383
FXUS66 KSGX 221640
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
940 AM PDT TUE APR 22 2025
SYNOPSIS
NIGHT AND MORNING LOW CLOUDS ARE EXPECTED EACH DAY AT THE COAST INTO
THE VALLEYS THROUGH THE WEEK. INCREASED SEA BREEZE WINDS ARE
EXPECTED EACH AFTERNOON AND EVENING FOR THE MOUNTAINS AND DESERTS,
STRONGER WESTERLY WINDS EXPECTED OVER THE WEEKEND. AREAS OF DRIZZLE
OR LIGHT RAIN ARE POSSIBLE WEST OF THE MOUNTAINS OVER THE WEEKEND. A
COOLING TREND WILL CONTINUE THROUGH THE END OF THE WEEK. GRADUAL
WARMING IS EXPECTED NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
LOW CLOUDS THIS MORNING MADE IT WELL INTO THE COASTAL BASIN. LOW
CLOUDS ARE STARTING TO CLEAR FROM THE VALLEYS AT 9 AM. IT'S LOOKING
LIKE LOW CLOUDS WILL CLEAR MOST AREAS THIS AFTERNOON, BUT WILL
QUICKLY MOVE BACK INLAND EARLY THIS EVENING. THE MARINE LAYER SHOULD
DEEPEN TONIGHT, LIKELY FILLING IN THE ENTIRE COASTAL BASIN AS A
TROUGH DEEPENS AND MOVES ACROSS THE PACIFIC NORTHWEST. IN ADDITION
TO WIDESPREAD CLOUD COVERAGE, WESTERLY WINDS WILL BE ELEVATED
WEDNESDAY AFTERNOON AND EVENING THROUGH PASSES AND LOCALLY INTO THE
DESERTS.
HIGHS TODAY WILL BE AROUND 4 TO 8 DEGREES ABOVE AVERAGE FOR THE
DESERTS INTO THE MOUNTAINS. HIGHS FOR THE COAST AND VALLEYS WILL BE
AS MUCH AS 5 DEGREES BELOW AVERAGE. HIGHS ON WEDNESDAY WILL BE
FAIRLY SIMILAR, WITH A FEW DEGREES OF COOLING IN THE MOUNTAINS AND
DESERTS. THE COOLING TREND WILL CONTINUE INTO THURSDAY, WITH HIGHS
IN THE DESERTS FALLING TO NEAR AVERAGE WITH THE WESTERN VALLEYS AND
INLAND ORANGE COUNTY AROUND 4 TO 8 DEGREES BELOW AVERAGE.
FRIDAY THROUGH THE WEEKEND A DEEPER LOW WILL MOVE ACROSS THE WEST
COAST. ENSEMBLE GUIDANCE IS IN BETTER AGREEMENT IN THE TRACK OF THE
LOW COMPARED TO 24-HOURS AGO. BY SATURDAY, THE MAJORITY OF ENSEMBLE
CLUSTERS INDICATE THE TROUGH WILL DIG INTO EITHER NORTHERN OR
CENTRAL CALIFORNIA. THAT WILL BRING A MORE SIGNIFICANT COOLING, WITH
THE POTENTIAL FOR STRONGER WINDS FOR THE MOUNTAINS AND DESERTS, AND
EVEN SOME LIGHT PRECIPITATION OR DRIZZLE TO AREAS WEST OF THE
MOUNTAINS. TIMING WISE, THE TROUGH IS EXPECTED TO PASS THROUGH
SOUTHERN CALIFORNIA SATURDAY EVENING INTO SUNDAY. NBM CHANCES FOR
WIND GUSTS REACHING OR EXCEEDING 45 MPH ON SATURDAY AFTERNOON AND
EVENING ARE AROUND 90 PERCENT FOR THE MOUNTAIN PASSES AND 50 TO 60
PERCENT FOR THE DESERTS. NBM CHANCES FOR MEASURABLE PRECIPITATION
(AT LEAST 0.01 INCHES) SATURDAY INTO SUNDAY ARE 5 TO 10 PERCENT FOR
THE COAST AND VALLEYS AND UP TO 25 PERCENT FOR THE COASTAL MOUNTAIN
SLOPES. NBM SEEMS TO BE ON THE MORE PESSIMISTIC SIDE OF THE
PROBABILITY OF PRECIPITATION WITH GFS AND ECMWF MOS HAVING CHANCES
FOR MEASURABLE PRECIPITATION HIGHER AND MORE CONSISTENT WITH THE
PATTERN, AROUND 15 PERCENT NEAR THE COAST TO 20 TO 30 PERCENT IN THE
MOUNTAINS.
DRY WITH A WARMING TREND FOR EARLY NEXT WEEK WITH TUESDAY HIGH
TEMPERATURES WARMING TO AROUND AVERAGE. THE MARINE LAYER WILL BECOME
SHALLOWER WITH COASTAL LOW CLOUDS NOT EXTENDING AS FAR INLAND.
AVIATION... 221530Z....COASTS/VALLEYS
LOW CLOUDS BASED 1500-2000
FEET MSL WITH TOPS TO 2500 FEET AND VIS REDUCTIONS 0-5 SM IN BR FOR
INLAND VALLEYS AND ON HIGHER COASTAL TERRAIN. THESE WILL LIFT AND
CLEAR THIS MORNING, SCATTERING OUT BY 17-18Z. LOW CLOUDS AT 1800-
2200 FEET MSL WILL PUSH ASHORE AFTER 03Z AND FILL THE COASTAL BASIN
OVERNIGHT, WITH VIS REDUCED FAR INLAND AND AGAINST COASTAL
FOOTHILLS. SCATTER OUT WEDNESDAY 17-19Z.
OTHERWISE...MOSTLY CLEAR THROUGH TUESDAY MORNING.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH SATURDAY.
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...MM
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