995
FXUS66 KSGX 092340
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
440 PM PDT SUN AUG 9 2026
SYNOPSIS
MINOR TO MODERATE HEATRISK CONTINUES THROUGH MONDAY WITH COOLER
WEATHER TUESDAY AND BEYOND. THUNDERSTORM CHANCES EACH DAY IN THE
MOUNTAINS THROUGH WEDNESDAY, WITH BEST CHANCES AND HIGHEST RAIN
RATES MONDAY AND TUESDAY. PATCHY COASTAL FOG MONDAY MORNING WITH A
DEEPENING MARINE LAYER THROUGH THE END OF THE WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
..UPDATED AVIATION DISCUSSION
SATELLITE SHOWS HIGH CLOUDS STREAMING INTO RIVERSIDE AND SAN
BERNARDINO COUNTIES FROM THE SOUTHEAST AFTER A COLLAPSED MCS THIS
MORNING, ALTHOUGH ANY PRECIPITATION DIED OFF BEFORE REACHING OUR
BORDERS. MUCH OF THE HIGH CLOUDS SHOULD MOVE OUT BY THE AFTERNOON,
AND HIGH PRESSURE SITUATED OVER THE FOUR CORNERS WILL KEEP
TEMPERATURES WELL ABOVE NORMAL AND ALLOW FOR MONSOONAL THUNDERSTORMS
TO DEVELOP OVER THE HIGHER TERRAIN THIS AFTERNOON. PW VALUES ABOVE
1" INDICATE THAT BRIEF, HEAVY RAINFALL WILL BE POSSIBLE WITH ANY
STORM, BUT REALISTIC MAXIMUM RAIN RATES ARE LIKELY CLOSER TO
0.60"/HR OR LESS FOR RIVERSIDE AND SAN DIEGO MOUNTAINS AND 0.40"/HR
OR LESS FOR SAN BERNARDINO THIS AFTERNOON.
SOUNDINGS ARE A BIT MORE OPTIMISTIC FOR STORM POTENTIAL ON
MONDAY/TUESDAY AS THE HIGH BECOMES MORE COMPRESSED BY UPPER LEVEL
TROUGHING OVER THE PACNW, ALLOWING FOR A MORE UNSTABLE ENVIRONMENT
AND MONSOONAL MOISTURE TO SURGE UP INTO THE MOUNTAINS OF SOCAL.
TEMPERATURES WILL ALSO BEGIN TO COOL ON MONDAY AS WE SHED THE LAST
OF OUR HEAT PRODUCTS. WHILE HEATRISK WILL BE LOWER ON MONDAY, HIGHS
WILL STILL BE ABOVE 100 IN THE HIGH DESERTS AND ABOVE 105 IN THE LOW
DESERTS, SO CONTINUE BEST PRACTICES WHEN SPENDING TIME OUTDOORS -
FREQUENT WATER/AC BREAKS AND AVOID STRENUOUS ACTIVITY DURING THE
HOTTEST PARTS OF THE DAY. IF ATTEMPTING TO ESCAPE TO THE MOUNTAINS
TO AVOID THE HEAT, BE PREPARED FOR MORE WIDESPREAD THUNDERSTORMS
MONDAY AFTERNOON WITH HEAVY RAIN, FREQUENT LIGHTNING, AND LOCALIZED
FLOODING POSSIBLE AS INSTABILITY PEAKS ON THIS DAY. WITH EASTERLY
FLOW AND AMPLE MID AND LOW LEVEL MOISTURE, PWS WILL BE INCREASING
CLOSER TO 1.5-1.6, AND RAIN RATES MAY POTENTIALLY EXCEED 1-1.25"/HR
AT TIMES WITH ANY ANCHORED STORM. THE MAJORITY OF THE STORMS ARE
EXPECTED TO REMAIN IN THE MOUNTAINS, BUT A FEW STRONGER CELLS MAY
MAKE IT OFF AND MIGRATE INTO THE DESERTS.
