137
FXUS66 KSGX 200933
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
133 AM PST THU FEB 20 2025
SYNOPSIS
WARMER DAYS WILL CONTINUE INTO THE WEEKEND WITH WEAK SANTA ANA
WINDS MOVING INTO THE REGION TODAY AND FRIDAY. THIS IS LEADING TO
A SHALLOWER MARINE LAYER THIS MORNING INTO FRIDAY, WHERE PATCHY
LOW CLOUDS WILL BE NEAR THE COAST EACH MORNING. HIGH PRESSURE
ALOFT BECOMES STRONGER BY THE EARLY AND MIDDLE PART OF NEXT WEEK,
LEADING TO EVEN WARMER CONDITIONS WITH HIGHS 10 TO 20 DEGREES
ABOVE NORMAL.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SURFACE LEVEL WINDS ARE BEGINNING TO TURN WEAKLY OFFSHORE THIS
MORNING FOR INLAND AREAS AS LOW CLOUDS SUBTLY INCREASE IN COVERAGE
NEAR THE BEACHES. CLOUDS WILL CONTINUE TO BE INTERMITTENT NEAR THE
COAST, BUT WHEREVER CLOUDS DO FORM, PATCHY FOG CAN BE EXPECTED
THROUGH MID-MORNING. SANTA ANA WINDS FROM THE NORTH AND NORTHEAST
WILL INCREASE INTO THE AFTERNOON. CONFIDENCE IS MODERATE TO HIGH
IN SEEING WINDS OVER 35 MPH BELOW PASSES/CANYONS ACROSS PARTS OF
INLAND ORANGE COUNTY AND THE INLAND EMPIRE BY THIS AFTERNOON.
WINDS WILL STILL BE OFFSHORE TONIGHT, WEAKENING SLIGHTLY, THEN
INCREASING BY FRIDAY AFTERNOON, THOUGH NOT AS STRONG AS TODAY'S
WINDS. AS THE OFFSHORE WINDS MOVE OVER OUR REGION, DOWNSLOPE
WARMING WILL OCCUR, LEADING TO HIGHER TEMPERATURES ACROSS THE
LOWER ELEVATIONS. HIGHS WERE RAISED A FEW DEGREES FROM NBM TO
ACCOUNT FOR THIS LARGELY ABOVE AVERAGE WARMING. CONFIDENCE OF
INLAND VALLEYS WEST OF THE MOUNTAINS REACHING 80 DEGREES IS LOWER
TODAY BUT HIGHER BY FRIDAY AFTERNOON. AS IS TYPICAL WITH THIS WIND
PATTERN, PASSES AND CANYONS WHERE WINDS BLOW THROUGH THE NIGHT
WILL SEE WARMER LOW TEMPS THAN THOSE IN WIND-SHELTERED VALLEYS.
WINDS TURN WEAKER BY THE WEEKEND AND INTO NEXT WEEK AS HIGH
PRESSURE MAINTAINS ITS PRESENCE OVER THE AREA, CONTINUING THE
WARM AND DRY WEATHER PATTERN. MODELS SUGGEST THIS RIDGE OF HIGH
PRESSURE AMPLIFYING OVER THE WESTERN U.S. BY TUESDAY AND
WEDNESDAY. THIS WOULD BRING FURTHER WARMING TO THE REGION WITH
HIGHS POSSIBLY REACHING OVER 90 DEGREES ACROSS THE COACHELLA
VALLEY AND OVER 85 DEGREES FOR SOME VALLEYS WEST OF THE MOUNTAINS.
THIS WARMTH LOOKS TO BE SHORT-LIVED AS MODELS INDICATE AN AREA OF
LOW PRESSURE EXPECTED TO MOVE SOMEWHERE IN OUR VICINITY FROM OFF
THE COAST, WHICH WILL AID TO BRING IN COOLER WEATHER BY THE END
OF NEXT WEEK.
AVIATION
200930Z...COAST...PATCHY LOW CLOUDS AND FOG HAVE DEVELOPED ALONG THE
IMMEDIATE COAST, BASED AT 200-600 FT MSL. WHILE THESE WILL REMAIN
SOMEWHAT PATCHY, LOW CLOUDS WILL CONTINUE TO DEVELOP WITHIN 5 MILES
OF THE COAST, MOVING INTO MOST COASTAL SITES BY 13Z THIS MORNING.
THESE WILL BRING VIS REDUCTIONS 1-4 SM FOR COASTAL AREAS AND 0-2 SM
FOR COASTAL MESAS/HIGHLANDS. THERE IS A 20-30% CHANCE FOR VIS LOWER
THAN 1 SM FOR COASTAL SITES 13-16Z THIS MORNING. LOW CLOUDS/FG
RETREAT TO BEACHES 15-17Z IN MOST AREAS, THOUGH PATCHES IN NORTHERN
ORANGE COUNTY MAY LINGER THROUGH 18Z. AREAS OF FOG COULD REMAIN
ALONG THE IMMEDIATE BEACHES THROUGH THE EARLY AFTERNOON. MOSTLY
CLEAR SKIES FOLLOWING EXCEPT FOR OCCASIONAL FEW-SCT HIGH CLOUDS
THROUGH LATE THIS EVENING. LOW CLOUDS LOOK TO REDEVELOP AFTER 08-09Z
FRI, BUT WILL BE MORE ISOLATED, WITH THE GREATEST CHANCES FOR
IMPACTS (60% CHANCE) IN SOUTHERN SAN DIEGO COUNTY 09-14Z FRI. BASES
AND VIS WOULD BE SIMILAR TO THIS MORNING.
VALLEYS/MOUNTAINS/DESERTS...FEW-SCT HIGH CLOUDS ABOVE 25,000 FT MSL
AND VFR CONDITIONS TODAY AND TONIGHT. NORTH-NORTHEAST TO EASTERLY
WINDS WILL STRENGTHEN OVER MOUNTAINS AND FOOTHILLS/IN DESERTS AND
PARTS OF THE INLAND EMPIRE (GENERALLY AREAS BELOW/SOUTH OF THE CAJON
PASS) EARLY THURSDAY AFTERNOON, REMAINING INTERMITTENTLY GUSTY
THROUGH THE PERIOD. GUSTS TO 25-40 KTS AND MOD UP/DOWNDRAFTS NEAR
AND OVER MOUNTAINS.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE ANTICIPATED 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...APR
AVIATION/MARINE...CSP
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