873
FXUS66 KSGX 200407
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
907 PM PDT MON MAY 19 2025
SYNOPSIS
DRY WEATHER WILL CONTINUE INTO EARLY NEXT WEEK. HIGH TEMPERATURES
FOR THE COAST AND VALLEYS WILL WARM THROUGH WEDNESDAY AND FOR THE
DESERTS THROUGH THURSDAY WITH HIGH TEMPERATURES AROUND 10 DEGREES
ABOVE SEASONAL AVERAGES. THE MARINE LAYER WILL BECOME SHALLOWER
THROUGH THE MIDDLE OF THE WEEK WITH NIGHT AND MORNING COASTAL LOW
CLOUDS SPREADING LOCALLY INTO PORTIONS OF THE WESTERN VALLEYS AT
TIMES. THIS WILL BE FOLLOWED BY A COOLING TREND, WITH HIGH
TEMPERATURES AROUND AVERAGE FOR NEXT WEEKEND.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SKIES ARE CLEAR THIS EVENING UNDER WEAK HIGH PRESSURE WITH
NORTHWEST FLOW ALOFT. SFC PRESSURE GRADIENTS REMAIN ONSHORE BUT
ARE TRENDING WEAKER SO WINDS REMAIN WEAK. THE MARINE LAYER IS MUCH
SHALLOWER THAN YESTERDAY AND HIGH-RESOLUTION MODELS ARE SHOWING A
RETURN OF LOW CLOUDS AND PATCHY FOG TO THE COASTAL AREAS BETWEEN
ABOUT 2 AM AND 10 AM.
FROM PREVIOUS DISCUSSION...
AS THE HIGH PRESSURE RIDGE CONTINUES TO BUILD IN AND STRENGTHEN
OVER THE REGION, TEMPERATURES WILL ALSO CONTINUE ON AN UPWARD
TREND, AND HIGH TEMPERATURES TOMORROW WILL BE NOTICEABLY WARMER
THAN TODAY.
WEDNESDAY THROUGH THURSDAY...
LATEST MODEL GUIDANCE HAVE BROUGHT DOWN THE STRENGTH OF THE RIDGE
WITH HEIGHTS NOT QUITE AS HIGH AS THEY WERE IN PREVIOUS RUNS.
THIS WILL TRANSLATE TO TEMPERATURES BEING SLIGHTLY COOLER FROM
WHAT WAS INDICATED. A CONSENSUS OF THE DETERMINISTIC MODELS PUTS
THE AVERAGE 1000-500MB THICKNESS AT ROUGHLY 585 DM, WHICH IS LESS
THAN THE NEAR 590 DM THAT MODELS SHOWED EARLIER. DUE TO THIS,
HIGHS FOR BOTH WEDNESDAY AND THURSDAY WILL NOT BE QUITE AS HOT,
ALTHOUGH STILL ANYWHERE FROM 5 TO 10 DEGREES ABOVE THE SEASONAL
AVERAGE FOR THIS TIME OF YEAR FOR MOST AREAS. BECAUSE IT IS
GENERALLY A MODERATE RISK FOR MOST OF THE INLAND AREAS AND
DESERTS, WITH VERY IN THE WAY OF ANY AREAS WITH A HIGH RISK, A
HEAT ADVISORY HAS BEEN HELD OFF AT THIS TIME ALTHOUGH THIS WILL
CONTINUE TO BE ASSESSED IN THE UPCOMING DAYS. MORNING LOW CLOUDS
AND PATCHY FOG WILL LIKELY REMAIN LIMITED UNDER SUBSIDENCE, UNLESS
THERE BECOMES THE PRESENCE OF A WEAK COASTAL EDDY, WHICH IS
POSSIBLE.
FRIDAY THROUGH THE WEEKEND...
THE RIDGE IS GOING TO BEGIN TO BREAK DOWN AND TROUGHING UPSTREAM
OVER THE NORTHWEST REGION WILL CONTINUE TO ADVANCE TOWARDS THE
REGION AND ALLOW FOR THE INCREASE OF THE MARINE LAYER AND SLIGHTLY
COOLER TEMPERATURES AS A RESULT, CLOSER TO THE AVERAGE, AND THIS
COOLING TREND WILL CONTINUE OVER THE WEEKEND.
AVIATION
200300Z...COAST...LOW CLOUDS 600-900 FEET AGL DEVELOP AFTER 06Z,
WITH SOMEWHAT RANDOM COVERAGE. MOST LIKELY COVERAGE BETWEEN 10-16Z
TUESDAY, AND SCATTER OUT BY 16Z. SIMILARLY BASED CLOUDS REDEVELOP
LATE TUESDAY, SIMILAR TIMING.
INLAND...CLEAR WITH UNRESTRICTED VIS THROUGH TUESDAY.
MARINE
NO HAZARDOUS MARINE CONDITIONS EXPECTED THROUGH SATURDAY.
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...PG
AVIATION/MARINE...WESTERINK
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