TEMPERATURES WILL COOL FURTHER TUESDAY BACK DOWN TO NEAR NORMAL AS
HEIGHTS CONTINUE TO FALL AND THE MARINE LAYER DEEPENS INTO THE END
OF THE WEEK. ONE FINAL DAY OF SCATTERED MONSOONAL THUNDERSTORMS IN
THE HIGHER TERRAIN AS PWS REMAIN AT OR ABOVE 1.5" AND INSTABILITY
LINGERS ACROSS SOUTHEASTERN CA. AFTER TUESDAY, MORE ROBUST UPPER
LEVEL TROUGHING AND THE HIGH SLIDING FURTHER EASTWARD WILL USHER IN
SLIGHTLY BELOW NORMAL TEMPERATURES INTO THE END OF THE WEEK, ALONG
WITH LOWER STORM CHANCES (10-15% CHANCE FOR A STORM OR TWO OFF THE
HIGHER TERRAIN WILL EXIST EACH AFTERNOON WED-FRI). THIS COOLER
WEATHER WILL BE A WELCOME CHANGE AFTER TEMPERATURES HAVE REMAINED
AT OR ABOVE NORMAL SINCE EARLY JULY.
AVIATION
092330Z....COAST...PATCHY LOW CLOUDS TO GRADUALLY DEVELOP OVERNIGHT,
INCREASING IN COVERAGE AND DURATION, WITH BEST CHANCES OF CIGS
BETWEEN 11-15Z TUESDAY. BASES AROUND 700-1000 FEET MSL. SCATTER OUT
OF ANY CIGS TUESDAY BY 16Z.
VALLEYS/MOUNTAINS/DESERTS...ISOLD TSRA MAINLY OVER MOUNTAINS AND
HIGH DESERT THROUGH 03Z. BASES AROUND 10000 FEET MSL WITH TOPS TO
40000 FEET. OTHERWISE SCT-BKN DEBRIS CLOUDS MOSTLY ABOVE 15000 FEET
THROUGH 18Z MONDAY. SCATTERED TSRA AFTER 18Z MONDAY WITH BASES
AROUND 9000 FEET MSL WITH TOPS TO 50000 FEET. ANY TSRA COULD PRODUCE
LIGHTNING, STRONG UP/DOWNDRAFTS AND ASSOCIATED VIS REDUCTIONS.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH FRIDAY.
BEACHES
HIGH TIDES WILL EXCEED 7 FEET DURING EVENINGS MONDAY THROUGH
WEDNESDAY BETWEEN 800-930 PM, RESULTING IN MINOR TIDAL OVERFLOW OF
LOW-LYING AREAS ALONG THE BEACH. SURF WILL BE LOW AND IS NOT
EXPECTED TO ADD MUCH TO THE FLOODING POTENTIAL. CHECK THE COASTAL
FLOOD ADVISORY FOR DETAILS.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...COASTAL FLOOD ADVISORY FROM 6 PM MONDAY TO 11 PM PDT WEDNESDAY
FOR ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL
AREAS.
HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR ORANGE COUNTY
INLAND AREAS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO
COUNTY MOUNTAINS-SAN BERNARDINO AND RIVERSIDE COUNTY
VALLEYS-THE INLAND EMPIRE-SAN DIEGO COUNTY MOUNTAINS-SAN
DIEGO COUNTY VALLEYS-SANTA ANA MOUNTAINS AND FOOTHILLS.
EXTREME HEAT WARNING UNTIL 8 PM PDT THIS EVENING FOR APPLE AND
LUCERNE VALLEYS-COACHELLA VALLEY-SAN DIEGO COUNTY DESERTS-
SAN GORGONIO PASS NEAR BANNING.
PZ...NONE.
PUBLIC...ZUBER
AVIATION/MARINE/BEACHES...MM
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