458
FXUS66 KSGX 182117
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
217 PM PDT WED JUN 18 2025
SYNOPSIS
HIGH PRESSURE OVER THE REGION THAT HAS AIDED IN HOT INLAND WEATHER
WILL MOVE OFF TO THE EAST BY THURSDAY AND FRIDAY. IN ITS WAKE, AN
AREA OF LOW PRESSURE WILL MOVE SOUTHWARD INTO THE REGION. THIS
WILL BRING MORE NOTICEABLE COOLER WEATHER WITH BREEZIER CONDITIONS
ACROSS THE MOUNTAINS AND DESERTS INTO THE WEEKEND AND EARLY NEXT
WEEK. SUBTLE WARMING IS EXPECTED BY THE MIDDLE OF NEXT WEEK AS
HIGH PRESSURE OFF THE COAST MOVES CLOSER TO OUR AREA.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
A 592DM AREA OF HIGH PRESSURE IS CURRENTLY OVER ARIZONA IS
PROVIDING ANOTHER HOT AFTERNOON FOR INLAND AREAS. CURRENT
TEMPERATURES ACROSS THE MOUNTAINS AND INLAND EMPIRE ARE WELL INTO
THE 80S AND 90S WITH TRIPLE DIGIT HEAT ACROSS THE LOWER DESERTS.
THE MARINE LAYER IS EXPECTED TO DEEPEN SLIGHTLY OVERNIGHT,
PROVIDING A GREATER CHANCE OF CLOUD COVER BY MORNING ACROSS THE
COASTAL AREAS AND ADJACENT VALLEYS OF ORANGE AND SAN DIEGO
COUNTIES. THIS MAY ALSO LEAD TO FOGGY CONDITIONS OVER ELEVATED
TERRAIN AS WELL.
A LARGE AREA OF LOW PRESSURE OFF THE COAST OF BRITISH COLUMBIA
WILL PUSH SOUTHWARD INTO THE WEEKEND. HEIGHTS ARE EXPECTED TO
LOWER ON THURSDAY, WHERE TEMPERATURES WILL BE KNOCKED DOWN A FEW
DEGREES FROM TODAY. THE LOW WILL PUSH FURTHER SOUTH INTO THE GREAT
BASIN BY FRIDAY AND SATURDAY, FURTHER COOLING US OFF. HIGHS 5 TO
10 DEGREES ABOVE NORMAL TODAY WILL GO TO 5 TO 10 DEGREES BELOW
NORMAL BY SATURDAY. CONFIDENCE IS HIGH THAT AREAS WEST OF THE
MOUNTAINS WILL MAINLY BE IN THE 60S NEAR THE COAST, 70S IN MUCH OF
THE VALLEYS, WITH SOME LOWER 80S IN THE INLAND EMPIRE. THE SYSTEM
WILL BRING ELEVATED WIND GUSTS TO THE MOUNTAINS AND DESERTS EACH
DAY, MAINLY NEAR 25-40 MPH, LOCALLY HIGHER IN THE SAN GORGONIO
PASS. THE MARINE LAYER WILL SIGNIFICANTLY DEEPEN BY THE WEEKEND AS
WELL, WHERE CLOUDS AND FOG WILL PUSH INTO MUCH OF THE COASTAL
BASIN EACH NIGHT AND MORNING.
THE TROUGHING PATTERN STICKS AROUND INTO EARLY NEXT WEEK, THOUGH
NOT AS POTENT, WHICH WILL HELP TO WEAKEN WINDS SLIGHTLY. THE
MIDDLE OF THE WEEK STAYS DRY AS WEAK HIGH PRESSURE OFF THE COAST
BEGINS TO HAVE GREATER INFLUENCE OVER THE AREA. THIS WILL BRING
SOME WARMING TO THE AREA, THOUGH HIGHS DO NOT LOOK TOO FAR FROM
AVERAGE.
AVIATION
182030Z....COAST/WESTERN VALLEYS...MOSTLY CLEAR THROUGH 01Z. LOW
CLOUDS TO REDEVELOP AT THE COAST AFTER 01Z, AND EXTEND FARTHER
INLAND OVERNIGHT INTO THURSDAY. BASES SHOULD BE 700-1000 FEET MSL
AND VIS 1-5SM OVER HIGHER COASTAL TERRAIN AND WESTERN VALLEYS.
SCATTER OUT THURSDAY 16-18Z.
INLAND VALLEYS/MOUNTAINS/DESERTS
CLEAR SKIES AND UNRESTRICTED VIS
THROUGH THURSDAY.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH SUNDAY.
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH SUNDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR ORANGE COUNTY
INLAND AREAS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO AND
RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO COUNTY
MOUNTAINS-SAN DIEGO COUNTY VALLEYS-SANTA ANA MOUNTAINS AND
FOOTHILLS.
PZ...NONE.
PUBLIC...APR
AVIATION/MARINE...MM
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