO EARLY
NEXT WEEK ALONG THE COAST AND INTO PORTIONS OF THE VALLEYS. SOME
MONSOON AND REMNANT TROPICAL MOISTURE MAY RETURN FOR THE MIDDLE
AND LATTER PART OF NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
EVENING UPDATE...
AFTER CLEARING NICELY THIS AFTERNOON, LOW CLOUDS HAVE BEGUN TO
REDEVELOP ALONG THE SAN DIEGO COUNTY COAST THIS EVENING. THE 00Z
KNKX SOUNDING SHOWS THE MARINE INVERSION BASED NEAR 2500 FT MSL,
DEEP ENOUGH FOR LOW CLOUDS TO SPREAD INTO THE VALLEYS AGAIN
TONIGHT. NO CHANGES TO THE FORECAST THIS EVENING.
PREVIOUS DISCUSSION....
THE UPPER LEVEL LOW PRESSURE SYSTEM CONTINUES TO MOVE EAST, REACHING
THE ROCKIES BY SATURDAY. IN THE ABSENCE OF THE LOW, AN UPPER LEVEL
RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD OVER THE WEST COAST
SATURDAY. AS A RESULT, A GRADUAL WARMING TREND WILL OCCUR FOR THE
END OF THIS WEEK INTO THE WEEKEND. EVEN WITH THE WARMING, HIGH
TEMPERATURES WILL REMAIN BELOW AVERAGE THROUGH SUNDAY.
ON SUNDAY AN AREA OF LOW PRESSURE WILL DEVELOP AND LINGER OFF THE
SOUTHERN CALIFORNIA COAST AND PUSH THE RIDGE EAST. DUE TO THE
SOUTHERLY POSITION OF THE LOW, THE AIR MASS WILL BE ON THE WARMER
SIDE. THAT WILL SUPPORT THE CONTINUATION OF A GRADUAL WARMING EACH
DAY INTO THE MIDDLE OF NEXT WEEK. BY TUESDAY SOME VALLEY LOCATIONS
ARE EXPECTED TO EXPERIENCE ABOVE AVERAGE TEMPERATURES WITH MORE
WIDESPREAD ABOVE AVERAGE TEMPERATURES WEST OF THE MOUNTAINS ON
WEDNESDAY AND THURSDAY. THE MOUNTAINS AND DESERTS ARE EXPECTED TO
REMAIN NEAR OR SLIGHTLY BELOW AVERAGE FOR THIS TIME OF YEAR.
TEMPERATURES IN THE MOUNTAINS AND DESERTS WILL BE MODERATED BY AN
INFLUX OF MONSOONAL MOISTURE FOR THE MIDDLE TO END OF NEXT WEEK. THE
MOISTURE LOOKS TO PEAK ON FRIDAY. NBM DAILY CHANCES FOR MEASURABLE
RAINFALL FOR BIG BEAR INCREASING TO 10 PERCENT ON WEDNESDAY, 19
PERCENT ON THURSDAY, AND 25 PERCENT ON FRIDAY.
A MARINE LAYER NEAR 3000 FEET DEEP TODAY WILL GRADUALLY DECREASE IN
DEPTH FOR FRIDAY AND SATURDAY. COASTAL LOW CLOUDS WILL EXTEND INTO
PORTIONS OF THE INLAND VALLEYS FOR LATE TONIGHT INTO FRIDAY MORNING,
AND INTO THE WESTERN VALLEYS FOR LATE FRIDAY NIGHT INTO SATURDAY
MORNING. FOR NEXT WEEK, THE MARINE LAYER WILL BECOME SHALLOWER WITH
NIGHT AND MORNING COASTAL LOW CLOUDS EXTENDING INTO THE FAR WESTERN
VALLEYS AT TIMES LATE EACH NIGHT.
AVIATION
120300Z...COAST/VALLEYS...PATCHY LOW CLOUDS BASED 1500-2000 FT MSL
ARE FORMING ALONG THE SD COUNTY COAST, PUSHING TO INLAND THROUGH 06Z
THEN BUILDING INTO ORANGE COUNTY BETWEEN 07-10Z. BASES COULD RISE TO
2000-2500 FT MSL IN SPOTS THROUGHOUT THE NIGHT. SCT-BKN CLOUD
COVERAGE WILL BUILD INTO PARTS OF THE INLAND EMPIRE, WITH THE
GREATEST COVERAGE LIKELY BETWEEN 11-15Z. CLOUDS SCATTER TO THE COAST
17-19Z FRI, THEN REDEVELOP AND SPREAD INLAND AGAIN BETWEEN 01-03Z
SAT.
MOUNTAINS/DESERTS...BREEZY WESTERLY WINDS OF 20-25 KTS WITH GUSTS UP
TO 40 KTS THROUGH 10Z FRIDAY MORNING IN THE MOUNTAIN PASSES AND INTO
ADJACENT DESERTS, CAUSING ISOLATED POCKETS OF LLWS AND UP/DOWNDRAFTS
IN LEE OF MOUNTAINS. OTHERWISE, VFR CONDITIONS EXPECTED.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH TUESDAY.
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...SS
AVIATION/MARINE...WESTERINK
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