239
FXUS66 KSGX 130438
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
938 PM PDT TUE MAY 12 2026
SYNOPSIS
THROUGH WEDNESDAY, A WEAK LOW PRESSURE SYSTEM MOVING INTO SOUTHERN
CALIFORNIA WILL DEEPEN THE MARINE LAYER TO AROUND 3000 FEET WITH
NIGHT AND MORNING COASTAL LOW CLOUDS SPREADING FARTHER INTO THE
VALLEYS AND WITH SLOWER AFTERNOON CLEARING FOR SAN DIEGO COUNTY
COASTAL AREAS. IT WILL BE SLIGHTLY WARMER FOR THURSDAY AND FRIDAY
WITH THE MARINE LAYER DECREASING IN DEPTH, THEN SLIGHTLY COOLER
FOR THE WEEKEND.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
A WEAK UPPER LOW JUST OFFSHORE IS CONTRIBUTING TO STRENGTHENING
ONSHORE FLOW AND COOLER TEMPERATURES TODAY. SOUTH TO SOUTHEAST
WINDS WILL TURN OUT OF THE WEST THIS EVENING WITH GUSTS 25-45 MPH
FOR THE DESERTS AND DESERT SLOPES OF THE MOUNTAINS BOTH TODAY AND
WEDNESDAY AFTERNOON/EVENING. ON THE WEST SIDE OF THE MOUNTAINS,
VISIBLE SATELLITE INDICATES THAT MARINE LAYER CLOUDS HAVE HELD
STRONG OVER SAN DIEGO AND ORANGE COUNTIES THROUGH THIS MORNING.
ADDITIONALLY, TEMPERATURES THROUGH THE COASTAL BASIN ARE 15 TO 25
DEGREES COOLER THAN YESTERDAY AT THIS TIME. ALL SIGNS INDICATE
THAT OUR FIRST TRUE "MAY GRAY" DAY IS UPON US WITH COASTAL AREAS
EXPECTED TO STAY CLOUDY THROUGH THE AFTERNOON. LOW CLOUDS WILL
FILL MOST IF NOT ALL OF THE COASTAL BASIN TONIGHT WITH AREAS OF
DRIZZLE EXPECTED, ESPECIALLY NEAR THE COASTLINE IN THE EARLY
MORNING. THIS WILL LOCALLY CREATE MINOR VISIBILITY REDUCTIONS. AS
THE LOW PRESSURE MOVES OVERHEAD ON WEDNESDAY, A WEAKENED INVERSION
AND WEAKER ONSHORE FLOW SHOULD ALLOW FOR A MOSTLY SUNNY AFTERNOON.
DESPITE THE COOLING TREND, TEMPERATURES WILL STILL REACH THE LOW
100S TODAY ACROSS THE LOW DESERTS. EVEN WEDNESDAY, WHICH IS
EXPECTED TO BE THE COOLEST DAY, WILL BE AROUND 5-8 DEGREES ABOVE
NORMAL IN THE DESERTS WITH TEMPERATURES NEARING 100 AGAIN IN THE
COACHELLA VALLEY. MEANWHILE, TEMPERATURES WILL REMAIN NEAR TO
SLIGHTLY BELOW AVERAGE IN THE COASTAL BASIN THROUGH WEDNESDAY.
STARTING THURSDAY, A WEAK UPPER RIDGE WILL ATTEMPT TO NUDGE INTO
THE REGION. THIS WILL BUMP TEMPERATURES UP BY A FEW DEGREES FOR
ALL AREAS AND DECREASE THE DEPTH OF THE MARINE LAYER FOR BOTH
THURSDAY AND FRIDAY. THUS, TEMPERATURES IN THE LOW DESERTS ARE
EXPECTED TO REACH BACK INTO THE LOW 100S THURSDAY THROUGH
SATURDAY.
MODEL GUIDANCE BEGINS TO DIVERGE SLIGHTLY OVER THE WEEKEND, BUT
THE GENERAL CONSENSUS IS THAT AN UPPER LOW PRESSURE SYSTEM WILL
PASS TO THE NORTH SOMETIME LATE SATURDAY INTO EARLY SUNDAY. THIS
WILL HERALD INCREASED ONSHORE FLOW AND A COOLING TREND RESULTING
IN NEAR AVERAGE TEMPERATURES FOR ALL AREAS BY SUNDAY. A MINORITY
OF MODEL SOLUTIONS PRODUCE A FEW HUNDREDTHS OF AN INCH OF QPF FOR
COASTAL AREAS SUNDAY INTO EARLY MONDAY. HOWEVER, THIS LIKELY
REFLECTS THE POTENTIAL FOR MARINE LAYER DRIZZLE AND NOTHING MORE.
BEYOND THIS WEEKEND, GUIDANCE LEANS TOWARD A WARMING TREND AND
SLIGHTLY ABOVE NORMAL TEMPERATURES THROUGH MID NEXT WEEK.
AVIATION
130430Z...COAST/VALLEYS...PATCHY LOW CLOUDS WITH BASES MOSTLY 2000-
3000 FT MSL HAVE PARTIALLY CLEARED OUT OF SD COUNTY. CLOUD COVERAGE
WILL GRADUALLY FILL BACK INTO SD COUNTY AND THE INLAND EMPIRE.
MODERATE CONFIDENCE OF FULL CIG COVERAGE BY 09Z, HIGH CONFIDENCE OF
FULL COVERAGE BY 12Z. CLOUD BASES DROP SLIGHTLY THROUGHOUT THE NIGHT
TO 1500-2500 FT MSL AS CLOUD TOPS INCREASE MOSTLY ABOVE 4000 FT MSL,
YIELDING TO COASTAL -DZ MOST LIKELY 10-15Z WED. PATCHY VIS
REDUCTIONS 2-6SM FOR ELEVATED INLAND VALLEYS (ABOVE 1000 FT MSL) AND
0-3SM THROUGHOUT FOOTHILLS. BASES LIFT QUICKLY ABOVE 2000 FT MOST
LIKELY BY 15Z. SCATTER OUT 17-19Z INLAND WITH PATCHY BKN CLOUDS
LINGERING THROUGH THE AFTERNOON WITHIN 20 MILES OF THE COAST. MOST
BASES RISE TO ABOVE 3000 FT BY 18Z WHERE CLOUDS REMAIN. CLOUDS
WITH SIMILAR BASES (1500-2500 FT MSL) START TO DEVELOP AGAIN AFTER
00Z THU, PRIMARILY OVER SD COUNTY, EXPANDING FROM SOUTH TO NORTH.
ABOUT A 65% CIG COVERAGE OVER SD COUNTY BY 04Z, REACHING TO THE
FOOTHILLS.
MOUNTAINS/DESERTS...SCT HIGH CLOUDS AND VFR CONDITIONS INTO WED.
WEST WINDS WITH GUSTS 25-35 KT (LOCALLY TO 40 KTS) WEAKEN SLIGHTLY
WEDNESDAY MORNING, THEN STRENGTHEN AGAIN AFTER 20Z WED AFTERNOON.
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...KW
AVIATION/MARINE...WESTERINK
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page