174
FXUS66 KSGX 112018
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
118 PM PDT THU SEP 11 2025
SYNOPSIS
GRADUAL WARMING TREND 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
MONSOONAL 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...
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
112000Z...COAST/VALLEYS...LOW CLOUD BASES AROUND 2000-2500 FT MSL
WILL BEGIN TO REFORM IN WESTERN SAN DIEGO COUNTY AROUND 23-01Z, AND
THEN FILL INTO ORANGE COUNTY AND THE INLAND AREAS AFTER 04Z. THERE
WAS ENOUGH CONFIDENCE FOR LOW CEILINGS IN THE INLAND EMPIRE TO
INCLUDE A TEMPO GROUP FOR KONT TO SEE LOW CLOUD BASES AROUND 2000 FT
MSL FROM 12-16Z. FULL CLOUD COVERAGE OF THE COASTAL BASIN IS NOT
EXPECTED. CLOUDS WILL SLOWLY BEGIN TO DIMINISH AROUND 15Z BEGINNING
IN INLAND AREAS AND SLOWLY RETREATING FROM THE COASTAL AREAS BY 20Z
FRIDAY AFTERNOON.
MOUNTAINS/DESERTS...VFR CONDITIONS PREVAIL THROUGH TONIGHT. BREEZY
WESTERLY WINDS OF 20-25 KTS WITH GUSTS UP TO 40 KTS 21-10Z TODAY
THROUGH FRIDAY MORNING IN THE MOUNTAIN PASSES AND INTO ADJACENT
DESERTS, CAUSING ISOLATED POCKETS OF LLWS AND UP/DOWNDRAFTS IN LEE
OF MOUNTAINS.
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...CO
AVIATION/MARINE...VILLAFANE
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