062
FXUS66 KSGX 260420
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
920 PM PDT MON AUG 25 2025
SYNOPSIS
AFTERNOON MONSOON THUNDERSTORMS ARE POSSIBLE BOTH TUESDAY AND
WEDNESDAY, THOUGH LESS WIDESPREAD THAN MONDAY. A PATTERN CHANGE
FOR THE LATTER HALF OF THE WEEK WILL LIMIT THUNDERSTORMS AFTER
WEDNESDAY, WITH MORE SEASONABLE TEMPERATURES AND A DEEPENING
MARINE LAYER. BY THE WEEKEND AND INTO EARLY NEXT WEEK, A WARMING
TREND SETS IN AND TEMPERATURES RETURN ABOVE NORMAL.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
EVENING UPDATE...
CONVECTION IS FINALLY COMING TO AN END THIS EVENING AFTER A VERY
ACTIVE DAY. STORM REPORTS, RAINFALL TOTALS, AND LIGHTNING COUNTS
CAN BE FOUND ON OUR HOME PAGE. A WEAK JET WILL NOSE IN FROM THE
SOUTH TONIGHT WITH LINGERING ELEVATED INSTABILITY IN PLACE, WHICH
COULD PRODUCE ISOLATED LIGHT SHOWERS (20% CHANCE), MAINLY FOR THE
MOUNTAINS AND DESERTS WHERE HIGHER PW EXISTS. OTHERWISE MARINE
LAYER LOW CLOUDS WILL DEVELOP ALONG THE COAST AND SPREAD INTO THE
WESTERN VALLEYS OVERNIGHT.
ONLY REAL DEVIATION FROM PREVIOUS DISCUSSION IS THAT THERE IS THE
POTENTIAL FOR MID AND HIGH LEVEL MOISTURE FROM WHAT IS CURRENTLY
TROPICAL STORM JULIETTE TO BE PULLED INTO SO CAL SOMEWHERE AROUND
THU/FRI ALONG WITH VERY WEAK ELEVATED INSTABILITY. THIS COULD
PRODUCE SOME SPRINKLES/LIGHT SHOWERS ACROSS THE REGION WITH THE
BEST CHANCES OVER SAN DIEGO COUNTY. WILL HAVE TO WATCH THE
INSTABILITY FOR ANY ELEVATED OR NOCTURNAL THUNDERSTORM POTENTIAL.
PREVIOUS DISCUSSION...
AS AN UPPER LEVEL LOW MOVES CLOSER TO THE COAST FROM THE WEST,
THUNDERSTORM CHANCES WILL SHIFT NORTHWARD FOR TUESDAY, WITH THE
HIGHER RAIN RATES (>1"/HR) SHIFTED TOWARDS THE SAN BERNARDINO
MOUNTAINS AND HIGH DESERTS FOR TUESDAY AFTERNOON. TOMORROW LOOKS
LIKE A RINSE-AND-REPEAT OF TODAY, JUST WITH THE MAIN CORRIDOR OF
MOISTURE AND STORMS SHIFTED TOWARDS THOSE NORTHERN REGIONS. BY
WEDNESDAY, THE LOW TRANSITIONS TO AN OPEN TROUGH AND MOVES INLAND
AND MONSOONAL THUNDERSTORM CHANCES DROP FOR WEDNESDAY AND BEYOND.
TEMPERATURES THROUGH THE END OF THE WEEK HOLD STABLE, JUST AT OR
SLIGHTLY BELOW NORMAL FOR AFTERNOON HIGHS. AMPLE LINGERING
MOISTURE IN THE DESERTS AND DESERT FOOTHILLS WILL LIMIT OVERNIGHT
LOWS FROM COOLING MUCH THROUGH THE THE END OF THE WEEK, KEEPING
THINGS A BIT WARMER ON THE EASTERN SIDES OF THE MOUNTAINS. WITH
HEIGHTS FALLING A BIT, THE MARINE LAYER WILL BEGIN TO DEEPEN,
MAKING IT FURTHER INLAND EACH NIGHT AFTER WEDNESDAY. WEAK RIDGING
BUILDS BACK IN THIS WEEKEND, AND TEMPERATURES LOOK TO BEGIN TO
WARM BY SUNDAY.
AVIATION
260400Z...COAST/VALLEYS...LOW CLOUDS RETURNING TO COASTAL KSAN
AROUND 06Z, KCRQ AROUND 08Z AND AT KSNA AFTER 10Z. EXPECT BASES
AROUND 1200 FT MSL LOWERING TO AROUND 800 FT MSL 10Z-16Z. LOW CLOUDS
AND FOG LIKELY TO EXTEND UP TO 15 MILES INLAND BY SUNRISE. CLEARING
TO THE BEACHES EXPECTED 16Z-17Z.
MOUNTAINS/DESERTS...+SHRA/TSRA EXPECTED AGAIN TUESDAY AFTERNOON WITH
CB BASES AROUND 10 KFT. 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 WEDNESDAY.
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...SS/ZUBER
AVIATION/MARINE...PG
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