222
FXUS66 KSGX 180332
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
832 PM PDT TUE JUN 17 2025
SYNOPSIS
HIGH PRESSURE WILL DOMINATE THE REGION THROUGH WEDNESDAY LEADING
TO CONTINUED HOT WEATHER FOR INLAND AREAS. AN AREA OF LOW PRESSURE
WILL SPREADING COOLING ACROSS OUR AREA STARTING THURSDAY INTO THE
WEEKEND. BY THE WEEKEND, HIGH TEMPERATURES WILL BE NEAR 5 TO 10
DEGREES BELOW NORMAL WITH A DEEPER MARINE LAYER. THE COOLER
WEATHER PATTERN WILL CONTINUE INTO EARLY NEXT WEEK AS A TROUGH
LINGERS OVER OUR AREA.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
UPDATE: THE SUBTROPICAL HIGH PARKED OVER CENDROS ISLAND IN CENTRAL
BAJA CALIFORNIA WITH 500 MB HEIGHTS OF AROUND 595 DM HAS BEEN
INFLUENCING THE REGION WITH ABOVE AVERAGE TEMPERATURES. THE AXIS OF
THIS RIDGE WILL INITIALLY BEGIN TO SHIFT MORE WESTWARD AND ALLOW FOR
THERE TO BE SOME AMPLIFICATION GOING INTO TOMORROW WITH HOTTER
TEMPERATURES STILL IN PLACE AND VERY LITTLE CHANGE FROM WHERE THE
HIGHS WERE TODAY. THIS WILL BEGIN TO BREAK DOWN AND PROPAGATE MORE
TOWARDS THE EAST BEGINNING THURSDAY AS A LONGWAVE TROUGH UPSTREAM
OVER THE NORTHWESTERN CONUS BEGINS TO DEEPEN. WINDS WILL INCREASE
OUT OF THE WEST-SOUTHWEST ACROSS THE HIGH DESERTS AND BANNING/SAN
GORGONIO PASS, ALTHOUGH AT THIS TIME, THESE WINDS LOOK TO REMAIN
BELOW THE THRESHOLD. THIS WILL HELP TO BRING BACK MORE OF A
PERSISTENT ONSHORE FLOW, AND ALSO ALLOW FOR TEMPERATURES TO
GRADUALLY BEGIN TO COOL GOING INTO THE WEEKEND, WITH TEMPERATURES
EVEN DROPPING BELOW THE SEASONAL AVERAGE, ESPECIALLY FOR THE
INLAND AREAS. AS AN EXAMPLE, A HIGH OF 100F FOR RIVERSIDE TOMORROW
WILL BE REPLACED BY A MUCH MORE PLEASANT 82F FOR A HIGH ON
SATURDAY. ENSEMBLES HAVE BEEN CONSISTENTLY SHOWING AN OVERALL DEEP
TROUGH REMAINING OVER THE WESTERN STATES, WHICH SHOULD ALLOW FOR
TEMPERATURES TO REMAIN ON THE COOLER SIDE THROUGH THE END OF NEXT
WEEK.
(PREVIOUS DISCUSSION SUBMITTED AT 141 PM):
SHORT TERM (THROUGH FRIDAY)
CLEAR SKIES WERE SEEN ACROSS SOCAL EARLY THIS AFTERNOON AS HIGH
PRESSURE STRENGTHENS OVER THE SOUTHWESTERN U.S. ANOTHER DAY OF WARM
WEATHER IS OCCURRING AWAY FROM THE COAST WITH CURRENT TEMPERATURES
IN THE 80S AND 90S ACROSS MOST VALLEY LOCATIONS WITH HIGHS NEAR 110
DEGREES IN THE COACHELLA VALLEY. HIGH PRESSURE WILL PEAK IN
INTENSITY ON WEDNESDAY, WHERE 850 MB TEMPERATURES ARE EXPECTED TO
REACH NEAR 30C. THIS WILL LEAD TO CONTINUED HOT WEATHER FOR INLAND
AREAS. HIGH TEMPERATURES HAVE BEEN INCREASED BY A FEW DEGREES FOR
SOME WESTERN VALLEYS TO ACCOMMODATE FOR THIS WARMING TREND, WHERE
HIGHS ARE IN THE 90S FOR INLAND VALLEYS OF SAN DIEGO AND NEAR 100
DEGREES FOR THE INLAND EMPIRE. THE HIGH DESERT WILL ALSO SEE THE
HOTTEST TEMPERATURES OF THE WEEK ON WEDNESDAY AS WELL, WITH A
MODERATE TO HIGH CHANCE IN SEEING TEMPERATURES HIT 105 DEGREES OR
HIGHER. THE STRONG AREA OF HIGH PRESSURE WILL CONTINUE TO LEAD TO
A SUPPRESSED MARINE LAYER, WHERE ONLY PATCHY LOW CLOUDS ARE
EXPECTED ACROSS SAN DIEGO BY EARLY MORNING ON WEDNESDAY.
