202
FXUS66 KSGX 190932
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
232 AM PDT SUN OCT 19 2025
SYNOPSIS
WEAK OFFSHORE FLOW WILL CONTINUE TODAY. NEAR TO SLIGHTLY ABOVE
AVERAGE TEMPERATURES EXPECTED THROUGH MONDAY, BEFORE BELOW AVERAGE
CONDITIONS RETURN FOR THE MIDDLE OF THE WEEK. GRADUAL WARMING FOR
THE END OF THE WEEK, WITH COOLER CONDITIONS NEXT WEEKEND. PATCHES OF
MARINE LAYER LOW CLOUDS AND FOG WILL RETURN TO PARTS OF THE COASTAL
WATERS TODAY, WITH THE POTENTIAL FOR AREAS OF DENSE FOG. LOW CLOUD
COVERAGE WILL BECOME MORE WIDESPREAD INTO THE MIDDLE OF THE WEEK.
AREAS OF DRIZZLE POSSIBLE WEDNESDAY FOR AREAS WEST OF THE MOUNTAINS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
WEAK HIGH PRESSURE ALOFT WILL CONTINUE TO PREVAIL OVER THE AREA
EARLY THIS WEEK, KEEPING TEMPERATURES NEAR TO SLIGHTLY ABOVE
AVERAGE. PERIODS OF WEAK OFFSHORE WINDS FROM THE NORTHEAST TO EAST
WILL BE PRESENT ON THE COASTAL SLOPES OF THE MOUNTAINS, LOCALLY INTO
THE FOOTHILLS, THROUGH TUESDAY. THE PREVAILING OFFSHORE FLOW WILL
LIMIT MARINE LAYER LOW CLOUD AND FOG COVERAGE EARLY THIS WEEK. ANY
LOW CLOUDS AND FOG THAT DO DEVELOP WILL MOST LIKELY OCCUR OVER THE
COASTAL WATERS AND NEAR THE COAST WITH AREAS OF DENSE FOG POSSIBLE.
A CLOSED LOW THAT IS CURRENTLY WEST OF SOUTHERN CALIFORNIA WILL
BEGIN TO SLOWLY MOVE EAST MONDAY AND TUESDAY. BY WEDNESDAY, THE LOW
IS EXPECTED TO QUICKLY MOVE EAST ACROSS SOUTHERN CALIFORNIA. THIS
WILL BRING AN INCREASE IN CLOUD COVERAGE AND COOLER CONDITIONS.
WESTERLY WINDS MAY BECOME ELEVATED OVER THE MOUNTAINS, LOCALLY INTO
THE DESERTS. BY WEDNESDAY, HIGHS FOR INLAND LOCATIONS ARE EXPECTED
TO BE 7 TO 12 DEGREES BELOW AVERAGE, WITH SOME MOUNTAIN LOCATIONS
SEEING HIGHS 15 TO 20 DEGREES BELOW AVERAGE. RAIN CHANCES ASSOCIATED
WITH THIS SYSTEM CONTINUE TO LOOK MARGINAL. CHANCES OF MEASURABLE
RAINFALL OCCURRING REMAIN LESS THAN 10 PERCENT, WITH THE BEST
CHANCES FOR ANY ACCUMULATING RAIN ON THE COASTAL MOUNTAIN SLOPES.
AREAS OF PATCHY DRIZZLE ARE POSSIBLE WEST OF THE MOUNTAINS ON
WEDNESDAY, ESPECIALLY WITH THE INCREASE IN ONSHORE FLOW AND RAPID
DEEPENING OF THE MARINE LAYER.
AS THE LOW CONTINUES TO MOVE EAST WEAK RIDGING WILL SET UP AGAIN
OVER SOUTHERN CALIFORNIA FOR THURSDAY AND FRIDAY. THIS WILL BRING A
FEW DEGREES OF WARMING, WEAK OFFSHORE FLOW, AND A SHALLOWER MARINE
LAYER. FOR NEXT WEEKEND, WE'RE MONITORING THE POTENTIAL FOR A DEEP
TROUGH OF LOW PRESSURE FROM THE GULF OF ALASKA TO DIG SOUTH INTO THE
US WEST COAST. CURRENTLY, MOST OF THE ENSEMBLE GUIDANCE KEEPS THE
LOW OFF THE COAST OF THE PACIFIC NORTHWEST THROUGH NEXT SATURDAY,
WHICH WOULD KEEP US DRY THROUGH THEN. BY NEXT SUNDAY, MOST ENSEMBLE
GUIDANCE HAS THE TROUGH MOVING INLAND ALTHOUGH THERE REMAIN SOME
DIFFERENCES IN TIMING AND AMPLITUDE OF THE TROUGH. THERE IS FAIRLY
GOOD CONSENSUS THAT THE TRACK OF THE LOW WILL BE MORE INLAND, MAKING
IT LESS FAVORABLE FOR SIGNIFICANT PRECIPITATION TO OCCUR. THERE ARE
STILL SOME ENSEMBLE MEMBERS SHOWING LIGHT RAIN IS POSSIBLE, BUT MORE
THAN LIKELY THE MAIN IMPACT FROM THIS SYSTEM FOR OUR AREA OF
RESPONSIBILITY WILL BE AN UPTICK IN WINDS OVER THE MOUNTAINS AND
INTO THE DESERTS.
AVIATION
190900Z....COASTS...A FEW STRAY PATCHES OF VERY LOW MARINE CLOUDS
(BASED 100-400 FT MSL) ARE OFF SHORE THIS MORNING. THERE IS A SLIGHT
CHANCE (10%) FOR PATCHY FG FROM THESE CLOUDS AT THE COAST UNTIL 15Z
THIS MORNING. BETTER CHANCE (35-45%) FOR LOW CLOUDS AND FOG TO
DEVELOP ALONG THE COAST AFTER 09Z MONDAY.
VALLEYS/MOUNTAINS/DESERTS...VFR CONDITIONS CONTINUE THROUGH EARLY
MONDAY.
MARINE
PATCHY FOG WITH VISIBILITIES LIKELY UNDER 1 SM POSSIBLE OVER THE
WATERS THIS MORNING AND COULD BE MORE WIDESPREAD MONDAY AND TUESDAY
MORNINGS. OTHERWISE, NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED
THROUGH THURSDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...CO
AVIATION/MARINE...MUNYAN
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