891
FXUS66 KSGX 240358
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
858 PM PDT WED APR 23 2025
SYNOPSIS
A COOLING TREND THROUGH SATURDAY, WITH HIGH TEMPERATURES 10 TO 15
DEGREES BELOW AVERAGE FOR INLAND AREAS TO AS MUCH AS 20 DEGREES
BELOW AVERAGE FOR THE HIGHER ELEVATIONS OF THE MOUNTAINS BY THE
WEEKEND. THE MARINE LAYER WILL DEEPEN WITH NIGHT AND MORNING
COASTAL LOW CLOUDS AND FOG EXTENDING ONTO THE LOWER COASTAL SLOPES
OF THE MOUNTAINS FOR TODAY AND THURSDAY, THEN FARTHER ONTO THE
COASTAL MOUNTAIN SLOPES FOR FRIDAY AND SATURDAY. THERE WILL BE
STRONGER ONSHORE FLOW WITH GUSTY SOUTHWEST TO WEST WINDS FOR THE
MOUNTAINS AND DESERTS EACH LATE AFTERNOON AND EVENING THROUGH
SATURDAY. THERE IS ALSO A SLIGHT CHANCE FOR MOSTLY LIGHT SHOWERS
FOR LATE FRIDAY NIGHT INTO SATURDAY EVENING. THEN DRY WITH A
WARMING TREND FOR SUNDAY THROUGH TUESDAY.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
UPDATE: THE MODELS HAVE BEEN RATHER CONSISTENT WITH THE TIMING OF A
SHORTWAVE MOVING OVER THE REGION THROUGH THE EARLY PART THE WEEKEND,
WHICH WILL BRING A CHANCE OF LIGHT RAIN AND/OR DRIZZLE TO PORTIONS
OF THE COASTAL AND INLAND AREAS, AS WELL AS PROVIDE STRONG AND GUSTY
WINDS FOR THE MOUNTAINS AND DESERTS, PARTICULARITY THOSE
LOCATIONS MOST PRONE TO GAP FLOW WINDS, SUCH AS THE PASSES AND
COACHELLA VALLEY. THE HIGH RES GUIDANCE REFLECTS THAT THE BEST
CHANCE OF ANY MEASURABLE PRECIPITATION WILL BE DURING THE
AFTERNOON ON SATURDAY, WITH GRADUAL CLEARING GOING INTO THE LATE
EVENING HOURS, AND THEN DRYING OUT BY SUNDAY. SATURDAY STILL
APPEARS TO BE THE COOLEST DAY, WITH HIGHS GENERALLY ANYWHERE
BETWEEN 10 TO 20 DEGREES BELOW THE SEASONAL AVERAGE FOR MOST
LOCATIONS. MODELS HAVE ALSO REMAINED CONSISTENT WITH SHOWING
SLIGHT RIDGING AND A WARMING TREND THROUGH THE MID PART OF NEXT
WEEK. ONSHORE FLOW WILL ALSO REMAIN PERSISTENT, AND KEEP THE
MARINE LAYER REDEVELOPMENT DURING THE OVERNIGHT HOURS CONTINUING
THROUGH THE MID PART OF NEXT WEEK AS WELL.
(PREVIOUS DISCUSSION SUBMITTED AT 139 PM):
SATELLITE SHOWS THAT EXTENSIVE CLOUD COVER REMAINS WITH SLOW
CLEARING FROM SOUTH TO NORTH. PARTS OF RIVERSIDE AND ORANGE COUNTIES
WILL STRUGGLE TO CLEAR TODAY, BUT CLOUDS SHOULD RETREAT TO THE COAST
BY THE LATE AFTERNOON. SUNNY SKIES AND INCREASING WINDS OUT OF THE
WEST OVER THE NEXT SEVERAL HOURS, CALMING LATER TONGIHT. HEIGHTS
FALL THROUGH SATURDAY AS A TROUGH OFF THE COAST OF CANADA BECOMES A
CUTOFF LOW AND MOVES SOUTHWARD INTO CALIFORNIA. WITH THE FALLING
HEIGHTS, THE MARINE LAYER DEEPENS THE NEXT FEW MORNINGS, MAKING IT
FURTHER INLAND EACH DAY AND ALLOWING MORNING DRIZZLE TO OCCUR,
ESPECIALLY FOR THE COASTAL AREAS AND VALLEYS. TEMPERATURES ALSO
RESPOND, WITH HIGHS FALLING SUBSTANTIALLY BY FRIDAY AND SATURDAY,
GENERALLY 5-20 DEGREES BELOW NORMAL FOR THE END OF APRIL. GUSTY WEST
WINDS DEVELOP EACH AFTERNOON AND EVENING AS THE GRADIENT TIGHTENS
THIS WEEK, WITH GUSTS UP TO 40 MPH IN THE DESERTS AND MOUNTAINS AND
LOCALIZED AREAS OF GUSTS UP TO 55 MPH THROUGH THE MOUNTAIN PASSES,
PEAKING BOTH FRIDAY AND SATURDAY AFTERNOONS. SOME AREAS OF BLOWING
DUST WILL BE POSSIBLE, ESPECIALLY IN THE DESERTS.
THE LATEST MODEL RUNS HAVE SLOWED THE PROGRESSION OF THE
AFOREMENTIONED LOW AND BROUGHT IT A SMIDGE FURTHER SOUTH ON
SATURDAY, INDICATING SLIGHTLY HIGHER PRECIPITATION CHANCES THAN
PREVIOUS RUNS, NOW AROUND 20-25% FOR THE MOUNTAINS. WHILE POPS
HAVE INCREASED, QPF UNFORTUNATELY REMAINS FAIRLY LOW WITH LIMITED
MOISTURE AND ENERGY TO TAP IN TO. RIGHT NOW THE BEST CHANCES FOR
ACCUMULATING RAINFALL WILL BE FOR THE AREAS FURTHER NORTH,
ESPECIALLY THE HIGHER TERRAIN, WHERE UP TO 0.10-0.15" IS POSSIBLE
THROUGH SATURDAY NIGHT.
AS THE LOW MOVES UP INTO NEVADA ON SUNDAY, HIGHS WARM A FEW DEGREES
BUT WILL REMAIN WELL BELOW NORMAL. BY MONDAY, WEAK UPPER LEVEL
RIDGING STARTS TO BUILD IN, WITH TEMPERATURES QUICKLY WARMING
THROUGH MID WEEK AND HIGHS RETURN TO NEAR OR SLIGHTLY ABOVE NORMAL
BY TUESDAY.
AVIATION
240330Z....COASTS/VALLEYS/COASTAL MOUNTAIN SLOPES...CLOUDS CONTINUE
TO SPREAD INLAND THIS EVENING AND TONIGHT BASED AT 2000-3000 FT MSL,
AND WILL FILL THE COASTAL BASIN BY EARLY THURSDAY MORNING, BRINGING
PATCHY DZ. CLOUDS CLEARING AGAIN 16-19Z FRIDAY, THOUGH LOCALLY BKN
NEAR THE COAST INTO THE AFTERNOON. CLOUDS 2500-3500 FT MSL SPREADING
INLAND AGAIN TO A SIMILAR INLAND EXTANT AFTER 02Z FRI.
OTHERWISE...MOSTLY CLEAR THROUGH WEDNESDAY.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH SUNDAY.
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...ZUBER
AVIATION/MARINE...CSP
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page