708
FXUS66 KSGX 250938
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
238 AM PDT MON AUG 25 2025
SYNOPSIS
DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH
THE MIDDLE OF THE WEEK AS THE MONSOON WEATHER PATTERN CONTINUES
ACROSS THE MOUNTAINS AND DESERTS, ALTHOUGH THIS WILL BE WINDING
DOWN GOING INTO THE LATER PART OF THE WEEK AND INTO THE WEEKEND,
WITH A LESSER CHANCE OF AFTERNOON THUNDERSTORMS. INLAND VALLEYS
MAY SEE A STORM OR TWO THIS AFTERNOON, OTHERWISE ALL AREAS WILL
REMAIN HUMID THROUGH THE EARLY PART OF THE WEEK. A COOLING TREND
WILL BEGIN TOMORROW AND CONTINUE THROUGH WEDNESDAY, THEN REMAIN
NEARLY STEADY THROUGH THE WEEKEND. A WEAK TROUGH OFFSHORE WILL
HELP TO LOWER CHANCES FOR MONSOONAL STORM ACTIVITY ACROSS THE
MOUNTAINS AND DESERTS BY THE MIDDLE OF THE WEEK WITH LESS HUMID
CONDITIONS. THE MARINE LAYER WILL BE OF SIMILAR DEPTH OVER THE
NEXT FEW DAYS WITH PATCHY FOG NEAR THE COAST, PUSHING FURTHER
INLAND BY THE END OF THE WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
TODAY THROUGH TONIGHT...
THE SUBTROPICAL RIDGE CONTINUES TO DOMINATE THE REGION WITH ABOVE
AVERAGE TEMPERATURES AND RECYCLED MONSOONAL MOISTURE IN THE MID TO
UPPER LEVELS WILL ALSO AGAIN PROVIDE A CHANCE OF THUNDERSTORMS OVER
THE MOUNTAINS AND DESERTS DURING THE AFTERNOON AND EARLY EVENING
HOURS. GIVEN THE VERY WEAK FLOW OUT OF THE SOUTH AT THE 700 MB
LEVEL, IT IS LIKELY THAT ANY SHOWERS AND STORMS THAT DEVELOP LATER
TODAY OVER THE HIGHER TERRAIN DUE TO OROGRAPHIC LIFTING WILL
STRUGGLE TO MOVE OFF INTO THE ADJACENT VALLEYS AND DESERTS. THERE IS
STILL ENOUGH INSTABILITY OVER THE DESERTS TO ALLOW FOR ANOTHER
POSSIBLE STRONG STORM, SIMILAR AS TO WHAT THERE WAS YESTERDAY
OVER IMPERIAL. BASES OF ASSOCIATED CBS WITH THESE STORMS WILL BE
QUITE ELEVATED WITH THE CLASSIC "INVERTED V" SOUNDING, SIGNIFYING
A LOT OF DRIER AIR ALOFT AND DCAPE ALLUDES TO THE POSSIBILITY OF
SOME OF THESE STORMS PRODUCING GUSTY OUTFLOW WINDS DUE TO DRY
MICROBURSTS. THERE COULD ALSO BE SOME SMALL HAIL, ESPECIALLY OVER
THE DESERTS WHERE THERE ARE HIGHER MUCAPE VALUES. THERE COULD ALSO
BE BRIEF PERIODS OF HEAVY RAIN, SMALL HAIL, DANGEROUS CLOUD-TO-
GROUND LIGHTNING, AND GUSTY AND ERRATIC WINDS, REGARDLESS IF THERE
ARE ANY DRY MICROBURSTS PRODUCED. THERE EVEN EXISTS THE SLIGHT
CHANCE OF A "HEAT BURST" HAPPENING AGAIN, SIMILAR TO WHAT HAPPENED
A COULD OF DAYS AGO WITH THE INLAND VALLEYS BECOMING MUCH WARMER
THAN SURROUNDING AREAS, GIVEN THE AMOUNT OF DRY AIR ALOFT AND THE
PRESENCE OF A STRONG INVERSION WEST OF THE MOUNTAIN RANGES.
