495
FXUS66 KSGX 201759
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
1059 AM PDT MON APR 20 2026
SYNOPSIS
ONSHORE FLOW WILL BEGIN TO STRENGTHEN TODAY WITH HIGH TEMPERATURES
FOR THE COAST AND VALLEYS COOLING A FEW DEGREES. A LOW PRESSURE
SYSTEM MOVING INLAND THROUGH CALIFORNIA WILL BRING MORE COOLING
FOR TUESDAY AND WEDNESDAY WITH SOUTHWEST TO WEST WINDS FOR THE
MOUNTAINS AND DESERTS STRONGEST FOR TUESDAY AFTERNOON AND NIGHT
WITH GUSTS TO 40 TO 50 MPH AND ISOLATED GUSTS TO 65 MPH. THERE IS
ALSO A SLIGHT CHANCE FOR LIGHT SHOWERS FOR LATE TUESDAY AFTERNOON
THROUGH TUESDAY NIGHT. THURSDAY WILL BE WARMER FOLLOWED BY A
COOLING TREND THROUGH NEXT WEEKEND.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
..UPDATED MARINE/AVIATION SECTIONS
SHORT TERM (TODAY THROUGH WEDNESDAY)
A CLOSED LOW PRESSURE SYSTEM OFF THE WEST COAST WILL MOVE INTO AND
THROUGH CALIFORNIA ON TUESDAY AND WEDNESDAY. ONSHORE FLOW WILL
BEGIN TO STRENGTHEN TODAY WITH SOUTHWEST TO WEST WINDS FOR THE
MOUNTAINS AND DESERTS GUSTING TO 30 TO 40 MPH FOR THIS AFTERNOON
AND EVENING. COASTAL LOW CLOUDS WILL EXTEND INTO PORTIONS OF THE
INLAND VALLEYS THIS MORNING AND HIGH TEMPERATURES FOR THE COAST
AND VALLEYS WILL BE A FEW DEGREES COOLER THAN SUNDAY, BUT STILL A
FEW DEGREES ABOVE AVERAGE. HIGH TEMPERATURES FOR TODAY WILL RANGE
FROM THE UPPER 60S NEAR THE COAST TO THE MID 70S TO LOWER 80S FOR
THE INLAND EMPIRE WITH THE LOWER 90S FOR THE LOWER DESERTS.
THERE WILL BE ADDITIONAL STRENGTHENING OF THE ONSHORE FLOW ON
TUESDAY WITH MORE WIDESPREAD AND STRONGER SOUTHWEST TO WEST WINDS
FOR THE MOUNTAINS AND DESERTS FOR TUESDAY AFTERNOON AND NIGHT WITH
GUSTS TO 40 TO 50 MPH AND ISOLATED GUSTS TO AROUND 65 MPH. THE
WINDS WILL SUBSIDE SOME ON WEDNESDAY WITH GUSTS TO 35 TO 45 MPH
AND WITH ISOLATED GUSTS TO 55 MPH.
FOR TUESDAY AND AGAIN ON WEDNESDAY, THERE WILL BE SLIGHT COOLING
OF HIGH TEMPERATURES NEAR THE COAST TO 4 TO 8 DEGREES OF COOLING
FOR THE MOUNTAINS AND DESERTS. HIGH TEMPERATURES ON WEDNESDAY WILL
BE AROUND 5 DEGREES BELOW AVERAGE FOR INLAND AREAS WITH HIGH
TEMPERATURES ON WEDNESDAY MOSTLY IN THE MID 60S TO LOWER 70S FOR
THE COAST AND VALLEYS AND IN THE LOWER TO MID 80S FOR THE LOWER
DESERTS.
THERE IS A SLIGHT CHANCE FOR LIGHT SHOWERS FOR LATE TUESDAY
AFTERNOON THROUGH TUESDAY NIGHT AS A WEAKENING COLD FRONT MOVES
ACROSS SOUTHWESTERN CALIFORNIA. MODELS ARE NOW KEEPING THE 500 MB
564 DM HEIGHT JUST NORTH OF THE AREA AS THE LOW PRESSURE SYSTEM
MOVES INLAND WHICH WOULD USUALLY MEAN LITTLE OR NO MEASURABLE
PRECIPITATION. THE MOST LIKELY LOCATION TO RECEIVE MEASURABLE
PRECIPITATION IN SOUTHWESTERN CALIFORNIA WOULD BE THE SAN
BERNARDINO COUNTY MOUNTAINS.
LONG TERM (THURSDAY THROUGH SUNDAY)
THURSDAY WILL BE DRY WITH HIGH TEMPERATURES SLIGHTLY WARMER THAN
WEDNESDAY NEAR THE COAST TO AROUND 5 DEGREES WARMER INLAND WITH
HIGH TEMPERATURES MOSTLY WITHIN A FEW DEGREES OF AVERAGE. HIGH
TEMPERATURES ON THURSDAY WILL RANGE FROM THE UPPER 60S NEAR THE
COAST TO THE MID TO UPPER 70S FOR THE INLAND EMPIRE WITH THE LOWER
DESERTS IN THE UPPER 80S TO AROUND 90.
FOR FRIDAY AND SATURDAY, A LOW PRESSURE SYSTEM OFF THE CALIFORNIA
COAST WILL BRING SLIGHT COOLING OF HIGH TEMPERATURES ON FRIDAY
WITH ADDITIONAL SLIGHT COOLING ON SATURDAY NEAR THE COAST TO
AROUND 5 DEGREES OF COOLING FOR INLAND AREAS.
A WEAK LOW PRESSURE SYSTEM COULD MOVE INTO SOUTHERN CALIFORNIA
SOME TIME AROUND NEXT WEEKEND BRINGING A SLIGHT CHANCE OF MOSTLY
LIGHT PRECIPITATION.
AVIATION
201800Z...COAST/VALLEYS...PATCHY LOW CLOUDS 1800-2500 FT MSL WILL
GRADUALLY DEVELOP AND EXPAND AFTER 05Z TONIGHT INTO TUESDAY, WITH
SIMILAR AREAL TO THIS MORNING AND NON-UNIFORM COVERAGE. CONDITIONS
WILL BOUNCE BETWEEN VFR AND MVFR MOST OF THE NIGHT. LOW CLOUDS CLEAR
14-17Z TUE MORNING.
MOUNTAINS/DESERTS...WEST TO WEST-SOUTHWEST WINDS WILL INCREASE AFTER
22Z TODAY, AND CONTINUE TO BE GUSTY TONIGHT INTO EARLY TUESDAY.
STRONGEST WINDS WILL GUST 25-35 KNOTS THROUGH MOUNTAIN GAPS, ALONG
THE DESERT SLOPES AND LOCALLY INTO DESERTS, PRODUCING MODERATE
UP/DOWNDRAFTS IN LEE OF MOUNTAINS.
OTHERWISE, MOSTLY CLEAR AND VFR CONDITIONS ARE EXPECTED TODAY AND
TONIGHT.
MARINE
WESTERLY WINDS WILL INCREASE WEDNESDAY, GENERATING CONDITIONS THAT
COULD BE HAZARDOUS FOR SMALL CRAFT WEDNESDAY INTO THURSDAY, WITH
GUSTS 20-25 KNOTS LIKELY. OTHERWISE, NO HAZARDOUS MARINE CONDITIONS
ARE EXPECTED THROUGH FRIDAY.
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...CSP
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