599
FXUS66 KSGX 290954
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
254 AM PDT SUN MAR 29 2026
SYNOPSIS
CONTINUED HOT WEATHER TODAY WITH HIGH TEMPERATURES 15-20 DEGREES
ABOVE NORMAL INLAND. COOLER, WINDIER, AND CLOUDIER CONDITIONS
EXPECTED FOR THE MIDDLE OF NEXT WEEK. SLIGHT CHANCE (15-20
PERCENT) OF LIGHT PRECIPITATION ON WEDNESDAY FOR AREAS ALONG AND
WEST OF THE MOUNTAINS. DRIER AND WARMER CONDITIONS FOR THE END OF
NEXT WEEK WITH POTENTIAL FOR SANTA ANA WINDS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
MARINE LAYER LOW CLOUDS AND FOG ARE VERY PATCHY THIS MORNING. FOG
MAY BECOME LOCALLY DENSE WHERE SUFFICIENT RADIATIONAL COOLING
OCCURS, BUT THIS WILL BE LIMITED GIVEN THE HIGH CLOUD COVERAGE.
THE UPPER LEVEL RIDGE ACROSS THE SOUTHERN TIER OF THE US WEAKENS
SLIGHTLY TODAY, THOUGH THIS RESULTS IN MINIMAL CHANGES TO HIGH
TEMPERATURES. HIGHS WILL ONCE AGAIN BE AROUND 15-20 DEGREES ABOVE
NORMAL ACROSS THE REGION, WITH THE GREATEST DEPARTURE FROM NORMAL
IN THE VALLEYS AND LOWER ELEVATION MOUNTAINS. A COASTAL EDDY
DEVELOPS TONIGHT FOR MORE ORGANIZED LOW CLOUDS AND FOG, THOUGH THE
MARINE LAYER REMAINS FAIRLY SHALLOW, LIMITING LOW CLOUDS AND FOG
TO THE COASTAL AREAS. CONVECTION OVER THE SONORAN DESERT THIS
AFTERNOON AND EVENING COULD PRODUCE A VERY EARLY SEASON GULF SURGE
INTO THE LOW DESERTS. THE REFS HAS A 70-80% CHANCE OF DEW POINTS
OF 60F OR HIGHER OVER THE SOUTHEASTERN COACHELLA VALLEY. IF THIS
OCCURS WE COULD SEE SOME LOW CLOUDS AND LIGHT FOG IN THIS AREA
MONDAY MORNING, OR AT A MINIMUM SOME MUGGY CONDITIONS UNTIL THE
MOISTURE MIXES OUT IN THE AFTERNOON.
THE UPPER LEVEL HIGH SHIFTS MUCH FURTHER EAST ON MONDAY WITH
WEAKLY CYCLONIC FLOW DEVELOPING ACROSS CALIFORNIA. THIS BRINGS
GREATER COOLING WITH HIGHS CLOSER TO 10-15 DEGREES ABOVE NORMAL
INLAND AND AROUND 5-10 DEGREES ABOVE NORMAL NEAR THE COAST. MONDAY
COULD BE THE FIRST TIME IN TWO WEEKS THAT NO RECORD HIGH
TEMPERATURES ARE BROKEN. GREATER COOLING OCCURS TUESDAY AND
WEDNESDAY AS A WEAK TROUGH MOVES THROUGH, AND HIGH TEMPERATURES
WILL FINALLY RETURN TO NORMAL. THE MARINE LAYER DEEPENS THROUGH
THIS PERIOD WITH LOW CLOUDS EXTENDING INTO THE VALLEYS TUESDAY AND
WEDNESDAY MORNING. ENSEMBLES CONTINUE TO TREND DRIER WITH THIS
SYSTEM, ESPECIALLY OVER THE SOUTHERN PART OF THE FORECAST AREA.
FOR WEDNESDAY, THERE IS AROUND A 15% CHANCE OF 0.10" OR MORE FOR
THE COASTAL AREAS AND VALLEYS, AND A 20-25% CHANCE OVER THE
MOUNTAINS. AT THIS RATE, THE COASTAL AREAS AND VALLEYS WILL BE
LUCKY TO SEE A FEW HUNDREDTHS. WEST WINDS STRENGTHEN TUESDAY AND
WEDNESDAY ACROSS THE MOUNTAINS AND DESERTS WITH GUSTS AROUND 40-55
MPH ON THE WIND-PRONE DESERT MOUNTAIN SLOPES AND PASSES.
ON THURSDAY, AN UPPER LEVEL CLOSED LOW MOVES EAST ACROSS THE PAC
NW WITH TROUGHING CONTINUING OVER SO CAL. THIS WILL MAINTAIN
COOLER WEATHER WITH A DEEP MARINE LAYER AND BREEZY ONSHORE WINDS.
THE TROUGH ASSOCIATED WITH THIS LOW DIGS THROUGH THE GREAT BASIN
INTO THE ROCKIES ON FRIDAY WITH SURFACE HIGH PRESSURE DEVELOPING
IN ITS WAKE. WHILE THERE IS GOOD ENSEMBLE AGREEMENT WITH THE
GENERAL PATTERN, THE DEPTH OF THE TROUGH VARIES BETWEEN MEMBERS
WHICH RESULTS IN SOME UNCERTAINTY IN THE STRENGTH OF THE SANTA ANA
WINDS. THE CW3E WRF ENSEMBLE HAS AROUND A 20% CHANCE OF A WEAK
EVENT ON FRIDAY. SURFACE PRESSURE GRADIENTS REMAIN OFFSHORE INTO
SATURDAY AND AN UPPER LEVEL RIDGE BUILDS IN FROM THE WEST,
RESULTING IN MUCH WARMER AND DRIER WEATHER.
AVIATION
290945Z...PATCHY FOG IS DEVELOPING IN SD CO. COASTAL AREAS,
INCLUDING ELEVATED COASTAL MESAS UP TO 600 FT ELEVATION. VIS DOWN TO
1/4SM IN FG AND 4-6SM IN VCFG/BR. AROUND 50% CHANCE FOR PERIODS OF
VIS BELOW 1SM AND FG AT KSAN/KCRQ. LOWER CONFIDENCE IN FG
DEVELOPMENT IN OC COASTAL AREAS; TIMING LIKELY AFTER 12Z. CLEARING
EXPECTED 16-18Z. LOW CLOUDS RETURN TO THE COAST WITH HIGHER BASES,
5000-1000 FT MSL, AROUND 06-10Z MON.
OTHERWISE, PARTLY CLOUDY SKIES WITH CLOUDS AOA 20K FT MSL THROUGH
THE TAF PERIOD.
MARINE
NO HAZARDOUS MARINE CONDITIONS EXPECTED THROUGH WEDNESDAY.
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...SS
AVIATION/MARINE...WESTERINK
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