207
FXUS66 KSGX 192136
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
236 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...
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
192030Z....COAST/VALLEYS...LOW CLOUDS ALONG THE IMMEDIATE COAST
BASED AT 1000-1400 FEET MSL WITH TOPS TO 2200 FEET WILL BEGIN TO
MARCH INLAND AFTER 01Z, COVERING MOST OF THE COASTAL BASIN BY 13Z
FRIDAY. BASES SHOULD AROUND 1200-1500 FEET MSL WITH TOPS TO 2400
FEET, WITH VIS 3-5SM WHERE CLOUDS REACH FARTHEST INLAND.
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. SIMILAR BUT SLIGHTLY STRONGER WINDS
PICK UP AGAIN FRIDAY AFTER 21Z.
MARINE
NORTHWEST WIND GUSTS AROUND 20 KNOTS NEAR SAN CLEMENTE ISLAND FRIDAY
AFTERNOON AND EVENING. OTHERWISE, NO HAZARDOUS MARINE CONDITIONS ARE
EXPECTED THROUGH TUESDAY.
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...MM
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