024
FXUS66 KSGX 281907
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
1207 PM PDT FRI AUG 28 2026
SYNOPSIS
ABOVE AVERAGE HIGH AND LOW TEMPERATURES WILL CONTINUE INTO SATURDAY.
THERE IS A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IN THE
MOUNTAINS AND LOCALLY INTO THE DESERTS THIS AFTERNOON. BY SUNDAY,
TEMPERATURES WILL RETURN TO BELOW AVERAGE FOR THIS TIME OF YEAR. 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...
WEST OF THE MOUNTAINS, TEMPERATURES AT NOON WERE RUNNING 3 TO 8
DEGREES WARMER THAN THIS TIME YESTERDAY, LIKELY DUE TO THE
DECREASED HIGH CLOUD COVERAGE TODAY. LOW TEMPERATURES THIS MORNING
STARTED OFF IN THE LOW TO MID 70S FOR THE COAST AND WESTERN
VALLEYS, FURTHER INLAND LOWS WERE IN THE UPPER 70S TO LOW 80S. THE
WARMEST CONDITIONS OVERNIGHT WERE IN THE LOW DESERTS WHERE
TEMPERATURES OVERNIGHT ONLY FELL TO THE UPPER 80S OR LOW 90S.
LINGERING MID-LEVEL MOISTURE WILL BRING A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS OVER THE MOUNTAINS THIS AFTERNOON.
SOUTHWESTERLY FLOW ALOFT MAY PUSH A FEW OF THESE STORMS INTO THE
LOW DESERT. LATEST HIGH RESOLUTION GUIDANCE SHOWS A DECREASE IN
COVERAGE COMPARED TO EARLIER RUNS, WITH PEAK RAINFALL RATES
EXPECTED TO BE 0.50-0.70 INCHES PER HOUR WHERE THUNDERSTORMS
DEVELOP.
THE UPPER LEVEL RIDGE WILL START TO GET PUSHED EAST SATURDAY AS A
TROUGH OF LOW PRESSURE MOVES INTO THE PACIFIC NORTHWEST. THIS WILL
ALLOW FOR A FEW DEGREES OF COOLING FOR AFTERNOON HIGHS, BUT
OVERNIGHT LOWS WILL REMAIN ELEVATED CONTINUING TO LIMIT OVERNIGHT
RELIEF FROM THE HEAT. WIDESPREAD MODERATE TO LOCALLY MAJOR
HEATRISK WILL PREVAIL FOR THE COAST, VALLEYS, AND SAN DIEGO
MOUNTAINS. MAJOR HEATRISK WILL BE MAINTAINED INTO SATURDAY FOR
THE LOW DESERTS. GIVEN THE SLOWER COOLING, THE HEAT PRODUCTS FOR
THE AREAS MENTIONED ABOVE HAVE BEEN EXTENDED INTO SATURDAY. THE
TROUGH WILL BE THE MAIN INFLUENCE OVER OUR WEATHER BY SUNDAY,
BRINGING COOLER CONDITIONS WITH INCREASED MARINE LAYER CLOUD
COVERAGE AND AN UPTICK IN WESTERLY WINDS. BOTH HIGH AND LOW
TEMPERATURES WILL FINALLY FALL BELOW AVERAGE.
FOR NEXT WEEK, TROUGHING REMAINS THE PREVAILING PATTERN OVER THE
WEST COAST. FOR THE MIDDLE OF THE WEEK, THERE IS A POTENTIAL FOR
INCREASED CLOUDS AND LIGHT PRECIPITATION DUE TO MOISTURE FROM
TROPICAL STORM KARINA. THE CURRENT NHC TRACK KEEPS THE SYSTEM FAR
ENOUGH SOUTH WHERE THIS WILL BE THE MAIN IMPACTS FROM THE STORM
IN ADDITION TO AN INCREASE IN SURF. 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
281730Z...COAST...PATCHY LOW CLOUDS BASED 400-700 FEET MSL WILL
PERSIST ALONG SOME BEACHES. PATCHY LOW CLOUDS TO EXPAND IN COVERAGE
AFTER 06Z TONIGHT INTO SATURDAY, YET STILL NOT WIDESPREAD, UNIFORM
COVERAGE BY 13Z SATURDAY. CIGS AROUND 500-800 FEET MSL AND VIS 1-
5SM, LOWEST ON MESAS, MOST LIKELY 12-16Z SATURDAY.
MOUNTAINS/DESERTS...CUMULUS BASED AROUND 9000 FEET MSL OVER THE
MOUNTAINS WITH ISOLATED CB CLOUD TOPS RISING TO 40000 FEET MSL TODAY
20-01Z. THERE IS A 10-15% CHANCE OF TSRA/SHRA OVER THE MOUNTAINS AND
A 5-10% CHANCE IN THE DESERTS. ANY TS THAT DEVELOPS COULD PRODUCE
GUSTY, ERRATIC WINDS.
REGIONWIDE...SCT TO LOCALLY BKN HIGH CLOUDS AOA 150000 FEET MSL
TODAY, TURNING MOSTLY CLEAR TONIGHT INTO SATURDAY.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH TUESDAY.
BEACHES
A 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 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.
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 SATURDAY FOR ORANGE COUNTY COASTAL
AREAS-SAN DIEGO COUNTY COASTAL AREAS.
EXTREME HEAT WARNING UNTIL 8 PM PDT SATURDAY FOR 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.
HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR RIVERSIDE COUNTY
MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS.
EXTREME HEAT WARNING UNTIL 8 PM PDT THIS EVENING FOR APPLE AND
LUCERNE VALLEYS.
PZ...NONE.
PUBLIC...CO
AVIATION/MARINE/BEACHES...MM
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