303
FXUS66 KSGX 280933
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
233 AM PDT FRI AUG 28 2026
SYNOPSIS
HEAT CONTINUES TODAY WITH HIGH AND LOW TEMPERATURES WELL ABOVE
NORMAL. SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FOR THE
MOUNTAINS AND LOCALLY INTO THE DESERTS THIS AFTERNOON. GRADUAL
COOLING THIS WEEKEND WITH TEMPERATURES FALLING BELOW NORMAL BY
EARLY NEXT WEEK. FOR TUESDAY AND WEDNESDAY OF NEXT WEEK, INCREASED
HIGH CLOUD COVER IS LIKELY ALONG WITH A 20 TO 30 PERCENT CHANCE
OF LIGHT PRECIPITATION AS MOISTURE FROM TROPICAL STORM KARINA
POTENTIALLY GETS PULLED NORTHWARD. THIS TROPICAL SYSTEM IS
FORECAST TO REMAIN WELL TO OUR SOUTH.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SCATTERED HIGH CLOUDS AHEAD OF THE TROUGH OFF THE WEST COAST
CONTINUE TO DRIFT NORTHEAST OVER THE AREA THIS MORNING. PATCHES OF
LOW CLOUDS AND FOG ARE DEVELOPING OVER THE SAN DIEGO COUNTY
COASTAL AREAS. FOG MAY BECOME LOCALLY DENSE TOWARDS SUNRISE,
ESPECIALLY ON THE COASTAL MESAS. ANY LOW CLOUDS AND FOG SHOULD
QUICKLY CLEAR OUT BY MID-MORNING.
ONE LAST DAY OF EXCRUCIATING HEAT IS IN STORE WITH HIGH
TEMPERATURES AROUND 5 TO 10 DEGREES ABOVE NORMAL. WITH FAR LESS
CLOUD COVER THAN YESTERDAY AND MINIMAL COOLING THIS MORNING, IT
WILL BE SEVERAL DEGREES WARMER THAN WHAT ENDED UP OCCURRING
YESTERDAY, ESPECIALLY ACROSS THE LOW DESERTS. THE HEAT ADVISORIES
AND EXCESSIVE HEAT WARNINGS ALL REMAIN IN EFFECT THROUGH 8 PM THIS
EVENING. MODEST MID-LEVEL MOISTURE REMAINS FOR A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS OVER THE MOUNTAINS THIS AFTERNOON. WITH
FLOW ALOFT TURNING MORE SOUTHWESTERLY, A FEW OF THESE STORMS COULD
DRIFT INTO THE LOW DESERT.
THE UPPER LEVEL HIGH BEGINS TO PROGRESS EASTWARD AS AN UPPER
TROUGH PUSHES INTO THE WEST COAST ON SATURDAY. THIS WILL BRING A
FEW DEGREES OF COOLING ACROSS THE AREA, THOUGH UNFORTUNATELY THE
HUMIDITY WILL STICK AROUND. THIS TROUGH WILL REMAIN SOMEWHAT
STATIONARY THROUGH EARLY NEXT WEEK AS MULTIPLE SHORT WAVES MOVE
THROUGH THE MEAN FLOW TO OUR NORTH. THIS WILL CONTINUE THE COOLING
TREND INTO AT LEAST TUESDAY. BY SUNDAY, HIGH TEMPERATURES WILL
FINALLY RETURN TO NORMAL, THOUGH THE HUMIDITY WILL KEEP MINIMUM
TEMPERATURES AROUND 5 DEGREES ABOVE NORMAL. BY TUESDAY, HIGHS WILL
BE AROUND 5 TO 10 DEGREES BELOW NORMAL. SUBTLE DRYING ALSO ALLOWS
LOW TEMPERATURES TO RETURN TO NEAR NORMAL.
