738
FXUS66 KSGX 211611
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
911 AM PDT TUE OCT 21 2025
SYNOPSIS
COOLING WILL BEGIN TO SPREAD INLAND INTO COASTAL AREAS TODAY WITH
GREATER COOLING OF HIGH TEMPERATURES ON WEDNESDAY OF AS MUCH AS 12
TO 18 DEGREES FOR THE MOUNTAINS AND FAR INLAND VALLEYS. FOR
WEDNESDAY AND THURSDAY, THERE WILL BE PERIODS OF STRONGER
SOUTHWEST TO WEST WINDS ALONG AND BELOW THE EAST SLOPES OF THE
MOUNTAINS WITH GUSTS TO 35 TO 45 MPH. THERE IS A SLIGHT CHANCE OF
LIGHT SHOWERS FOR LATE WEDNESDAY NIGHT FOR THE SAN DIEGO COUNTY
COAST AND VALLEYS. THERE WILL BE SEVERAL DEGREES OF WARMING FOR
THURSDAY AND FRIDAY WITH HIGH TEMPERATURES ON FRIDAY FOR INLAND
AREAS AROUND 5 DEGREES ABOVE AVERAGE. A LOW PRESSURE SYSTEM MOVING
INLAND TO THE NORTH WILL BRING COOLER AND BREEZY CONDITIONS FOR
THE WEEKEND WITH A SLIGHT CHANCE OF LIGHT SHOWERS FOR LATE
SATURDAY NIGHT INTO SUNDAY FOR THE COAST TO THE MOUNTAINS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHORT TERM
PATCHY MARINE LAYER FOG THAT IMPACTED COASTAL AREAS UP TO ABOUT 5
MILES INLAND THIS MORNING IS GRADUALLY CLEARING. WE'RE GETTING
INTO DENSE FOG SEASON AS FALL PROGRESSES, AND THIS MORNING WAS AN
EXAMPLE WITH VISIBILITIES UNDER THE LOW CLOUDS AS LOW AS JUST
UNDER A QUARTER MILE. MEANWHILE, A BAND OF CLOUDS IS MOVING NORTH
OVER ALONG THE EASTERN EDGE OF A LARGE LOW OVER THE OCEAN TO THE
SOUTHWEST OF SAN DIEGO. THERE'S ACTUALLY A LITTLE BIT OF
PRECIPITATION IN THESE CLOUDS, BUT THEY'RE BASED AROUND
12,000-15,000 FEET AND RESULTING IN VIRGA (PRECIPITATION
EVAPORATING BEFORE IT HITS THE GROUND) RATHER THAN ANY RAIN.
THE MID-LEVEL LOW WILL START TO MOVE NORTHEAST TOWARDS THE COAST
TODAY, RESULTING IN COOLER TEMPERATURES THIS AFTERNOON FOR THE
COASTS AND VALLEYS, BUT SIMILAR HIGHS TO YESTERDAY FOR THE
MOUNTAINS, DESERTS, AND MOST OF THE IE. THE LOW WILL MOVE ONSHORE
SOUTH- CENTRAL CA NEAR PT. CONCEPTION WEDNESDAY MORNING INTO THE
AFTERNOON. THIS WILL HAVE A FEW EFFECTS ON THE LOCAL REGION, MOST
NOTICEABLY A DEEPER MARINE LAYER THAT WILL BRING CLOUDS MUCH
FURTHER INLAND THAN THIS MORNING, AND MUCH COOLER AFTERNOON
TEMPERATURES WEDNESDAY ANYWHERE FROM A FEW DEGREES COOLER THAN
TODAY (IMMEDIATE COAST) TO 12-18 DEGREES LOWER THAN TODAY
(MOUNTAINS AND WESTERN FOOTHILLS). THE DEEPENING MARINE LAYER WILL
LIKELY RESULT IN SOME SPOTS OF DRIZZLE OVER THE COASTS AND
VALLEYS WEDNESDAY MORNING.