TEMPERATURES WILL BE SIMILAR TODAY, PERHAPS A DEGREE OR TWO COOLER
FOR SOME LOCATIONS. THE MARINE LAYER WILL LIKELY REMAIN PARTIALLY
ERODED OUT FROM OVER THE INNER COASTAL WATERS THIS MORNING AS IT
CURRENTLY IS DUE TO MID LEVEL CLOUDS PASSING OVERHEAD. THERE COULD
BE SOME PATCHY AREAS OF FOG THIS MORNING, ESPECIALLY WITHIN SOME
OF THE VALLEYS ALONG THE I-15 CORRIDOR.
TOMORROW THROUGH THE UPCOMING WEEKEND...
FOR TOMORROW, THE SUBTROPICAL RIDGE AXIS WILL BEGIN TO SHIFT MORE
TOWARDS THE EAST AND ALLOW FOR TROUGHING UPSTREAM FROM THE NORTHWEST
TO BEGIN TO EDGE CLOSER TO SOCAL EVER SO SLOWLY AND BEGIN A GRADUAL
COOLDOWN THAT WILL CONTINUE THROUGH THE REST OF THE WEEK, WITH
TEMPERATURES RETURNING TO MORE NORMAL VALUES TOMORROW. THE MONSOON
MOISTURE WILL BECOME MORE CONFINED TO THE EAST, ALTHOUGH THERE COULD
BE AN ISOLATED STORM OR TWO STILL DEVELOPING OVER THE MOUNTAINS AND
POSSIBLY THE ADJACENT DESERTS TOMORROW DURING THE AFTERNOON HOURS,
OTHERWISE TOMORROW WILL BEGIN A DRYING TREND WITH A LESSER CHANCE OF
MOUNTAIN/DESERT THUNDERSTORMS GOING INTO THE LATTER PART OF THE
WEEK. TEMPERATURES WILL BE COOLER TOMORROW, AND CLOSER TO THE
SEASONAL AVERAGE FOR THIS TIME OF YEAR, AND THEN TEMPERATURES WILL
REMAIN NEARLY STEADY THROUGHOUT THE REST OF THE WEEK AND GOING INTO
THE WEEKEND. MOST OF THE DETERMINISTIC MODELS KEEP A VERY SLIGHT
CHANCE OF CONVECTION OVER THE MOUNTAINS/DESERTS DURING THE AFTERNOON
HOURS, ALTHOUGH IT WILL LIKELY BE ONLY OVER A FEW ISOLATED AREAS
WHERE THERE IS HIGHER TERRAIN, SUCH AS THE SAN BERNARDINO MOUNTAINS.
THE CWA SHOULD BE MOSTLY DRY AND CLEAR FOR THE UPCOMING WEEKEND.
THE MARINE LAYER WILL BEGIN TO DEEPEN AND EXTEND FURTHER INLAND
OVERNIGHT WITH A MORE PERSISTENT ONSHORE FLOW BY LATER IN THE
WEEK.
AVIATION
250900Z...COAST/VALLEYS...PATCHY LOW CLOUDS BASED 800-1100 ALONG THE
IMMEDIATE COAST WILL MOVE INLAND LOCALLY TO 5-10 MI. CIGS LIKELY TO
LOWER A TAD TOWARDS 12Z TO 700-1000 FT MSL. 50-60% CHANCE FOR CIGS
AT KCRQ 12-16Z AND 40% CHANCE FOR BRIEF CIGS AT KSNA 14-15Z. LOCAL
VIS 3-6 SM IN BR WHERE STRATUS OCCURS, ISOLATED BELOW 1 SM OVER
HIGHER COASTAL AND WESTERN VALLEY TERRAIN. CLOUDS AND VIS
RESTRICTIONS CLEARING 15-17Z. CLOUDS REDEVELOPING AFTER 26/04Z WITH
BASES AROUND 900-1200 FT MSL.
MOUNTAINS/DESERTS...50-70% CHANCE OF +SHRA/TSRA OVER THE MOUNTAINS
AND A 35-50% CHANCE OVER THE DESERTS BETWEEN 19-02Z. CB BASES NEAR
12 KFT AND TOPS TO 30 KFT. GUSTY OUTFLOW WINDS OF 35 KT OR MORE, 1-3
SM VIS IN +RA, SMALL HAIL, AND LIGHTNING ARE POSSIBLE. CB/SHRA
DISSIPATING THIS EVENING.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH FRIDAY.
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...STEWEY
AVIATION/MARINE...CSP
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