257
FXUS66 KSGX 082344
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
444 PM PDT SAT AUG 8 2026
SYNOPSIS
MINOR TO MAJOR HEATRISK CONTINUES FOR MUCH OF THE REGION THROUGH
SUNDAY BEFORE COOLER WEATHER RETURNS TUESDAY AND BEYOND.
THUNDERSTORM CHANCES EACH DAY IN THE MOUNTAINS SUNDAY THROUGH
WEDNESDAY, WITH BEST CHANCES AND HIGHEST RAIN RATES MONDAY AND
TUESDAY. PATCHY COASTAL FOG THROUGH SUNDAY MORNING WITH A DEEPER
MARINE LAYER AFTER MONDAY.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
..UPDATED AVIATION/MARINE/BEACHES DISCUSSION
MID LEVEL WATER VAPOR IMAGERY SHOWS HIGH PRESSURE FIRMLY IN PLACE
OVER THE FOUR CORNERS, WITH ONGOING HEAT IMPACTS FOR SOUTHERN
CALIFORNIA. HIGHS BOTH TODAY AND TOMORROW WILL BE AROUND 3-7 DEGREES
ABOVE NORMAL WITH WARM OVERNIGHT LOWS 4-10 DEGREES ABOVE NORMAL,
RESULTING IN MINOR TO MODERATE HEATRISK FOR INLAND AND VALLEY AREAS
AND MODERATE TO MAJOR HEATRISK FOR THE DESERTS. A HEAT ADVISORY
AND EXTREME HEAT WARNING REMAIN IN EFFECT THROUGH SUNDAY EVENING.
OUTSIDE OF THE HEAT, ATTENTION RETURNS TO MONSOONAL MOISTURE AS THE
UPPER LEVEL RIDGE WILL ELONGATE AND STRETCH THIS COMING WEEK,
ALLOWING FOR MULTIPLE WEAK WAVES TO MOVE ACROSS. FORCING THIS
AFTERNOON LOOKS LIMITED WITH LACKLUSTER LOW-LEVEL MOISTURE FOR AREAS
OTHER THAN THE SOUTHERN MOUNTAINS. IF ANY STORMS MANAGE TO DEVELOP,
THEY WILL LIKELY BE CONFINED TO THE HIGHER TERRAIN THIS AFTERNOON
WITH LIMITED IMPACTS. THE RIDGE WILL BECOME A BIT MORE COMPRESSED
TONIGHT AND, AS SEEN FRIDAY MORNING, ANOTHER VERY WEAK EASTERLY WAVE
MAY BE ABLE TO MOVE ACROSS BAJA LATE TONIGHT. LOCALIZED LIGHT
RAINFALL WILL POSSIBLE IN SAN DIEGO COUNTY SUNDAY MORNING,
ALTHOUGH THE BEST CHANCES FOR ANY EARLY MORNING PRECIPITATION WILL
BE IN THE SAN DIEGO COUNTY MOUNTAINS AND FOOTHILLS, OR EASTERN
I-8 CORRIDOR. THIS WINDOW WILL ALSO ALLOW FOR LOW AND MID LEVEL
MOISTURE TO BEGIN TO SURGE FURTHER NORTHWARD, REACHING RIVERSIDE
AND SAN BERNARDINO COUNTIES BY EARLY SUNDAY AFTERNOON AS PW VALUES
RETURN ABOVE 1.15. WHILE NOT SENSATIONAL, THIS, ALONG WITH THE
SLIGHT BREAKDOWN IN THE RIDGE, MAY ALLOW FOR A FEW DECENT
THUNDERSTORMS TO DEVELOP OVER THE MOUNTAINS, ESPECIALLY IN
RIVERSIDE AND SAN DIEGO COUNTIES, SUNDAY AFTERNOON (30-40%
CHANCE). BRIEF, HEAVY RAINFALL WITH RAIN RATES UP TO
0.50-0.75"/HR AND LIGHTNING WILL BE THE MAIN THREATS. THERE WILL
BE AROUND A 10-20% CHANCE FOR A STORM TO FIRE OFF OF THE SAN
BERNARDINO MOUNTAINS AROUND THIS TIME TOO, BUT RAIN RATES THAT FAR
NORTH WILL LIKELY BE 0.40"/HR OR LESS. IF YOU ARE SPENDING TIME
IN THE MOUNTAINS THIS WEEKEND, ENSURE YOU ARE PREPARED TO TAKE
SHELTER IN A STURDY, ENCLOSED STRUCTURE SHOULD YOU FIND YOURSELF
CAUGHT IN A THUNDERSTORM. TREES ARE NOT A SAFE PLACE TO SHELTER
FROM LIGHTNING!
