155
FXUS66 KSGX 140954
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
254 AM PDT SUN SEP 14 2025
SYNOPSIS
SLIGHTLY BELOW NORMAL TEMPERATURES TODAY. A SLOW WARMING TREND
WILL BRING NEAR NORMAL TO ABOVE NORMAL TEMPERATURES FOR MONDAY
THROUGH WEDNESDAY. THE MARINE LAYER WILL ALSO BECOME SHALLOWER
THROUGH WEDNESDAY, WITH NIGHT AND MORNING CLOUDS RESTRICTED TO THE
COASTAL AREAS AND WESTERN PORTIONS OF THE INLAND VALLEYS. ELEVATED
MOISTURE FROM THE TROPICS COULD RETURN AS EARLY AS TUESDAY BUT THE
CHANCES FOR ANY CONVECTION WILL REMAIN VERY LOW UNTIL WEDNESDAY.
INCREASING MOISTURE FROM THE TROPICS WILL BRING CHANCES OF SHOWERS
AND THUNDERSTORMS MAINLY IN THE MOUNTAINS AND DESERTS EACH
AFTERNOON AND EVENING FOR WEDNESDAY INTO NEXT WEEKEND.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
THIS MORNING...THE MARINE LAYER IS ABOUT 2500 FT DEEP BUT THERE
ARE ONLY A FEW PATCHES OF LOW CLOUDS IN THE COASTAL AREAS. CLOUD
COVERAGE WILL INCREASE BUT WILL LIKELY BE LESS THAN SATURDAY
MORNING AND MOSTLY RESTRICTED TO THE COASTAL AREAS AND WESTERN
PORTIONS OF THE INLAND VALLEYS AS HEIGHTS RISE ALOFT WITH A
TRANSIENT RIDGE OVER SOCAL.
THE RIDGE WILL REMAIN IN PLACE THROUGH WED, SANDWICHED BETWEEN A
LOW PRESSURE SYSTEM MOVING INLAND OVER THE PAC NORTHWEST AND A
CLOSED UPPER LOW CURRENTLY ABOUT 620 MILES SOUTHWEST OF SAN DIEGO.
THE LOW TO THE SOUTHWEST WILL DRIFT CLOSER TO THE COAST AND COULD
ENTRAIN MID AND HIGH-LEVEL MOISTURE FROM THE TROPICS AS EARLY AS
TUESDAY, BUT THIS MOISTURE WILL BE LIMITED AND A LACK OF A STRONG
FORCING MECHANISM WILL ALL BUT PREVENT ANY CHANCES OF DEEP
CONVECTION...AT LEAST UNTIL WEDNESDAY. FOR WEDNESDAY INTO NEXT
WEEKEND, INCREASING MOISTURE AND INSTABILITY WILL BRING CHANCES
FOR SHOWERS/TSTMS EACH AFTERNOON/EVENING MAINLY IN THE MTNS AND
DESERTS BUT DEEP CONVECTION COULD ALSO DEVELOP WEST OF THE MTNS.
MEDIUM-RANGE MODELS ARE IN GOOD AGREEMENT THROUGH WEDNESDAY WITH
RESPECT TO THE PLACEMENT AND TIMING OF SYNOPTIC-SCALE FEATURES.
AFTER WEDNESDAY, SOLUTIONS BEGIN TO DIVERGE INTRODUCING MORE
UNCERTAINTY INTO THE FORECAST BUT MOST ENSEMBLE MEMBERS SHOW A LOW
PRESSURE SYSTEM INTENSIFYING OFF THE CA COAST AND DISPLACING THE
HIGH PRESSURE RIDGE TO THE EAST. A MAJORITY OF ENSEMBLE MEMBERS
ACROSS MODEL PLATFORMS FAVOR A DRY SOLUTION FOR SOCAL THROUGH
TUESDAY THEN A MAJORITY FAVOR A WET SOLUTION FOR WED THROUGH
SATURDAY. CONDITIONS COULD BEGIN TO DRY OUT NEXT SUNDAY AS WE LOSE
ACCESS TO THE MOISTURE FROM THE SOUTH.
THE UPPER RIDGE WILL BRING A GENERAL WARMING TREND THROUGH
WEDNESDAY WHICH WILL LIKELY BE THE WARMEST DAY, WITH DAYTIME HIGH
TEMPERATURES SEVERAL DEGREES ABOVE SEASONAL AVERAGES IN MOST
AREAS. THE INCREASING MOISTURE, CLOUD COVER AND PRECIP WILL COOL
THINGS OFF FOR THU INTO NEXT WEEKEND. BY NEXT SUNDAY, TEMPERATURES
COULD BE AS MUCH A 10 DEGREES BELOW SEASONAL AVERAGES FOR A FEW
INLAND AREAS.
THE MARINE LAYER WILL BECOME SHALLOWER FOR MONDAY INTO WED
MORNING, WITH LOW CLOUDS RESTRICTED TO THE COASTAL AREAS AND
WESTERN PORTIONS OF THE INLAND VALLEYS. FOR THE LATTER HALF OF THE
WEEK, THE MARINE LAYER COULD BECOME TOO WELL MIXED WITH THE AIR
ABOVE IT AND LOW CLOUDS WILL HAVE A DIFFICULT TIME FORMING.
AVIATION
140930Z...COAST/VALLEYS...PATCHY LOW CLOUDS BASED 1500-2000 FT MSL
ALONG THE SOUTH SAN DIEGO AND ORANGE COUNTY COASTS WILL BECOME MORE
WIDESPREAD ALONG THE COAST 10-12Z, SPREADING INTO PARTS OF THE
INLAND EMPIRE 12-14Z. 60% CHANCE FOR CIGS AT KONT AND 40% CHANCE FOR
KSBD BY 13Z THIS MORNING. CLOUDS CLEAR INLAND 16-17Z AND FOR COASTAL
AREAS 17-18Z, WITH MOSTLY CLEAR SKIES FOLLOWING THROUGH THIS EVENING
EXCEPT FOR A 30% CHANCE FOR LOW CLOUDS TO LINGER IN SOUTHERN SAN
DIEGO CO (LA JOLLA SOUTHWARDS) THROUGH JUST AFTER 19Z. LOW CLOUDS
1000-1500 FT MSL REDEVELOP AND MOVE INLAND UP TO ABOUT 15 MILES
AFTER 15/02Z. LIKE THIS MORNING, COVERAGE WILL LIKELY BE PATCHY AT
FIRST BUT GROW MORE UNIFORM TOWARDS 05Z.
MOUNTAINS/DESERTS...MOSTLY CLEAR AND VFR CONDITIONS THROUGH
TONIGHT.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH THURSDAY.
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...PG
AVIATION/MARINE...CSP
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