175
FXUS66 KSGX 130323
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
823 PM PDT FRI SEP 12 2025
SYNOPSIS
BELOW NORMAL TEMPERATURES INTO THE WEEKEND BEFORE A SLOW WARMING
INTO MIDDLE OF NEXT WEEK. A DEEPER MARINE LAYER PERSISTS INTO
SUNDAY MORNING BEFORE BECOMING MORE SHALLOW INTO WEDNESDAY.
THUNDERSTORM CHANCES RETURN FOR THE MOUNTAINS AS MONSOONAL
MOISTURE MOVES IN FOR THE LATTER HALF OF THE WEEK, WITH LOWER
CHANCES FOR THE VALLEYS AND DESERTS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
EVENING UPDATE...
MARINE LAYER LOW CLOUDS ARE FORMING ALONG THE COAST AGAIN THIS
EVENING, AS WILL AS ALONG SOME OF THE COASTAL MOUNTAIN SLOPES, AND
SHOULD FILL IN ACROSS THE COASTAL BASIN LATE TONIGHT. ELSEWHERE
SKIES ARE CLEAR. THE 00Z KNKX SOUNDING SHOWS THE MARINE INVERSION
BASED NEAR 2800 FT MSL, DEEPENING FROM THIS MORNING AS THE UPPER
LEVEL TROUGH MOVES INLAND ACROSS CA THIS EVENING. THIS LOW WILL
PROGRESS INLAND THIS WEEKEND, WITH WEAK TRANSITORY RIDGING
FOLLOWING IT OVER SO CAL LATE SATURDAY, THEN FLATTENING SUNDAY AS
AN UPPER TROUGH MOVES INLAND ACROSS THE PAC NW. THIS WILL ALLOW
FOR MINOR WARMING EACH DAY AND LESS EXTENSIVE NIGHT AND MORNING
LOW CLOUDS, THOUGH HIGHS WILL REMAIN SEVERAL DEGREES BELOW NORMAL
ACROSS THE REGION.
PREVIOUS DISCUSSION...
EARLY TO MID WEEK, THE RIDGE SHIFTS INTO THE COLORADO RIVER VALLEY
AND A SHORTWAVE BECOMES A CLOSED LOW AND SITS OFF THE COAST OF
CENTRAL CALIFORNIA. THIS PATTERN WILL ALLOW FOR SOME MONSOONAL
MOISTURE TO START PUSHING UP INTO THE DESERT SOUTHWEST FOR THE
LATTER HALF OF THE WEEK WHILE TEMPERATURES CONTINUE TO WARM WITH
THE RIDGE DISPLACED TO THE EAST. INCREASING HEIGHTS WILL LEAD TO A
SHALLOWER MARINE LAYER, WITH LIMITED INLAND EXTENT AFTER MONDAY.
TEMPERATURES WILL BE ABLE TO SUFFICIENTLY WARM FOR INLAND AND
MOUNTAIN AREAS NO LONGER BENEFITING FROM A MORNING MARINE LAYER,
WHILE THE DESERTS LOOK TO WARM A LITTLE SLOWER GIVEN THE UPTICK IN
MOISTURE FROM THE SOUTH. BY TUESDAY, HIGHS WILL RETURN TO AROUND
5 DEGREES ABOVE-NORMAL FOR INLAND REGIONS, REMAINING NEAR NORMAL
FOR THE DESERTS. TEMPERATURES PEAK ON WEDNESDAY IN THE UPPER 70S
TO UPPER 90S FOR THE COASTS AND INLAND AREAS, 70S AND 80S FOR THE
MOUNTAINS, AND 102-105F FOR THE DESERTS.
FOR THE LATTER HALF OF THE WEEK, MODELS CONTINUE TO DIFFER ON THE
UPPER LEVEL PATTERN. MOST AGREE WITH THE INFLUX OF MONSOONAL
MOISTURE WITH THE RIDGE AXIS OVER THE FOUR CORNERS AND LOW OFF
THE COAST, BUT NEWER RUNS SHOW A DEEPENING LOW OVER THE PACNW
TRAVERSING SOUTHWARD AND HELPING TO FLATTEN THE RIDGE ON THURSDAY.
IF THIS OCCURS, MORE ZONAL FLOW WILL ENSUE WITH COOLER WEATHER
INTO THE END OF THE WEEK. THIS COULD LIMIT THUNDERSTORM CHANCES
FOR THE MOUNTAINS AND DESERTS THURSDAY AND FRIDAY, CURRENTLY
HOVERING AROUND 20-40% CHANCE EACH AFTERNOON. THIS WILL BE
SOMETHING TO KEEP AN EYE ON IN THE COMING DAYS, WITH BOTH
TEMPERATURES AND MOISTURE KEY PLAYERS INTO WHETHER STORMS DEVELOP
ON THE BACK END OF NEXT WEEK.
AVIATION
130300Z...COAST/VALLEYS...PATCHY LOW CLOUDS BASED 1800-2200 FT MSL
HAVE DEVELOPED ALONG THE SD COUNTY COAST. THESE CLOUDS ARE
STRUGGLING TO FILL IN AND WILL LIKELY REMAIN SCATTERED UNTIL 06-07Z
WHEN CLOUDS WILL PUSH INLAND TO OC/SD VALLEYS AND COVERAGE WILL
INCREASE TO BKN-OVC, WHILE BASES LOWER TO AROUND 1500-2000FT MSL.
AROUND 11-13Z SAT MORNING, BASES WILL LIFT ABOVE 2000 FT MSL WHILE
SIMULTANEOUSLY DEVELOPING INTO THE INLAND EMPIRE WITH KONT AND KSBD
POTENTIALLY SEEING BRIEF CIGS AROUND 13Z. CLOUDS BEGIN TO SCATTER
OUT 15-17Z SATURDAY MORNING FOR THE INLAND VALLEYS, CLOSER TO 17-19Z
FOR THE IMMEDIATE COASTS, REDEVELOPING AROUND 00-02Z SUNDAY.
MOUNTAINS/DESERTS...MOSTLY CLEAR AND VFR CONDITIONS THROUGH SATURDAY.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH WEDNESDAY.
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...SS/ZUBER
AVIATION/MARINE...WESTERINK
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page