104
FXUS66 KSGX 181139
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
339 AM PST WED DEC 18 2024
SYNOPSIS
SANTA ANA WINDS WILL CONTINUE INTO THIS MORNING WITH GUSTS TO 45
MPH ALONG AND BELOW THE COASTAL SLOPES OF THE MOUNAINS WITH ISOLATED
GUSTS TO 55 MPH. THE WINDS WILL DIMINISH DURING THE AFTERNOON AND
EVENING. TODAY WITH BE THE WARMEST DAY FOR THE COAST AND VALLEYS
WITH GRADUAL COOLING SPREADING INLAND FOR THURSDAY THROUGH THE
WEEKEND. A WEAK COASTAL EDDY COULD BRING A RETURN OF PATCHY NIGHT
AND MORNING LOW CLOUDS AND FOG NEAR THE COAST FOR TONIGHT AND
THURSDAY NIGHT WITH AN INCREASE IN COVERAGE POSSIBLE FOR THE
WEEKEND. AROUND TUESDAY OF NEXT WEEK, A LOW PRESSURE SYSTEM
MOVING QUICKLY INLAND THROUGH CALIFORNIA COULD BRING STRONG GUSTY
WEST WINDS FOR THE MOUNTAINS AND DESERTS AND A CHANCE OF SHOWERS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHORT TERM (TODAY THROUGH FRIDAY)
AFTER PEAKING OVERNIGHT, GUSTY SANTA ANA WINDS WILL CONTINUE INTO
THIS MORNING WITH GUSTS TO 40 TO 50 MPH ALONG AND BELOW THE
COASTAL SLOPES OF THE MOUNTAINS WITH ISOLATED GUSTS TO 60 MPH. THE
WINDS WILL DIMINISH DURING THE AFTERNOON AND EVENING.
HIGH TEMPERATURES ARE EXPECTED TO WARM A FEW TO AROUND 5 DEGREES
FOR THE INLAND AREAS TODAY WITH THE COAST AND WESTERN VALLEYS
ANOTHER 5 TO 10 DEGREES WARMER THAN TUESDAY, REACHING THE LOWER TO
MID 80S FOR PORTIONS OF THE VALLEYS AND INLAND COASTAL AREAS, AS
MUCH AS 12 TO 18 DEGREES ABOVE AVERAGE.
A RETURN OF WEAK ONSHORE FLOW WILL BEGIN TO SPREAD COOLING SLOWLY
INLAND FOR THURSDAY AND FRIDAY WITH THE COAST AND WESTERN VALLEYS
COOLING A FEW TO AROUND 5 DEGREES ON THURSDAY AND ANOTHER FEW TO
AROUND 5 DEGREES OF COOLING FOR FRIDAY FOR MOST OF THE COAST AND
VALLEYS. NOT MUCH CHANGE TO ONLY SLIGHT COOLING FOR THE DESERTS ON
THURSDAY AND FRIDAY.
THE LOCAL NAM-BOUNDED WRF SHOWS A WEAK COASTAL EDDY FOR THE NEXT
FEW NIGHTS WITH PATCHY LOW CLOUDS AND FOG RETURNING FOR THE
COASTAL WATERS AND ADJACENT AREAS NEAR THE COAST FOR TONIGHT INTO
THURSDAY MORNING AND AGAIN FOR THURSDAY NIGHT INTO FRIDAY MORNING.
LONG TERM (SATURDAY THROUGH TUESDAY)
WEAK ONSHORE FLOW WILL CONTINUE TO SPREAD COOLING INLAND FOR THE
WEEKEND WITH SUNDAY HIGH TEMPERATURES NEAR AVERAGE AT THE COAST TO
8 TO 12 DEGREES ABOVE AVERAGE FOR THE MOUNTAINS, DESERTS, AND
INLAND VALLEYS, IN THE LOWER TO MID 70S FOR THE INLAND VALLEYS AND
AROUND 80 FOR THE LOWER DESERTS.
