738
FXUS66 KSGX 200332
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
832 PM PDT THU JUN 19 2025
SYNOPSIS
LOW PRESSURE MOVING ASHORE ALONG THE WEST COAST WILL BRING A
COOLING TREND INTO THE WEEKEND. THIS WILL USHER IN ELEVATED WINDS
TO THE MOUNTAINS AND DESERTS, ALONG WITH A DEEP MARINE LAYER
ACCOMPANIED BY EXTENSIVE NIGHT AND MORNING LOW CLOUDS WEST OF THE
MOUNTAINS. THE LOW PRESSURE PATTERN WILL WEAKEN BY NEXT WEEK,
LEADING TO GRADUAL WARMING WITH LESS WIND INLAND.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
UPDATE: LATEST SATELLITE IMAGERY DISPLAYS A BROAD COLLECTION OF LOW
CLOUDS OVER THE INNER SOCAL BIGHT, WHICH WILL CONTINUE TO SURGE
INLAND THROUGHOUT THE EVENING. THERE WILL ALSO LIKELY BE SOME AREAS
OF PATCHY FOG DEVELOPING, BOTH OVER THE WATERS AND FOR HIGHER
ELEVATIONS ALONG THE COAST WHERE THE CLOUDS WILL INTERSECT, AND
PORTIONS OF THE INLAND VALLEYS AS WELL. OVER THE COURSE OF THE
NEXT COUPLE OF DAYS AS WE BEGIN TO BECOME MORE INFLUENCED BY THE
TROUGH WITH AN ASSOCIATED AREAS OF LOW PRESSURE UPSTREAM. WITH AN
ENHANCEMENT OF THE MARINE LAYER, THERE WILL LIKELY BE A MORE
PERSISTENT EXTENT OF CLOUDS INTO THE FURTHER INLAND AREAS (AS
BASES WILL RISE) AND SKIES WILL LIKELY REMAIN BROKEN TO OVERCAST
FOR THE COASTAL AREAS THIS WEEKEND, WITH ONLY PARTIAL CLEARING FOR
THE INLAND AREAS. THERE COULD ALSO BE SOME DRIZZLE POSSIBLE FOR
THE COASTAL AND INLAND AREAS FROM SATURDAY NIGHT INTO SUNDAY
MORNING.
WINDS WILL ALSO CONTINUE TO INCREASE OVER THE HIGH DESERTS, AND ALSO
WITHIN THE SAN GORGONIO PASS AND FOR WIND-PRONED AREAS OF THE LOWER
DESERTS. GUIDANCE STILL HAS ENOUGH COVERAGE OF WIND GUSTS BEING
RIGHT AROUND, OR EXCEEDING THE THRESHOLD, FOR THE SAN GORGONIO PASS
TO WARRANT THE NEED FOR A WIND ADVISORY. THERE COULD ALSO BE SOME
AREAS OF BLOWING DUST FOR THESE LOCATIONS DUE TO THE WINDS. OTHER
THAN THAT, MODELS ARE STILL ON TRACK SHOWING THE TROUGH DEEPENING
FOR 1000-500 MB THICKNESS VALUES TO DROP DOWN TO 577-583 DM OVER THE
CWA, GIVING WAY TO MUCH COOLER TEMPERATURES FOR THIS WEEKEND,
ESPECIALLY ON SATURDAY, WHERE THE IE WILL LIKELY SEE HIGHS ONLY
AROUND 75 TO 80F...COMPARED TO THE VALUES BEING CLOSER TO AROUND
100F IN RECENT DAYS. ENSEMBLE MEMBERS STILL INDICATE THAT THE
TROUGH WILL WEAKEN WITH SLIGHT RIDGING OCCURRING OVER THE REGION
BY LATER NEXT WEEK, WITH A GRADUAL INCREASE OF TEMPERATURES
THROUGH THEN.
(PREVIOUS DISCUSSION SUBMITTED AT 236 PM):
AN AREA OF LOW PRESSURE CURRENTLY OFF THE COAST OF BRITISH
COLUMBIA WILL PUSH SOUTHWARD INTO THE WESTERN U.S. THROUGH THE
WEEKEND. THE AREA OF HIGH PRESSURE THAT BROUGHT THE HOT WEATHER TO
OUR AREA THE PAST COUPLE DAYS CONTINUES TO PROGRESS INTO THE
SOUTHERN PLAINS. THIS LEAVES US IN A WEAK TROUGHING PATTERN AS
THE MARINE LAYER HAS SLIGHTLY DEEPENED SINCE YESTERDAY. LOW CLOUDS
ARE CONTINUE TO FADE ACROSS THE BEACHES THIS AFTERNOON, WITH
CLOUDS COMING BACK ASHORE EARLY THIS EVENING. THE AREA OF LOW
PRESSURE WILL MOVE INTO THE PACIFIC NORTHWEST ON FRIDAY, FURTHER
DEEPENING THE MARINE LAYER, WHICH WILL HELP TO SPREAD GREATER
COOLING TO INLAND AREAS. EXPECT TEMPERATURES TO LOWER ANOTHER 5
DEGREES OR SO INTO TOMORROW AS THIS SYSTEM COMES CLOSER. AS THIS
MARINE LAYER DEEPENS, EXPECT LOW CLOUDS TO FILL IN MUCH OF THE
COASTAL BASIN EACH NIGHT.
