225
FXUS66 KSGX 062127
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
227 PM PDT MON OCT 6 2025
SYNOPSIS
HIGH PRESSURE TO THE SOUTHEAST WILL BRING GRADUALLY WARMER DAYS
INTO WEDNESDAY. THE MARINE LAYER WILL DECREASE IN DEPTH WITH NIGHT
AND MORNING LOW CLOUDS NOT SPREADING AS FAR INTO THE VALLEYS BY
WEDNESDAY. THURSDAY INTO SATURDAY, MOISTURE FROM THE REMNANTS OF
HURRICANE PRISCILLA IS EXPECTED TO SPREAD INTO THE SOUTHWESTERN
CALIFORNIA WITH CHANCES FOR SHOWERS PEAKING ON FRIDAY. LOW
PRESSURE FROM THE NORTHWEST WILL BRING COOLING FOR NEXT WEEKEND
WITH HIGH TEMPERATURES AS MUCH AS 5 TO 10 DEGREES BELOW AVERAGE
FOR INLAND AREAS NEXT SUNDAY.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHORT TERM
AFTERNOON HIGH TEMPERATURES ARE WARMER THAN YESTERDAY BY A DEGREE
OR FIVE AS HEIGHTS RISE SLIGHTLY LOCALLY WITH THE INTRUSION OF
WEAK RIDGING FROM THE EAST, WITH WEAK LOW PRESSURE OFF THE SOUTH-
CENTRAL CA COAST AT THE WEST END OF A BROAD, NEGATIVELY TITLED
TROUGH OVER THE NORTHWEST U.S. A GRADUAL WARMING TREND CONTINUES
THROUGH WEDNESDAY AS THE RIDGE CONTINUES TO NUDGE IN, BRINGING
HIGH TEMPERATURES TO JUST ABOUT AVERAGE BY MID-WEEK.
THE MARINE INVERSION WILL STRENGTHEN AND LOWER SLIGHTLY
IN THE NEXT FEW DAYS, WITH MORE COASTAL LOW CLOUDS IN THE LATE
EVENING THROUGH MID- TO LATE-MORNING EACH DAY THROUGH WEDNESDAY
NIGHT. LOW CLOUDS LOOK TO START OUT PATCHY AGAIN THIS EVENING,
BECOMING MORE CONSISTENT/WIDESPREAD TOWARDS 9-10 PM. NOT THE BEST
POSSIBLE VIEWING CONDITIONS FOR THE SUPERMOON AT THE IMMEDIATE
COAST, BUT IT WILL VERY LIKELY BE VISIBLE MOST COASTAL AREAS IN
THE EARLIER EVENING BEFORE THE CLOUDS BUILD IN, WITH GREAT
VISIBILITY FARTHER INLAND.
LONG TERM
REMNANT MOISTURE FROM NOW HURRICANE PRISCILLA WILL START TO MOVE
INTO THE AREA LATE WEDNESDAY INTO THURSDAY MORNING, DRAWN IN BY
SOUTHWEST FLOW FROM A LARGE LOW PRESSURE SYSTEM MOVING DOWN THE
OR/NORTHERN CA COAST. ENSEMBLE MODEL PWAT RISES TO JUST ABOVE AN
INCH BY THE END OF THE DAY THURSDAY, THEN PEAKS AROUND 1.5" BY
FRIDAY. THE AVERAGE PWAT FOR THIS TIME OF YEAR IS JUST UNDER
0.75", SO THIS IS WELL ABOVE AVERAGE. HOWEVER, REMAINING MODEL
SPREAD AND LIKELY A LACK OF STRONG FORCING MAKES FOR A LOW
CONFIDENCE FORECAST.
WHAT WE DO HAVE A WIDESPREAD 15-20% CHANCE FOR MEASURABLE (>=
0.01"), GENERALLY SHOWERY PRECIPITATION ACROSS THE REGION AS EARLY
AS THURSDAY MORNING, INCREASING TO 25-35% THURSDAY INTO FRIDAY.
RAINFALL TOTALS ARE STILL IN QUESTION WITH MODEL UNCERTAINTY
REMAINING (DESPITE BETTER AGREEMENT TODAY). 24 HOUR TOTAL
PROBABILITIES OF RAINFALL >= 0.25 ARE ABOUT 20% OVER SOUTHERN AND
EASTERN PORTIONS OF THE AREA AND 30% OVER THE MOUNTAINS AND PARTS
OF THE DESERTS BY LATE FRIDAY.
PROBABILITY FOR >=1.00" IS ABOUT 10%, LOCALLY 15%, OVER THE SD,
RIVERSIDE, AND EASTERN SBD MOUNTAINS AND PARTS OF THE DESERTS. THE
MAJORITY OF ENSEMBLE MEMBERS SHOW GENERALLY LIGHT PRECIPITATION
FOR WEST OF THE MOUNTAINS WITH A FEW STAND OUT MEMBERS, BUT THERE
IS THE POTENTIAL FOR FAIRLY GOOD UPSLOPE FLOW UNDER THE SOUTHWEST
WINDS ALOFT, ESPECIALLY FOR PARTS OF THE SBD MOUNTAINS. ANOTHER
POINT OF UNCERTAINTY IS THE THUNDERSTORM POTENTIAL. DYNAMICS
DON'T LOOK GREAT, WITH MINIMAL MUCAPE EVEN AT ITS PEAK ON
SATURDAY, BUT ENOUGH FOR A 10-15% CHANCE FOR THUNDERSTORMS MOST
OVER THE MOUNTAINS AND SD DESERT.
THE NORTHWEST TROUGH MOVES MORE FULLY INTO THE REGION LATE
SATURDAY/SUNDAY, EFFECTIVELY CUTTING OFF THE MOISTURE SOURCE AND
ALSO COOLING TEMPERATURES BACK TO 5-10 DEGREES BELOW AVERAGE OVER
THE WEEKEND INTO EARLY NEXT WEEK.
AVIATION
061930Z....COASTS/VALLEYS...INTERMITTENT PATCHY CIGS WILL CONTINUE
AT THE COAST THROUGH THE AFTERNOON WITH BASES MAINLY 1500-2000 FT
MSL. LOW CLOUDS WITH BASES 1200-1800 FT MSL WILL BECOME MORE
WIDESPREAD 03-06Z TUE. THERE IS A 40% CHANCE OF CIGS REACHING KONT
11-14Z TUE, WITH LESSER CHANCES FOR LOW CLOUDS TO REACH KSBD. AREAS
OF VIS 3-5SM HZ IN PORTIONS OF THE VALLEYS AND NEAR HIGHER COASTAL
TERRAIN. LOW CLOUDS WILL CLEAR 17-19Z TUE WITH THE POTENTIAL FOR LOW
CLOUDS TO AGAIN LINGER ALONG PORTIONS OF THE COAST INTO TUE
AFTERNOON.
MOUNTAINS/DESERTS...MOSTLY CLEAR AND VFR CONDITIONS INTO TUE.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH THURSDAY. FRIDAY
AFTERNOON, THERE IS A 5-10% CHANCE OF THUNDERSTORMS WITHIN 10
NAUTICAL MILES OF THE COAST.
SGX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...CSP
AVIATION/MARINE...CO
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