THIS WILL ALSO LEAD TO STRONGER WINDS WEDNESDAY AFTERNOON AND
EVENING, NOTABLY FOR THE LEE-SIDE OF THE MOUNTAINS/DESERT
FOOTHILLS AND THE DESERTS, ESPECIALLY FOR THOSE TYPICALLY WINDY
GAPS LIKE THE BANNING PASS AND THE PASSES ALONG I-8 NEAR THE EAST
MOUNTAIN FOOTHILLS AS WELL AS ON THE IMPERIAL COUNTY LINE. WIND
GUSTS OF 25-40 MPH ARE LIKELY THROUGHOUT THESE AREAS, POSSIBLY UP
TO 50 MPH THROUGH THE AFOREMENTIONED PASSES. AS THE LOW CONTINUES
TO THE NORTH OF THE REGION, THERE COULD BE SOME SPOTTY LIGHT
SHOWERS LATE WEDNESDAY, MOST LIKELY (10-15%) FOR COASTAL SAN DIEGO
COUNTY. THE LOW CONTINUES INTO THE DESERT SOUTHWEST THURSDAY
MORNING, CUTTING OFF ANY SHOWER CHANCES AND LEADING TO THE
WEAKENING WEST WINDS IN THE DESERTS AND DESERT FOOTHILLS TURNING
WEAKLY OFFSHORE THURSDAY MORNING THROUGH THE EARLY AFTERNOON. HIGH
PRESSURE WILL START TO BUILD INTO THE REGION BEHIND THE LOW, AND
HIGH TEMPERATURES WILL START TO INCREASE AGAIN ALONG WITH A
SHALLOWER MARINE LAYER FOR THE END OF THE WEEK.
LONG TERM (FRIDAY THROUGH MONDAY)...ISSUED 351 AM PDT TUE OCT 21
THE WARMING WILL CONTINUE INTO FRIDAY WITH FRIDAY HIGH
TEMPERATURES FOR INLAND AREAS AROUND 5 DEGREES ABOVE AVERAGE. HIGH
TEMPERATURES ON FRIDAY WILL RANGE FROM THE LOWER 70S NEAR THE
COAST TO THE LOWER TO MID 80S FOR THE INLAND EMPIRE WITH THE LOWER
90S FOR THE LOWER DESERTS.
FOR THE WEEKEND, A LOW PRESSURE SYSTEM TO THE NORTH WILL
STRENGTHEN THE ONSHORE FLOW ACROSS SOUTHERN CALIFORNIA. THE MARINE
LAYER WILL DEEPEN AND THERE WILL BE PERIODS OF STRONGER AND GUSTY
WEST WINDS FOR THE MOUNTAINS AND DESERTS. THERE WILL BE COOLING OF
SEVERAL DEGREES DURING THE WEEKEND WITH SUNDAY HIGH TEMPERATURES
AS MUCH AS 4 TO 8 DEGREES BELOW AVERAGE FOR THE VALLEYS. SUNDAY
HIGH TEMPERATURES WILL RANGE FROM AROUND 70 NEAR THE COAST TO THE
70S FOR THE INLAND EMPIRE WITH THE MID TO UPPER 80S FOR THE LOWER
DESERTS. THERE IS A SLIGHT CHANCE OF LIGHT SHOWERS LATE SATURDAY
NIGHT INTO SUNDAY MORNING FROM THE COAST TO THE MOUNTAINS.
HIGH PRESSURE WILL BRING A WARMING TREND FOR MONDAY THROUGH
WEDNESDAY OF NEXT WEEK. THERE COULD BE WEAK OFFSHORE FLOW FOR
TUESDAY AND WEDNESDAY OF NEXT WEEK WITH THE GREATER WARMING FOR
THE COAST AND VALLEYS.
AVIATION
211530Z....COAST/VALLEYS...LOW CLOUDS AND FOG ARE BEGINNING TO
SCATTER OUT AND SHOULD CLEAR BY 17Z, BUT PATCHY LOW CLOUDS MAY
LINGER AT SOME BEACHES THROUGH THE AFTERNOON. LOW CLOUDS WILL PUSH
ASHORE AFTER 03Z THIS EVENING AND HEAD INLAND, FILLING THE COASTAL
BASIN OVERNIGHT INTO WEDNESDAY. INITIAL BASES WILL BE 600-1200 FEET
MSL, BUT RAPIDLY RISE ABOVE 2000 FEET MSL BY 16-17Z WEDNESDAY.
OTHERWISE...SCT-BKN CLOUDS 10000-15000 FEET MSL WITH VFR CONDITIONS
THROUGH THE TAF PERIOD.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH SATURDAY.
SGX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...CSP
AVIATION/MARINE...VILLAFANE
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