THE LOCAL NAM-BOUNDED WRF CONTINUES A COASTAL EDDY INTO THE
WEEKEND WITH MORE WIDESPREAD LOW CLOUDS AND FOG OVER THE COASTAL
WATERS AND ADJACENT COASTAL AREAS FOR FRIDAY NIGHT INTO SATURDAY
MORNING.
AROUND TUESDAY OF NEXT WEEK, A LOW PRESSURE SYSTEM MOVING QUICKLY
INLAND THROUGH CALIFORNIA COULD BRING STRONGER AND GUSTY WEST
WINDS FOR THE MOUNTAINS AND DESERTS AND A CHANCE OF SHOWERS. NBM
CHANCES FOR MEASURABLE PRECIPITATION FOR TUESDAY AND TUESDAY NIGHT
FROM THE COASTAL WATERS TO MOUNTAINS HAS INCREASED TO AROUND 35
PERCENT. ECMWF ENSEMBLE OUTPUT SHOWS GREATER SPREAD IN THE
INTENSITY OF THIS SYSTEM AND LESS WITH THE TIMING.
HIGH TEMPERATURES FOR CHRISTMAS COULD FALL TO NEAR TO A FEW
DEGREES BELOW AVERAGE FOR THE COAST AND VALLEYS, MOSTLY INTO THE
60S WITH THE LOWER DESERTS REMAINING AROUND 5 DEGREES ABOVE
AVERAGE, IN THE LOWER TO MID 70S.
AVIATION
181030Z....MOSTLY CLEAR SKIES TODAY AND TONIGHT. AREAS OF STRONG
NORTHEAST WINDS WILL CONTINUE, BUT GRADUALLY DECREASE DURING THE
DAY. GUSTS 20-35 KNOTS ARE EXPECTED IN FOOTHILLS AND PARTS OF INLAND
VALLEYS THROUGH 17Z, WITH A GRADUAL DECREASE THEREAFTER. AREAS OF
LLWS WILL OCCUR FROM SBD TO ONT, TO SNA, AS WELL AS MODERATE
UP/DOWNDRAFTS IN THE LEE (SOUTH AND WEST) OF MOUNTAINS THIS MORNING.
MARINE
NO HAZARDOUS MARINE WEATHER CONDITIONS ARE EXPECTED THROUGH SUNDAY.
BEACHES
A LARGE, LONG-PERIOD WESTERLY SWELL WILL ARRIVE THIS WEEKEND,
BRINGING LARGE SURF ON SUNDAY WITH SOME SETS EXCEEDING 10 FEET.
ADDITIONAL SWELLS NEXT WEEK COULD MAINTAIN HIGH SURF CONDITIONS FOR
SEVERAL DAYS. THIS LARGE SURF WILL MAKE SWIMMING CONDITIONS
HAZARDOUS AND COULD PRODUCE COASTAL IMPACTS. STAY TUNED FOR UPDATES.
FIRE WEATHER
SANTA ANA WINDS WILL CONTINUE INTO THIS MORNING WITH GUSTS TO 45
MPH ALONG AND BELOW THE COASTAL SLOPES OF THE MOUNAINS WITH ISOLATED
GUSTS TO 55 MPH. THE WINDS WILL DIMINISH DURING THE AFTERNOON AND
EVENING. LOWEST HUMIDITY FOR INLAND AREAS WILL FALL TO 10 TO 15
PERCENT TODAY. FOR THURSDAY THROUGH SUNDAY, WEAK ONSHORE FLOW
WILL RETURN SPREADING GRADUAL COOLING AND HIGHER COASTAL HUMIDITY
INLAND.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...WIND ADVISORY UNTIL NOON PST TODAY FOR ORANGE COUNTY INLAND
AREAS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY
MOUNTAINS-SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE
INLAND EMPIRE-SAN DIEGO COUNTY MOUNTAINS-SAN DIEGO COUNTY
VALLEYS-SAN GORGONIO PASS NEAR BANNING-SANTA ANA MOUNTAINS
AND FOOTHILLS.
PZ...NONE.
PUBLIC/FIRE WEATHER...17
AVIATION/MARINE/BEACHES...MM
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