THE TIGHTENING PRESSURE GRADIENT WILL ALSO CONTRIBUTE TO
INCREASED WINDS ACROSS THE MOUNTAINS AND DESERTS EACH AFTERNOON
AND EVENING. AS THE TROUGH APPROACHES, WIND GUSTS CURRENTLY ACROSS
THE NORTHERN MOUNTAINS AND DESERTS ARE CLOSE TO 20-35 MPH. WINDS
WILL INCREASE BY FRIDAY AND SATURDAY AS THE AREA OF LOW PRESSURE
DEEPENS ACROSS CALIFORNIA AND THE GREAT BASIN. NBM 75TH PERCENTILE
WINDS SHOW WIDESPREAD GUSTS OF 30-40 MPH ACROSS DESERT REGIONS,
WITH GUSTS OVER 50 MPH IN SOME OF THE PASSES. WEST WINDS WILL
FUNNEL THROUGH THE SAN GORGONIO PASS THESE DAYS WITH WINDS NEAR
55 MPH AT TIMES ALONG INTERSTATE 10. THIS HAS PROMPTED A WIND
ADVISORY TO BE ISSUED FOR FRIDAY AND SATURDAY IN THE PASS, WHERE
PEOPLE SHOULD WATCH FOR DIFFICULT DRIVING CONDITIONS AT TIMES IN
THE AFTERNOONS AND EVENINGS. MUCH MORE NOTICEABLE COOLER WEATHER
WILL ALSO BE FELT BY THIS WEEKEND WITH THE COOLEST TEMPERATURES
OCCURRING ON SATURDAY. COASTAL AREAS WILL SEE HIGHS UP TO 5 TO
DEGREES BELOW NORMAL, WITH OTHER INLAND AREAS SEEING HIGHS 5 TO
LOCALLY 15 DEGREES BELOW AVERAGE. HIGHS WILL BE IN THE UPPER 60S
TO LOWER 80S FOR MOST AREAS, WITH MOST SPOTS ACROSS THE LOWER
DESERTS STAYING BELOW THE 100 DEGREE MARK.
BY SUNDAY, THE MAIN PORTION OF THE AREA OF LOW PRESSURE TO THE
NORTH WILL PUSH FURTHER INTO THE NORTHERN ROCKIES AS THE FLOW
SPLITS ALOFT, WHERE ANOTHER WEAKER TROUGH WILL HANG ACROSS THE
AREA INTO MONDAY AND TUESDAY. THIS PATTERN WILL MAINTAIN A DEEPER
MARINE LAYER AND BELOW AVERAGE TEMPERATURES ACROSS THE REGION,
THOUGH LESS WIND FOR THE MOUNTAINS AND DESERTS AS THE PRESSURE
GRADIENT WEAKENS. WEAK FLOW ALOFT IS EVIDENT IN ENSEMBLE MODELS BY
THE MIDDLE OF NEXT WEEK WITH A POSSIBLE RIDGE OF HIGH PRESSURE
BUILDING IN ACROSS THE DESERT SOUTHWEST, WHICH WOULD LEAD TO
GRADUAL WARMING BY THE END OF THE WEEK.
AVIATION
200300Z....COAST/VALLEYS...SATELLITE SHOWS LOW CLOUDS HAVE BEGUN TO
MOVE INLAND, WITH CIGS FOR SAN DIEGO COUNTY COASTAL SITES, LIKELY TO
REACH ORANGE COUNTY BY 04-06Z. BASES GENERALLY 1200-1600FT MSL.
FURTHER INLAND SPREAD EXPECTED 9-11Z, WITH CIGS FOR THE INLAND
EMPIRE LIKELY 11Z-16Z. VIS WILL BE SLIGHTLY IMPROVED EVERYWHERE
OUTSIDE OF WHERE CLOUDS INTERSECT TERRAIN, GENERALLY ABOVE 4SM.
RETREAT OF CLOUDS TO THE COAST BY 16-18Z, ALTHOUGH CLOUDS MAY LINGER
AT THE BEACHES BEYOND THIS POINT. LOW CLOUDS PUSH INLAND AGAIN
FRIDAY EVENING, POSSIBLY A BIT EARLIER, AROUND 01Z SATURDAY, WITH
SLIGHTLY HIGHER BASES.
MOUNTAINS/DESERTS
CLEAR SKIES AND UNRESTRICTED VIS THROUGH
FRIDAY. WESTERLY WINDS WITH GUSTS 25-40 KNOTS THROUGH MOUNTAIN
PASSES LOCALLY INTO DESERTS, PRODUCING POCKETS OF UP/DOWNDRAFTS IN
LEE OF RIDGES THROUGH 11Z FRIDAY. SIMILAR BUT SLIGHTLY STRONGER
WINDS PICK UP AGAIN AFTER 21Z WITH MOD TO STRONG UP/DOWNDRAFTS NEAR
MOUNTAIN PEAKS. BLDU WITH VIS BELOW 3SM POSSIBLE AT TIMES THROUGH
FRIDAY EVENING.
MARINE
NORTHWEST WIND GUSTS AROUND 20 KNOTS NEAR SAN CLEMENTE ISLAND FRIDAY
AFTERNOON AND EVENING. OTHERWISE, 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...WIND ADVISORY FROM 11 AM FRIDAY TO 11 PM PDT SATURDAY FOR SAN
GORGONIO PASS NEAR BANNING.
PZ...NONE.
PUBLIC...APR
AVIATION/MARINE...ZUBER
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