FOR LATE TUESDAY INTO THURSDAY, THERE'S AROUND A 15% CHANCE OF
MOISTLY LIGHT SHOWERS AS MID AND UPPER LEVEL MOISTURE FROM WHAT IS
CURRENTLY TROPICAL STORM KARINA POTENTIALLY GETS DRAWN NORTH. HOW
MUCH MOISTURE WE GET AND ANY FORCING THAT GOES ALONG WITH IT WILL
BE VERY SENSITIVE TO THE TRACK OF THE TROPICAL CYCLONE AS WELL AS
THE POSITION OF THE UPPER TROUGH OFF THE WEST COAST. THERE IS A
LOT OF SPREAD IN THE FORECAST PRECIPITABLE WATER FROM THE
ENSEMBLES, AND TO A GREATER EXTENT THE AMOUNT OF RAINFALL WE COULD
GET FROM IT. IT SHOULD BE NOTED THAT THE OFFICIAL NHC TRACK
FORECAST FOR THIS CYCLONE REMAINS WELL TO OUR SOUTH, SO THESE
SMALL RAIN CHANCES AND INCREASED SURF ARE THE ONLY IMPACT WE ARE
ANTICIPATING FROM THIS SYSTEM.
MINOR WARMING IS POSSIBLE LATE IN THE WEEK AS HIGH PRESSURE TRIES
TO EXPAND WESTWARD AGAIN, THOUGH THE WARMEST ENSEMBLE SOLUTIONS
ONLY ACCOUNT FOR ABOUT 40% OF THE ENSEMBLE SPACE AT THIS POINT,
WITH THE REMAINING 60% KEEPING TEMPERATURES CLOSER TO MIDWEEK
VALUES.
AVIATION
280930Z...COAST...LOW CLOUDS BASED 400-700 FT MSL WILL CONTINUE TO
BECOME MORE WIDESPREAD THROUGH COASTAL SD COUNTY, AS MID TO UPPER
LEVEL CLOUDS MOVE NORTHWARDS OUT OF THE AREA, THOUGH LIKELY WILL
REMAIN PATCHY FOR MOST OF THE NIGHT. BEST CHANCES FOR IMPACTS FOR
COASTAL SITES IS THROUGH 15Z, WITH VIS RESTRICTIONS 2-5 SM OVER
HIGHER COASTAL TERRAIN. LOW CLOUDS EXPECTED TO CLEAR BY 16Z, WITH
LOW CLOUDS OF SIMILAR BASES/PATCHINESS FORMING AFTER 09Z SAT.
MOUNTAINS/DESERTS...CUMULUS BASED AROUND 9,000FT MSL OVER THE
MOUNTAINS TODAY 20Z TO SAT 01Z WITH ISOLATED CB CLOUD TOPS RISING TO
40,000FT MSL. THERE IS A 10-15% CHANCE OF ISO TSRA/SHRA OVER THE
MOUNTAINS AND A 5-10% CHANCE IN THE DESERTS UNTIL 01Z SAT. ANY TS
THAT DEVELOPS COULD PRODUCE GUSTY, ERRATIC WINDS.
REGIONWIDE...HIGH CLOUDS AOA 15,000FT MSL WILL CONTINUE THIS
MORNING AND AFTERNOON, DECREASING THROUGH THIS EVENING.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH TUESDAY.
BEACHES
A FRESH 3 FOOT SWELL FROM THE SOUTH-SOUTHWEST (200 DEGREES) AT 15-17
SECONDS MOVES INTO THE REGION SATURDAY-SUNDAY. THIS WILL BRING
LOCALIZED ELEVATED SURF OF 4-6 FEET TO SOUTHWEST-FACING BEACHES,
MOSTLY IN NORTH SAN DIEGO COUNTY AND ORANGE COUNTY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR ORANGE COUNTY
COASTAL AREAS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO
COUNTY MOUNTAINS-SAN DIEGO COUNTY COASTAL AREAS.
EXTREME HEAT WARNING UNTIL 8 PM PDT THIS EVENING FOR APPLE AND
LUCERNE VALLEYS-COACHELLA VALLEY-ORANGE COUNTY INLAND AREAS-
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND
EMPIRE-SAN DIEGO COUNTY DESERTS-SAN DIEGO COUNTY MOUNTAINS-
SAN DIEGO COUNTY VALLEYS-SAN GORGONIO PASS NEAR BANNING-
SANTA ANA MOUNTAINS AND FOOTHILLS.
PZ...NONE.
PUBLIC...SS
AVIATION/MARINE/BEACHES...CSP
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