144
FXUS66 KSGX 300819
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
119 AM PDT SUN AUG 30 2026
SYNOPSIS
GRADUAL COOLING THROUGH THE MIDDLE OF THE WEEK. FOR TUESDAY AND
WEDNESDAY, INCREASED MID AND HIGH CLOUD COVER IS LIKELY ALONG
WITH A 5 TO 15 PERCENT CHANCE OF LIGHT PRECIPITATION AS MOISTURE
FROM TROPICAL CYCLONE KARINA POTENTIALLY GETS PULLED NORTHWARD.
THIS TROPICAL SYSTEM IS FORECAST TO REMAIN WELL TO OUR SOUTH.
GRADUAL WARMING FOR THE LATTER HALF OF NEXT WEEK. NIGHT AND
MORNING LOW CLOUDS WILL BE MORE WIDESPREAD FOR THE UPCOMING WEEK,
REACHING INTO THE WESTERN VALLEYS AT TIMES.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
PATCHY LOW CLOUDS ARE DEVELOPING OVER THE COASTAL AREAS AND FAR
WESTERN VALLEYS THIS MORNING WITH JUST A FEW HIGH CLOUDS
ELSEWHERE. MARINE LAYER LOW CLOUDS WILL CONTINUE TO DEVELOP
THROUGH THE MORNING WITH THE GREATEST COVERAGE IN SAN DIEGO
COUNTY, THEN CLEAR BY LATE MORNING.
SATELLITE WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH JUST OFF
THE WEST COAST AND A WEAK SHORT WAVE MOVING THROUGH THE BAY AREA.
THIS TROUGH WILL BRING US SOME LONG-AWAITED COOLING AS HIGH
TEMPERATURES RETURN TO NEAR NORMAL TODAY. HIGHS WILL BE IN THE
LOW TO MID 80S IN THE COASTAL AREAS, UPPER 80S TO MID 90S FOR THE
WESTERN VALLEYS, MID TO UPPER 90S IN THE INLAND VALLEYS, 70S AND
80S IN THE MOUNTAINS, MID 90S IN THE HIGH DESERT, AND AROUND
100-108 IN THE LOW DESERT. NO SIGNS OF DEW POINTS DROPPING YET
FOR THE COASTAL AREAS AND LOWER ELEVATION VALLEYS THOUGH, SO
DESPITE SOME RELIEF FROM THE HEAT IT WILL REMAIN HUMID.
THE UPPER LEVEL TROUGH REMAINS IN PLACE FOR MUCH OF THE WEEK WITH
SEVERAL SHORT WAVES MOVING THROUGH THE MEAN FLOW. THIS WILL
MAINTAIN HIGH TEMPERATURES NEAR TO A FEW DEGREES BELOW NORMAL
THROUGH FRIDAY. THE MARINE LAYER REBUILDS THROUGH THIS PERIOD FOR
MORE WIDESPREAD NIGHT AND MORNING LOW CLOUDS FOR THE COASTAL AREAS
AND WESTERN VALLEYS. THE GEFS AND CANADIAN ENSEMBLES HAVE BACKED
OFF ON THE AMOUNT OF MOISTURE THAT GETS PULLED INTO SO CAL FROM
TROPICAL CYCLONE KARINA ON TUESDAY AND WEDNESDAY. WHILE WE MAY
STILL GET AN INCREASE IN MID AND HIGH CLOUDS FROM THIS SYSTEM,
PRECIPITATION CHANCES HAVE LOWERED TO AROUND 5-15%.
LATE IN THE WEEK, ENSEMBLES BEGIN TO DIVERGE ON THE PLACEMENT OF
THE UPPER TROUGH NEAR THE WEST COAST AND THE UPPER HIGH OVER THE
SOUTHERN ROCKIES, WITH A TREND TOWARDS A MORE EASTWARD PLACEMENT
OF EACH. THIS MORE EASTWARD PLACEMENT OF THE RIDGE AND TROUGHING
CLOSER TO THE COAST WOULD LIMIT THE AMOUNT OF WARMING LATE IN THE
WEEK INTO NEXT WEEKEND. THIS WOULD ALSO AFFECT THE STEERING FLOW
OF A POTENTIAL TROPICAL SYSTEM AND ANY MOISTURE AND PRECIPITATION
WE'D RECEIVE FROM IT OVER THE WEEKEND INTO EARLY NEXT WEEK. WHILE
THE NATIONAL HURRICANE CENTER HAS A 90% CHANCE OF THIS DISTURBANCE
DEVELOPING INTO A TROPICAL CYCLONE OFF THE COAST OF MEXICO IN THE
NEXT 7 DAYS, IT IS FAR TOO EARLY TO TELL WHAT, IF ANY, IMPACTS
WE'LL SEE LOCALLY, ESPECIALLY GIVEN THE ENSEMBLE SPREAD IN THE
UPPER LEVEL PATTERN. CURRENT FORECAST HAS AT LEAST A CHANCE OF
PRECIPITATION NEXT SUNDAY.
AVIATION
300600Z...COAST...PATCHY LOW CLOUDS CONTINUE NEAR THE COAST,
BECOMING MORE WIDESPREAD AND MOVING INLAND AFTER ABOUT 09Z.
INTERMITTENT CIGS AT COASTAL TAF SITES WITH HIGHEST CONFIDENCE FOR A
FEW HOURS OF IFR CIGS AT KSAN (70-80%) AND KCRQ (50%) BY 12Z. THERE
IS ONLY ABOUT A ~30% CHANCE OF CIGS REACHING COASTAL ORANGE COUNTY
(KSNA) FOR 12-16Z. BASES ARE EXPECTED TO BE AROUND 600-1000FT MSL.
VIS DOWN TO 2-5SM FOR POCKETS OF THE COAST AND VALLEYS, LOCALLY DOWN
TO 1/2SM FOR ELEVATED COASTAL TERRAIN. ANY CLOUDS THAT MOVE INLAND
WILL SCATTER BACK TO THE COAST BY 16-17Z, WITH SKC THEREAFTER.
CLOUDS WITH SLIGHTLY HIGHER BASES WILL FORM AND MOVE INTO COASTAL
REGIONS AFTER 06Z MON.
MTNS/DESERTS
OCCASIONAL FEW HIGH LVL CLOUDS AOA 20,000FT MSL
THROUGH THE PERIOD. BREEZY WEST TO SOUTHWEST WINDS 20Z SUN TO ABOUT
05Z MON ON THE DESERT SLOPES INTO THE DESERTS, WITH GUSTS TO 25-40
KTS.
MARINE
GUSTS AROUND 20 KNOTS EXPECTED EACH AFTERNOON THROUGH MONDAY IN THE
VICINITY OF SAN CLEMENTE ISLAND. OTHERWISE, NO HAZARDOUS MARINE
CONDITIONS ARE EXPECTED THROUGH THURSDAY.
BEACHES
A 3-FOOT SWELL FROM THE SOUTH-SOUTHWEST (200 DEGREES) AT 15-17
SECONDS WILL PERSIST INTO SUNDAY. THIS WILL BRING LOCALIZED ELEVATED
SURF OF 3-5 FEET WITH SETS TO 6 FEET, ALONG WITH A HIGH RIP CURRENT
RISK TO SOUTHWEST-FACING BEACHES, MOSTLY IN NORTH SAN DIEGO COUNTY
AND ORANGE COUNTY. A NEW PULSE OF SOUTHERLY SWELL (180-190 DEGREES)
FROM TROPICAL STORM KARINA WILL KEEP SURF ELEVATED AT 3-6 FEET FOR
MONDAY 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/BEACHES...CSP
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