496
FXUS66 KSGX 071058
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
358 AM PDT FRI AUG 7 2026
SYNOPSIS
THROUGH SUNDAY, MODERATE HEATRISK IS EXPECTED IN THE MOUNTAINS
AND INLAND EMPIRE WITH MAJOR HEATRISK IN THE DESERTS. THERE ARE
CHANCES OF SHOWERS AND ISOLATED THUNDERSTORMS IN THE MOUNTAINS
EACH AFTERNOON THROUGH TUESDAY. GRADUALLY COOLER AND DRIER FOR THE
LATTER HALF OF NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHORT TERM (TODAY THROUGH SUNDAY)
THUNDERSTORMS DEVELOPED LATE THURSDAY EVENING ON THE LEADING EDGE
OF A MESOSCALE CONVECTIVE VORTEX THAT HAS BEEN MOVE WESTWARD ALONG
BORDER BETWEEN SOUTHERN CALIFORNIA AND NORTHERN BAJA INTO AN
ATMOSPHERE THAT THE LATE THURSDAY AFTERNOON NKX SOUNDING SHOWED
HAD A MOST UNSTABLE CAPE OF 1649 J/KG AND AN LI OF -6. THE 06Z
RRFS SHOWS THE CENTER OF THE MCV TURNING TOWARD THE NORTHWEST AND
TRACKING ALONG THE VICINITY OF THE SOUTHERN CALIFORNIA COAST FROM
NORTHWESTERN SAN DIEGO COUNTY INTO SOUTHERN LOS ANGELES COUNTY
THIS MORNING. SO FAR, THERE'S NO INDICATION THAT THERE IS
SUFFICIENT INSTABILITY IN THAT AREA FOR NEW THUNDERSTORM DEVELOPMENT
TO OCCUR THIS MORNING.
THE THUNDERSTORMS THAT HAVE BEEN MOVING TOWARD THE WEST ACROSS
SOUTHERN SAN DIEGO COUNTY OVERNIGHT SHOULD CROSS THE COAST AROUND
4 AM AND CONTINUE TO WEAKEN. GAGES ACROSS SOUTHERN SAN DIEGO
COUNTY HAVE SHOWN RAINFALL OF 0.25 TO 0.50 INCH. THROUGH 3 AM,
THERE HAD BEEN 86 CLOUD-TO-GROUND LIGHTNING STRIKES ACROSS SAN
DIEGO COUNTY SINCE LATE THURSDAY EVENING WITH 499 LIGHTNING
FLASHES OF ALL TYPES (CLOUD-TO-GROUND, IN-CLOUD, CLOUD-TO-CLOUD,
ETC.). CHANCES FOR AFTERNOON SHOWERS AND THUNDERSTORMS FOR THE
MOUNTAINS AND DESERTS WILL DECREASE FOR TODAY AND SATURDAY, VERSUS
THE COVERAGE ON THURSDAY AFTERNOON. CHANCES FOR AFTERNOON SHOWERS
AND THUNDERSTORMS FOR THE MOUNTAINS AND DESERTS WILL INCREASE
AGAIN TO 15 TO 20 PERCENT ON SUNDAY.
THE HEATRISK IS EXPECTED TO PEAK ON SATURDAY WITH WIDESPREAD
MAJOR HEATRISK FOR THE DESERTS AND MODERATE HEATRISK FOR THE
MOUNTAINS AND INLAND EMPIRE WITH ONLY A SLIGHT DECREASE FOR
SUNDAY.
LONG TERM (MONDAY THROUGH THURSDAY)
THE SLIGHT CHANCE FOR AFTERNOON SHOWERS AND THUNDERSTORMS FOR THE
MOUNTAINS AND DESERTS WILL CONTINUE THROUGH WEDNESDAY FOLLOWED BY
SLOW COOLING AND DRYING THROUGH THE FOLLOWING WEEKEND. A GREATER
DECREASE IN HEATRISK IS STILL EXPECTED FOR MONDAY AND TUESDAY. IT
IS UNLIKELY THE EXTREME HEAT WARNING FOR THE DESERTS AND HEAT
ADVISORY FOR THE MOUNTAINS AND INLAND EMPIRE WILL BE EXTENDED
BEYOND SUNDAY.
AVIATION
071030Z....COASTS...VERY PATCHY LOW CLOUDS BASED 1000-1400 FT MSL
WILL STRUGGLE TO INCREASE IN COVERAGE THIS MORNING. GREATEST CHANCE
(30-40%) FOR CIGS AT COASTAL TAF SITES WILL BE 12-15Z FRI. ANY LOW
CLOUDS SHOULD CLEAR TO THE COASTLINE BY 16Z. VFR CONDITIONS EXPECTED
FRIDAY AFTERNOON AND EVENING. LOW CLOUDS RETURN LATE FRIDAY NIGHT
WITH SIMILAR BASES AND PATCHY COVERAGE.
VALLEYS/MOUNTAINS/DESERTS...SCT TO LOCALLY BKN CLOUDS AOA 10000
FEET MSL THROUGH FRIDAY AFTERNOON.
OTHERWISE, A CLUSTER OF SHOWERS AND STORMS HAS A HISTORY OF
PRODUCING LIGHTNING OVER THE FAR SOUTHERN SAN DIEGO COUNTY. AS
THIS ACTIVITY CONTINUES TO MOVE TOWARD THE WEST, THERE IS A SLIGHT
CHANCE FOR LIGHTNING TO AFFECT OTHER NEARBY AIRPORTS (20% AT
KNRS, 10% AT KSAN). ANY STORM ACTIVITY SHOULD DIMINISH BY 6 AM PDT.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH TUESDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...HEAT ADVISORY UNTIL 8 PM PDT SUNDAY FOR RIVERSIDE COUNTY
MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN BERNARDINO
AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO
COUNTY MOUNTAINS.
EXTREME HEAT WARNING UNTIL 8 PM PDT SUNDAY FOR APPLE AND LUCERNE
VALLEYS-COACHELLA VALLEY-SAN DIEGO COUNTY DESERTS-SAN
GORGONIO PASS NEAR BANNING.
PZ...NONE.
PUBLIC...17
AVIATION/MARINE...KW
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