A TROUGH OF LOW PRESSURE WILL MOVE INTO THE PACIFIC NORTHWEST ON
THURSDAY, WHERE ITS INFLUENCE WILL BEGIN TO BE FELT BY THIS TIME.
THIS WILL BRING GREATER ONSHORE FLOW AND COOLING TO THE REGION, WITH
MOST INLAND AREAS LOWERING ANOTHER 5 DEGREES FROM WEDNESDAY. THE
AREA OF LOW PRESSURE IS EXPECTED TO PLUNGE SOUTHWARD BY FRIDAY INTO
THE WEEKEND, WITH HIGHS COOLING ANOTHER 3 TO 5 DEGREES.
LOWERING PRESSURE HEIGHTS WILL ALSO HELP BUILD THE MARINE LAYER WITH
LOW CLOUDS AND PATCHY FOG COMING BACK TO COASTAL AREAS AND WESTERN
VALLEYS BY THE END OF THE WORK WEEK.
LONG TERM (THIS WEEKEND AND BEYOND)
THE TROUGH AXIS OF THE AREA OF LOW PRESSURE WILL MOVE THROUGH SOCAL
OVER THE WEEKEND. THIS WILL BRING THE COOLEST WEATHER OF THE WEEK BY
SATURDAY, WHERE INLAND TEMPERATURES WILL BE ANOTHER 5 TO 10 DEGREES
COOLER FROM FRIDAY. ON SATURDAY, WE CAN EXPECT HIGHS IN THE 70S AND
80S FOR ALL AREAS EXPECT THE HIGH DESERTS WHICH WILL STAY NEAR 100
DEGREES AND THE BEACHES STICKING INTO THE UPPER 60S. A SERIES OF
WEAK WAVES ACROSS THE NORTHERN ROCKIES WILL KEEP THE TROUGHING
PATTERN IN PLACE, KEEPING THE BELOW AVERAGE TEMPERATURES AROUND INTO
EARLY NEXT WEEK. DRY CONDITIONS WILL CONTINUE ACROSS THE REGION FOR
THE LONG TERM PERIOD WITH MOSTLY CLEAR SKIES FOR THE MOUNTAINS AND
DESERTS AND MARINE LAYER CLOUDS EACH NIGHT AND MORNING WEST OF THE
MOUNTAINS.
AVIATION
180315Z....COAST/WESTERN VALLEYS...MOSTLY CLEAR SKIES THROUGH THE
EVENING. AREAS OF LOW CLOUDS WILL DEVELOP AFTER 06Z WITH BASES 500-
900 FEET MSL AND VIS 3-6 SM IN BR, BUT LOCALLY 0-2SM ON HIGHER
TERRAIN. SCATTER OUT WEDNESDAY 14-16Z. MORE UNIFORM LOW CLOUDS WILL
MOVE INLAND AGAIN AFTER 03Z THU, WITH SLIGHTLY HIGHER BASES 700-1000
FT MSL AND GREATER INLAND EXTENT TO 10-15 MILES FROM THE COAST.
INLAND VALLEYS/MOUNTAINS/DESERTS
CLEAR SKIES AND UNRESTRICTED VIS
THROUGH WEDNESDAY.
MARINE
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 WEDNESDAY 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.
UPDATE...STEWEY
PUBLIC...APR
AVIATION/MARINE...CSP
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