319
FXUS66 KSGX 262055
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
155 PM PDT TUE AUG 26 2025
SYNOPSIS
MONSOONAL MOISTURE WILL ONCE AGAIN BE PRESENT TODAY WITH SCATTERED
SHOWERS AND THUNDERSTORMS ACROSS THE MOUNTAINS AND DESERTS, WITH
LOCALLY HEAVY RAINFALL AND GUSTY WINDS. CHANCES FOR STORMS WILL
DECREASE ACROSS THIS AREA BY WEDNESDAY. MID AND HIGH LEVEL
MOISTURE FROM THE REMNANTS OF TROPICAL STORM JULIETTE COULD BRING
SOME SCATTERED SHOWERS AND ON THURSDAY TO MUCH OF THE REGION. A
DRYING AND WARMING TREND WILL OCCUR BY THE END OF THIS WEEK,
INCLUDING LESS HUMID DAYS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
THUNDERSTORMS ARE BEGINNING TO DEVELOP ACROSS THE MOUNTAINS INTO
THE HIGH DESERT THIS AFTERNOON. THESE STORMS WILL BE ACCOMPANIED
BY HEAVY RAIN, GUSTY WINDS AND SMALL HAIL. LIKE YESTERDAY, THE
BEST CHANCE FOR AREAS TO GET RAIN WILL BE ACROSS THE DESERT SLOPES
INTO THE DESERTS. RAIN RATES FROM HI-RES MODELS SHOW HIGHEST RATES
NEAR THREE QUARTERS TO LOCALLY ONE INCH PER HOUR RATES. STORMS
WILL LAST THROUGH EARLY EVENING BEFORE TAPERING OFF. MONSOONAL
MOISTURE WILL DECREASE BY WEDNESDAY AS PWAT VALUES LOWER CLOSER TO
1.25" ACROSS THE LOWER DESERTS AND MID LEVEL WINDS TURN WESTWARD.
HI-RES MODELS SHOW MUCH LESS STORM COVERAGE BY WEDNESDAY
AFTERNOON, WITH THE MAIN FOCUS ACROSS THE SAN DIEGO AND RIVERSIDE
COUNTY MOUNTAINS WHERE RAIN RATES WILL BE MAINLY BELOW ONE HALF
INCH.
AN INTERESTING FORECAST UNFOLDS BY WEDNESDAY NIGHT INTO THURSDAY
AS REMNANTS FROM TROPICAL STORM JULIETTE MOVES NORTH PARALLEL TO
THE BAJA CALIFORNIA COAST. THIS WILL BRING IN HIGH CLOUDS TO
ACROSS THE REGION. FORECAST SOUNDINGS AND MODEL DATA SHOW A MOIST
ATMOSPHERIC PROFILE, THOUGH THE LOWER THIRD OF THE ATMOSPHERE HAS
ADEQUATE T/TD SPREAD, SHOWING DRIER AIR NEAR THE SURFACE. THE
BEST CHANCES FOR RAINFALL TO REACH THE GROUND WILL BE PLACES
ACROSS SAN DIEGO COUNTY, WHERE ENSEMBLE MODEL MEMBERS ARE SHOWING
SOME LIGHT PRECIP AMOUNTS. LIGHT SHOWERS WILL BE POSSIBLE ACROSS
MUCH OF THE AREA, MINUS THE HIGH DESERT. THURSDAY WILL SEE MOSTLY
CLOUDY SKIES FOR MUCH OF THE REGION AS THE TROPICAL MOISTURE MOVES
IN, SO THIS WILL BE THE COOLEST DAY OF THE WEEK WITH SOME PLACES
ACROSS THE LOWER DESERTS STAYING BELOW 100 DEGREES.
HIGH PRESSURE OVER THE DESERT SOUTHWEST WILL PUSH SOUTHWARD INTO
NORTHERN MEXICO BY FRIDAY AS A WEAK TROUGHING PATTERN SETS UP
ACROSS CALIFORNIA. PWATS LOWER WITH MINOR INSTABILITY PRESENT, SO
ANY STORMS THAT FORM WOULD DO SO OVER THE MOUNTAINS WITH A 15-25%
CHANCE OF OCCURRENCE. FURTHER DRYING IS EXPECTED BY FRIDAY INTO
THE WEEKEND WITH MINIMAL CHANCES FOR STORMS ACROSS THE REGION. THE
AREA OF HIGH PRESSURE OF NORTHERN MEXICO WILL ALSO BEGIN TO EXPAND
WESTWARD, WHERE SOUTHERN CALIFORNIA WILL SEE A SUBTLE WARMING
TREND WITH LOWER HUMIDITY BY THE END OF THE WEEK.
AVIATION...262045Z...COAST/WESTERN VALLEYS
ISOLATED LOW CLOUDS
1000-1300 FT MSL ALONG THE IMMEDIATE COAST WILL START TO BECOME MORE
WIDESPREAD AND MOVE INLAND 04-06Z. RESTRICTED VIS 2-5 SM FOR HIGHER
TERRAIN IN WESTERN VALLEYS. CLOUDS CLEAR BACK TO BEACHES 15-17Z WED
MORNING.
MOUNTAINS/DESERTS...ISOLATED +SHRA/TSRA THROUGH 01Z WITH CB BASES
AROUND 10 KFT, MOSTLY CONFINED TO THE MOUNTAINS AND HIGH DESERT.
GUSTY AND ERRATIC WINDS OF 35 KTS OR GREATER, 1-3 SM VIS IN +RA,
SMALL HAIL, AND LIGHTNING ARE POSSIBLE. 40-50% CHANCE OF TSRA VCNTY
KPSP AND KTRM UNTIL 01Z.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH SUNDAY.
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...APR
AVIATION/MARINE...WESTERINK
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