112
FXUS66 KSGX 191748
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
1048 AM PDT MON OCT 19 2026
SYNOPSIS
ONSHORE FLOW WILL BEGIN TO SPREAD COOLING INLAND TODAY WITH A
RETURN OF COASTAL LOW CLOUDS AND FOG MORE LIKELY FOR TONIGHT INTO
TUESDAY MORNING. A LOW PRESSURE SYSTEM FROM THE NORTH IS EXPECTED
TO BRING GREATER COOLING FOR WEDNESDAY AND THURSDAY ALONG WITH
SHOWERS AND A CHANCE OF THUNDERSTORMS, MOST LIKELY FOR WEDNESDAY
NIGHT THROUGH THURSDAY AFTERNOON. THEN WARMER AND DRIER FOR NEXT
WEEKEND.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
..UPDATED AVIATION DISCUSSION
SHORT TERM (TODAY THROUGH WEDNESDAY)
HIGH TEMPERATURES FOR TODAY WILL BE SLIGHTLY WARMER FOR THE
MOUNTAINS, DESERTS, AND INLAND VALLEYS WITH COASTAL AREAS INTO THE
WESTERN VALLEYS A FEW DEGREES COOLER. GREATER COOLING WILL SPREAD
INLAND ON TUESDAY AND WEDNESDAY WITH WEDNESDAY HIGH TEMPERATURES
NEAR AVERAGE AT THE COAST TO 5 TO 10 DEGREES BELOW AVERAGE FOR THE
MOUNTAINS. HIGH TEMPERATURES ON WEDNESDAY WILL BE MOSTLY IN THE
70S FOR THE COAST AND VALLEYS AND IN THE MID 80S FOR THE LOWER
DESERTS.
SATELLITE IMAGERY SHOWS SOME PATCHY LOW CLOUDS AND FOG OFF THE
ORANGE COUNTY COAST BENEATH A STRONG AND SHALLOW MARINE
INVERSION. THERE COULD BE SOME VERY PATCHY DENSE FOG NEAR THE
ORANGE COUNTY COAST EARLY THIS MORNING. THE MORE LIKELY TIME FOR
A RETURN OF GREATER COVERAGE OF LOW CLOUDS AND LOCALLY DENSE FOG
FOR THE COASTAL WATERS INTO COASTAL AREAS IS FOR TONIGHT INTO
TUESDAY MORNING. DEEPENING OF THE MARINE LAYER AND GREATER INLAND
SPREAD OF COASTAL LOW CLOUDS INTO PORTIONS OF THE VALLEYS IS
EXPECTED FOR TUESDAY NIGHT INTO WEDNESDAY MORNING.
A CLOSED LOW PRESSURE SYSTEM CENTERED TO THE WEST OF POINT
CONCEPTION ON LATE TUESDAY WILL BEGIN TO MOVE SLOWLY TOWARD THE
EAST ON WEDNESDAY. THIS WILL DRAW SUBTROPICAL MOISTURE AND SHOWERS
NORTHWARD AHEAD OF THIS LOW PRESSURE SYSTEM ON WEDNESDAY. SHOWERS
WILL BEGIN TO MOVE INTO PORTIONS OF SOUTHWESTERN CALIFORNIA DURING
THE DAY ON WEDNESDAY.
LONG TERM (WEDNESDAY NIGHT THROUGH SUNDAY)
THAT LOW PRESSURE SYSTEM WILL MOVE SLOWLY EASTWARD AND INLAND INTO
SOUTHERN CALIFORNIA FOR WEDNESDAY NIGHT AND THURSDAY. THIS WILL
BRING SHOWERS AND A CHANCE OF THUNDERSTORMS TO SOUTHWESTERN
CALIFORNIA, MOST LIKELY FOR WEDNESDAY NIGHT THROUGH THURSDAY
AFTERNOON.
