814
FXUS66 KSGX 181109
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
309 AM PST THU DEC 18 2025
SYNOPSIS
TODAY WILL BE MUCH WARMER FOR THE COAST AND VALLEYS WITH HIGH
TEMPERATURES FOR SOME INLAND AREAS AS MUCH AS 15 TO 25 DEGREES
ABOVE AVERAGE. ONSHORE FLOW WILL SPREAD COOLING INLAND FOR FRIDAY
AND SATURDAY WITH NOT MUCH CHANGE FOR SUNDAY AND MONDAY. A LOW
PRESSURE SYSTEM FROM THE WEST WILL BRING INCREASING CHANCES FOR
RAIN BEGINNING TUESDAY WITH WIDESPREAD HEAVY RAINFALL BEGINNING ON
WEDNESDAY AND POSSIBLY CONTINUING AT TIMES INTO THE FINAL WEEKEND
IN DECEMBER.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHORT TERM (TODAY THROUGH SATURDAY)
AS EXPECTED, COVERAGE OF COASTAL LOW CLOUDS AND LOCALLY DENSE FOG
IS SUBSTANTIALLY LESS THAN 24 HOURS AGO. HIGHER RESOLUTION MODELS
SHOW PATCHES OF LOW CLOUDS AND DENSE FOG COULD EXTEND TO NEAR THE
COAST THROUGH SUNRISE, FOLLOWED BY CLEARING THROUGH THE MORNING AS
WEAK OFFSHORE FLOW DEVELOPS.
HIGH TEMPERATURES FOR TODAY WILL BE MUCH WARMER FOR THE COAST AND
AND VALLEYS, AS MUCH AS 8 TO 12 DEGREES WARMER THAN WEDNESDAY WITH
HIGH TEMPERATURES FOR SOME INLAND AREAS AS MUCH AS 15 TO 25
DEGREES ABOVE AVERAGE. HIGH TEMPERATURES FOR TODAY WILL RANGE FROM
AROUND 70 NEAR THE COAST TO THE UPPER 70S TO MID 80S FOR THE
VALLEYS AND FOR THE LOWER DESERTS. HIGH TEMPERATURE RECORDS FOR
TODAY ARE MOST LIKELY TO BE TIED OR BROKEN IN THE MOUNTAINS,
INLAND VALLEYS, AND LOWER DESERTS.
ONSHORE FLOW WILL BEGIN TO SPREAD COOLING INLAND ON FRIDAY WITH
HIGH TEMPERATURES FOR THE COAST, VALLEYS, AND COASTAL SLOPES OF
THE MOUNTAINS A FEW TO AROUND 5 DEGREES COOLER THAN TODAY. MOST
AREAS WILL BE A FEW TO AROUND 5 DEGREES COOLER ON SATURDAY, BUT
WITH HIGH TEMPERATURES STILL AS MUCH AS 12 TO 18 DEGREES ABOVE
AVERAGE FOR THE MOUNTAINS BELOW 5000 FEET AND FOR THE HIGH DESERT.
HIGH TEMPERATURES ON SATURDAY WILL RANGE FROM THE 60S NEAR THE
COAST TO THE 70S FOR THE VALLEYS WITH THE LOWER DESERTS AROUND 80.
SOME PATCHY LOW CLOUDS AND LOCALLY DENSE FOG COULD RETURN NEAR THE
COAST LATE TONIGHT INTO FRIDAY MORNING WITH MORE WIDESPREAD
COVERAGE OF LOW CLOUDS AND FOG FOR THE COASTAL WATERS AND COASTAL
AREAS EXPECTED FOR FRIDAY NIGHT INTO SATURDAY MORNING.
LONG TERM (SUNDAY THROUGH WEDNESDAY)
NOT MUCH CHANGE IN HIGH TEMPERATURES IS EXPECTED FOR SUNDAY AND
MONDAY WITH HIGH TEMPERATURES FOR INLAND AREAS REMAINING 10 TO 15
DEGREES ABOVE AVERAGE. NIGHT AND MORNING COASTAL LOW CLOUDS AND
FOG WILL SPREAD INTO THE FAR WESTERN VALLEYS BY MONDAY MORNING AS
THE MARINE LAYER DEEPENS SLIGHTLY.
FOR THE MIDDLE AND LATTER PART OF NEXT WEEK, A LOW PRESSURE
SYSTEM OFF THE WEST COAST WITH A MOISTURE FEED FROM AN ATMOSPHERIC
RIVER WILL BRING INCREASING CHANCES FOR RAIN BEGINNING NEXT
TUESDAY WITH WIDESPREAD HEAVY RAINFALL BEGINNING ON WEDNESDAY AND
POSSIBLY CONTINUING AT TIMES INTO THE FINAL WEEKEND IN DECEMBER.
FOR WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT FOR LYTLE CREEK ON
THE COASTAL SLOPES OF THE EASTERN SAN GABRIEL MOUNTAINS, THE
CHANCE FOR 3 INCHES OR MORE OF RAINFALL HAS INCREASED TO 55
PERCENT WITH A 19 PERCENT CHANCE FOR 5 INCHES OR MORE AND A 5
PERCENT CHANCE FOR 6 INCHES OR MORE. FOR WEDNESDAY MORNING THROUGH
THURSDAY NIGHT, THERE IS A 7 PERCENT CHANCE FOR 8 INCHES OR MORE
OF RAINFALL AT LYTLE CREEK.
MOST OF THE PRECIPITATION ACROSS SOUTHWESTERN CALIFORNIA THROUGH
CHRISTMAS THURSDAY IS EXPECTED TO FALL AS RAIN WITH SNOW LEVELS
REMAINING ABOVE 7000 FEET.
AVIATION
181030Z...COAST...PATCHY AND INTERMITTENT LOW CLOUDS AND FOG WILL
CONTINUE THIS MORNING. BASES 300-500 FEET MSL WITH VIS 3-5SM EXCEPT
0-2SM IN BR/FG. ANY BRIEF, ISOLATED IFR/LIFR CONDITIONS WILL CLEAR
OUT BY 16Z, BUT WITH AREAS OF VIS 5-6SM IN HZ. AREAS OF LOW CLOUDS
AND FOG TO REDEVELOP ALONG THE COAST AFTER 01Z, BUT NOT UNIFORMLY,
AND NOT TO EXTEND VERY FAR INLAND OVERNIGHT. ANY CIGS WOULD BE 300-
700 FEET MSL AND VIS 1-5SM.
OTHERWISE...VFR CONDITIONS TODAY AND TONIGHT WITH THIN HIGH CLOUDS.
MARINE
PATCHY FOG COULD REDUCE VISIBILITY TO 1 SM THIS MORNING. OTHERWISE,
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH MONDAY.
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...17
AVIATION/MARINE...MM
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