671
FXUS66 KSGX 232347
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
447 PM PDT WED SEP 23 2026
SYNOPSIS
WARMER CONDITIONS THROUGH SATURDAY WITH MODERATE HEATRISK FOR THE
COAST AND WESTERN VALLEYS ON FRIDAY AND SATURDAY. NIGHT AND MORNING
LOW CLOUDS AND FOG WILL STAY CONFINED TO THE COASTAL AREAS FOR THE
NEXT FEW NIGHTS. THERE IS A A SLIGHT CHANCE OF SHOWERS AND ISOLATED
THUNDERSTORMS OVER THE MOUNTAINS THURSDAY AFTERNOON. COOLER
CONDITIONS EXPECTED SUNDAY AND MONDAY, WITH POTENTIALLY WARMER
CONDITIONS NEXT TUESDAY.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
..UPDATED AVIATION DISCUSSION
TEMPERATURES AT 1 PM WERE RUNNING 10 TO 18 DEGREES WARMER THAN
YESTERDAY IN THE INLAND EMPIRE, 5 TO 7 DEGREES WARMER THAN YESTERDAY
FOR OTHER INLAND LOCATIONS, AND WERE WITHIN A FEW DEGREES OF
YESTERDAY FOR THE COAST. MOST LOCATIONS WILL SEE AN INCREASE IN
TEMPERATURES EACH DAY THROUGH SATURDAY, WITH HIGH TEMPERATURES 5 TO
7 DEGREES ABOVE AVERAGE FOR INLAND LOCATIONS AND 7 TO 12 DEGREES
ABOVE AVERAGE FOR THE COAST. OVERNIGHT LOWS WILL INCREASE TO THE MID-
60S TO 70 WEST OF THE MOUNTAINS AND IN THE UPPER 70S TO LOW 80S IN
THE LOW DESERT. MODERATE HEATRISK IS EXPECTED ALONG THE COAST FRIDAY
AND SATURDAY AND IN THE LOW DESERTS FOR THE SECOND HALF OF THE WEEK.
MODERATE HEATRISK HAS THE MOST IMPACTS ON THOSE SENSITIVE TO HEAT,
ESPECIALLY THOSE WITHOUT COOLING/HYDRATION.
FOR THURSDAY, A CLOSED LOW LINGERING TO OUR SOUTH WILL START TO
MOVE EAST. THIS LOW WILL DRAW MOISTURE INTO SOUTHERN CALIFORNIA
FROM THE SOUTHEAST INCREASING CHANCES FOR PRECIPITATION, MAINLY IN
THE MOUNTAINS. LATEST HIGH RESOLUTIONS GUIDANCE INDICATES
RAINFALL RATES WILL MOSTLY BE 0.20-0.30 INCHES PER HOUR, WHERE
THUNDERSTORMS DEVELOP RATES COULD BE CLOSER TO 0.50 INCHES PER
HOUR. THERE REMAINS A 5-10% CHANCE OF THUNDERSTORMS OVER THE
MOUNTAINS WITH THE HIGHER CHANCES OVER THE SAN DIEGO AND RIVERSIDE
COUNTY MOUNTAINS.
FOR SUNDAY, AN INCOMING TROUGH OF LOW PRESSURE IS EXPECTED TO MOVE
INLAND ACROSS NORTHERN CALIFORNIA. THE LOW WILL DIG SOUTH MONDAY AND
BE TO OUR EAST TUESDAY OR EARLY WEDNESDAY. THERE IS GOOD AGREEMENT
THAT TEMPERATURES WILL COOL 3 TO 8 DEGREES BETWEEN SATURDAY AND
SUNDAY AND ANOTHER 2 TO 4 DEGREES FOR MONDAY. ADDITIONALLY CLOUD
COVERAGE WILL INCREASE. THE TROUGH LOOKS LIKE IT WILL PULL IN
MOISTURE FROM OUR SOUTHWEST, BUT THERE REMAINS UNCERTAINTY IN HOW
MUCH MOISTURE WILL ACTUALLY GET PULLED INTO SOUTHERN CALIFORNIA.
ENSEMBLE MEMBERS FROM BOTH THE GFS AND ECMWF ARE SHOWING INCREASES
IN PRECIPITABLE WATER AND SOME POTENTIAL FOR PRECIPITATION.
FOR NEXT TUESDAY AND WEDNESDAY, THE FORECAST SOLUTIONS DIVERGE WITH
60% OF SOLUTIONS SHOWING RIDGING AND 40% MAINTAINING WEAK TROUGHING.
CURRENT FORECAST FOLLOWS THE NBM AND SHOWS A FEW DEGREES OF WARMING
EACH DAY TUESDAY AND WEDNESDAY.
AVIATION
240000Z...COAST/VALLEYS...LOW CLOUDS BASED NEAR 1500 FT MSL ARE
DEVELOPING OVER COASTAL SAN DIEGO COUNTY CURRENTLY. CLOUDS SPREAD
NORTHWARD (INTO ORANGE COUNTY) AND INLAND OVERNIGHT REACHING ABOUT
15 MILES INLAND BY 10-12Z THU. BASES MAY LOWER A FEW HUNDRED FEET
OVERNIGHT WITH MINOR VIS REDUCTIONS (2-6SM) FOR ELEVATED INLAND
VALLEYS. CLOUDS SCATTER TOWARD THE COASTLINE 16-18Z.
MOUNTAINS/DESERTS
SCT CU BASED NEAR 12 KFT EXPECTED OVER MTNS
20Z THU - 01Z FRI ALONG WITH ISO SHRA/TSRA. ANY STORM THAT DEVELOPS
WILL BE CAPABLE OF PRODUCING UP/DOWNDRAFTS, LIGHTNING, AND VIS
REDUCTIONS.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH MONDAY.
BEACHES
THE COMBINATION OF A 3 FOOT SWELL FROM 190 DEGREES ON SUNDAY
SHIFTING TO 160 DEGREES FOR MONDAY AND TUESDAY WITH A 12 TO 15
SECOND PERIOD COINCIDING WITH OUR BIMONTHLY ELEVATED HIGH TIDES WILL
INCREASE CHANCES FOR COASTAL FLOODING AND EROSION. PREDICTED HIGH
TIDES OF 6.5 AND 7.0 FT MSL WILL OCCUR BETWEEN 10 AND 11 AM SUNDAY
THROUGH TUESDAY. THE LISTED TIDE PREDICTIONS HAVE BEEN CORRECTED TO
REFLECT CURRENT TRENDS IN ACTUAL TIDE OBSERVATIONS. SURF WILL BE
ELEVATED, ESPECIALLY FOR SOUTH FACING BEACHES WITH SETS UP TO 5 FEET
ON SUNDAY. SURF HEIGHTS AND DIRECTION OF THE SWELL REMAIN UNCERTAIN
FOR MONDAY AND TUESDAY AND WILL BE MOST INFLUENCED BY THE TRACK OF
TROPICAL CYCLONE POLO.
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...CO
AVIATION/MARINE/BEACHES...KW
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