THE PATTERN SHIFTS COOLER BEGINNING MONDAY AS HIGH PRESSURE SLIDES
EAST, WITH A DEEPENING MARINE LAYER INTO THE END OF THE WEEK. THE
POSITION OF THE HIGH CENTERED OVER THE SOUTH PLAINS AND A SEPARATE
HIGH OFF THE COAST WILL ESTABLISH UPPER LEVEL TROUGHING FOR MUCH
OF CA AS WE COOL BACK DOWN TO NEAR NORMAL FOR MID AUGUST BY
TUESDAY. MONDAY AND TUESDAY WILL ONCE AGAIN FEATURE AFTERNOON
MONSOONAL CONVECTION IN THE MOUNTAINS AS MOISTURE IS PULLED
NORTHWARD AND PWS REACH ~1.5. BOTH OF THESE DAYS COULD SEE MORE
WIDESPREAD STORMS AND HIGHER RAIN RATES, WITH A SLIGHTLY HIGHER
POTENTIAL FOR STORMS TO MOVE OFF THE MOUNTAINS AND INTO THE
DESERTS COMPARED TO SUNDAY. AFTERNOON STORMS OVER THE MOUNTAINS
WILL BE POSSIBLE EACH DAY THROUGH THE END OF NEXT WEEK, BUT
CHANCES DECREASE AFTER TUESDAY AS A MORE ROBUST TROUGH TAKES
EFFECT.
YOU'VE BEEN PATIENT, AND THE COOLER WEATHER IS FINALLY IN VIEW!
AVIATION
082230Z....COAST...PATCHY LOW CLOUDS WITH BASES 800-1200 FT MSL WILL
DEVELOP GRADUALLY OVERNIGHT, WITH CIGS MOST LIKELY BETWEEN 11-15Z
SUNDAY. ANY CIGS SHOULD SCATTER OUT SUNDAY BY 15-16Z.
VALLEYS/MOUNTAINS/DESERTS...SCT CUMULUS WITH BASES AT 10000 FT MSL
OVER MTNS THROUGH 01Z SUN. MORE WIDESPREAD CUMULUS DEVELOPMENT OVER
MTNS 19Z SUN-03Z MON WITH 20-35% CHANCE OF TSRA IN THE MTNS. HIGH
CLOUDS MAY DRIFT INTO THE VALLEYS AND DESERTS WITH BASES AOA 10000
FT MSL SUN AFTERNOON AND EVENING.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH THURSDAY.
BEACHES
ASTRONOMICAL HIGH TIDES ARE EXPECTED TO EXCEED 7 FT MONDAY THROUGH
WEDNESDAY BETWEEN 8-9:30 PM PDT. SURF IS NOT EXPECTED TO PLAY A
LARGE ROLE IN ELEVATING THE TIDES FURTHER, WITH A SURF FORECAST OF
ONLY 2-3 FT. REGARDLESS, TIDES EXCEEDING 7 FT CAN RESULT IN MINOR
TIDAL OVERFLOW INTO LOW-LYING AREAS ALONG THE BEACH, INCLUDING BEACH
PARKING LOTS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...HEAT ADVISORY UNTIL 8 PM PDT SUNDAY 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 SUNDAY FOR APPLE AND LUCERNE
VALLEYS-COACHELLA VALLEY-SAN DIEGO COUNTY DESERTS-SAN
GORGONIO PASS NEAR BANNING.
PZ...NONE.
PUBLIC...ZUBER
AVIATION/MARINE/BEACHES...CO
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