333
FXUS66 KSGX 210954
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
254 AM PDT MON APR 21 2025
SYNOPSIS
DRY WEATHER WILL CONTINUE THIS WEEK WITH GUSTY SEA BREEZE WINDS
IN THE MOUNTAINS AND DESERTS EACH LATE AFTERNOON THROUGH LATE
EVENING. THE MOUNTAINS AND DESERTS WILL WARM SLOWLY FOR TODAY AND
TUESDAY WHILE THE COAST AND VALLEYS COOL SLIGHTLY. COOLING WILL
THEN SPREAD INLAND THROUGH FRIDAY AND SATURDAY AS THE MARINE LAYER
DEEPENS WITH SATURDAY HIGH TEMPERATURES A FEW DEGREES BELOW
AVERAGE TO 5 TO 10 DEGREES BELOW AVERAGE FOR THE MOUNTAINS. THIS
WILL BE FOLLOWED BY A WARMING TREND INTO EARLY NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHORT TERM (TODAY THROUGH WEDNESDAY)
ONSHORE FLOW WILL SLOWLY STRENGTHEN THROUGH WEDNESDAY WITH A WEAK
LOW PRESSURE SYSTEM OVER CALIFORNIA. THE DESERTS INTO THE
MOUNTAINS WILL CONTINUE TO WARM TODAY WITH SLIGHT ADDITIONAL
WARMING ON TUESDAY. THE COAST AND VALLEYS WILL COOL SLOWLY FOR
TODAY AND TUESDAY WITH THE COOLING SPREADING INLAND ON WEDNESDAY.
A MARINE LAYER AROUND 1500 FEET DEEP WILL BEGIN TO DEEPEN FOR
TUESDAY NIGHT INTO WEDNESDAY.
SATELLITE IMAGERY SHOWS WIDESPREAD LOW CLOUDS OVER THE EASTERN
PACIFIC WITH PATCHIER COVERAGE FROM THE OFFSHORE ISLANDS TO NEAR
THE COAST WITH A FLOW OF HIGH CLOUDS ABOVE 300 MB ACROSS THE
AREA. COVERAGE OF LOW CLOUDS MAY INCREASE SOME FOR COASTAL AREAS
PAST SUNRISE AND MAY EXTEND LOCALLY INTO THE FAR WESTERN VALLEYS.
GREATER COVERAGE IS EXPECTED FOR TONIGHT INTO TUESDAY MORNING FROM
THE COASTAL WATERS INLAND INTO THE WESTERN VALLEYS WITH GREATER
SPREAD INTO THE VALLEYS FOR TUESDAY NIGHT INTO WEDNESDAY MORNING.
LONG TERM (THURSDAY THROUGH SUNDAY)
LOW PRESSURE WILL CONTINUE TO STRENGTHEN NEAR THE CALIFORNIA COAST
INTO FRIDAY AND POSSIBLY INTO SATURDAY. THE MARINE LAYER WILL
CONTINUE TO DEEPEN WITH COASTAL LOW CLOUDS EXTENDING WELL INLAND
AND ONTO THE COASTAL SLOPES OF THE MOUNTAINS. HIGH TEMPERATURES
WILL CONTINUE TO COOL WITH HIGH TEMPERATURES FOR FRIDAY AND
SATURDAY A FEW DEGREES BELOW AVERAGE NEAR THE COAST TO 5 TO 10
DEGREES BELOW AVERAGE FOR THE MOUNTAINS. HIGH TEMPERATURES ON
FRIDAY AND SATURDAY ARE EXPECTED TO RANGE FROM THE LOWER 60S NEAR
THE COAST TO THE MID 60S TO LOWER 70S FOR THE INLAND EMPIRE WITH
THE LOWER DESERTS IN THE LOWER TO MID 80S. FOR SUNDAY INTO EARLY
NEXT WEEK, HIGH PRESSURE WILL BEGIN TO STRENGTHEN OFF THE WEST
COAST WITH WARMING FOR SOUTHERN CALIFORNIA.
AVIATION
210930Z....COASTS/VALLEYS...LIKELY INHIBITED BY SCT-BKN CIRRUS
CLOUDS, LOW CLOUDS HAVE BEEN STRUGGLING TO FILL IN AS PREVIOUSLY
EXPECTED, REMAINING QUITE PATCHY AND LARGELY OFFSHORE AT THIS HOUR.
STILL, THE EXPECTATION IS THE CLOUDS WILL EVENTUALLY FILL IN AND
PUSH ASHORE, WITH ABOUT 10 MILES OF INLAND EXTENT. THE TIMING OF THE
BEST CHANCE FOR CLOUDS/CIGS IS 12Z-17Z THIS MORNING. CLOUD BASES
WOULD BE GENERALLY 1000-1500FT MSL WITH ANY VIS RESTRICTIONS TO 2-4
SM LIMITED TO COASTAL MESAS AND LOCALLY WITHIN INLAND VALLEYS. ANY
CLOUDS THAT FILL IN OVER LAND WILL CLEAR BACK OUT BY 17-18Z. LOW
CLOUDS LOOK TO REBUILD AGAIN BETWEEN 03-06Z TUESDAY WITH SIMILAR
BASES. BETTER CONFIDENCE IN THESE CLOUDS THAN THIS MORNING'S, WITH
LESS CIRRUS EXPECTED AND LIKELY A FURTHER INLAND EXTENT OF THE
MARINE LAYER INTO INLAND VALLEYS.
MOUNTAINS/DESERTS...SCT HIGH CLOUDS OVERNIGHT, LESS WIDESPREAD ON
MONDAY WITH UNRESTRICTED VIS THROUGH THE PERIOD.
MARINE
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...MUNYAN
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