THE ECMWF EXTREME FORECAST INDEX HAS RAINFALL ACROSS COASTAL
PORTIONS OF ORANGE AND LOS ANGELES COUNTIES IN THE 80TH TO 90TH
PERCENTILE. COLD AIR ALOFT WITH THE LOW PRESSURE SYSTEM PASSING
OVER NEAR RECORD WARM WATER OFF THE COAST WILL INCREASE THE
INSTABILITY WITH THE ECMWF EXTREME FORECAST INDEX HAVING CAPE OVER
THE COASTAL WATERS INTO COASTAL WATERS IN THE 80TH TO 90TH
PERCENTILE AND LOCALLY IN THE 90TH TO 95TH PERCENTILE.
FOR ORANGE AND SOUTHWESTERN SAN BERNARDINO COUNTIES, RAINFALL
COULD RANGE FROM AROUND 1 INCH FOR THE ORANGE COUNTY COASTAL PLAIN
TO AROUND 1.5 INCHES ON THE COASTAL SLOPES OF THE MOUNTAINS
WITH AMOUNTS DECREASING FROM NORTH TO SOUTH ACROSS SAN DIEGO
COUNTY.
HIGH TEMPERATURES WILL BE COOLEST ON THURSDAY, AS MUCH AS 15 TO 20
DEGREES BELOW AVERAGE FOR THE MOUNTAINS. HIGH TEMPERATURES ON
THURSDAY WILL BE MOSTLY IN THE 60S TO AROUND 70 FOR THE COAST AND
VALLEYS AND MOSTLY IN THE 40S AND 50S FOR THE MOUNTAINS.
DRIER AND WARMER WEATHER IS EXPECTED FOR NEXT WEEKEND, BUT WITH
GROWING SPREAD IN JUST HOW MUCH WARMING FOR SATURDAY THROUGH
MONDAY. HEATRISK IS FORECAST TO REMAIN BELOW MODERATE FOR NEXT
WEEKEND.
AVIATION
191700Z...COAST...VFR AND SKC THROUGH LATE THIS EVENING. LOW CLOUDS
AND FOG MUCH MORE LIKELY TO FORM AFTER 05Z TUESDAY, BECOMING MORE
WIDESPREAD BY 12Z TUESDAY. BASES WOULD BE AROUND 500-800 FEET MSL
WITH VIS 1-6SM ON MESAS AND HIGHER COASTAL TERRAIN INITIALLY, WITH
BASES AND VIS LIKELY RISING SLIGHTLY TUE MORNING BEFORE CLOUDS
SCATTER OUT 16-17Z.
OTHERWISE...MOSTLY CLEAR AND VFR CONDITIONS EXCEPT FOR SCT-BKN
CUMULUS BASED AROUND 10 KFT OVER MOUNTAINS 19-00Z.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH WEDNESDAY
MORNING. A STORM SYSTEM MOVES INTO THE REGION LATER WEDNESDAY
THROUGH THURSDAY, BRINGING GUSTS AT OR EXCEEDING 20 KNOTS AND
ASSOCIATED CHOPPY SEAS, ALONG WITH A 10-15% CHANCE OF TSRA.
BEACHES
SOUTHERLY SWELLS WILL CONTINUE TO BRING SURF OF 3 TO 6 FEET WITH
LOCAL SETS TO 7 FEET, HIGHEST AT SOUTH AND SOUTHWEST-FACING BEACHES
THROUGH TUESDAY. THIS WILL BRING HAZARDOUS SWIMMING CONDITIONS FOR
MOST. WHILE SURF AND RIP CURRENTS WILL BE ELEVATED, DAILY HIGH TIDES
WILL NOT BE PARTICULARLY HIGH, AND THE THREAT OF COASTAL FLOODING IS
MINIMAL. FURTHER DETAILS CAN BE FOUND IN THE BEACH HAZARDS STATEMENT.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...BEACH HAZARDS STATEMENT THROUGH TUESDAY EVENING FOR ORANGE
COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.
PZ...NONE.
PUBLIC...17
AVIATION/MARINE/BEACHES...CSP
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