771
FXUS66 KSGX 161900
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
1200 PM PDT WED SEP 16 2026
SYNOPSIS
BELOW AVERAGE TEMPERATURES WILL CONTINUE THROUGH FRIDAY. CONDITIONS
WILL WARM OVER THE WEEKEND, WITH A BRIEF COOLING TREND EARLY IN
THE WEEK. CONDITIONS WILL WARM FOR THE MIDDLE OF NEXT WEEK,
RETURNING TO AROUND AVERAGE BY NEXT WEDNESDAY. NIGHT AND MORNING
LOW CLOUDS AND FOG WILL REACH WELL INTO THE VALLEY AGAIN TONIGHT
INTO THURSDAY, BECOMING SHALLOWER OVER THE WEEKEND.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
THE MARINE LAYER WAS AROUND 3500 FT DEEP THIS MORNING, WITH LOW
CLOUDS FILLING IN THE COASTAL BASIN. VISIBLE SATELLITE FROM THIS
MORNING EVEN SHOWED LOW CLOUDS THROUGH THE CAJON PASS. AT 11 AM,
SATELLITE WAS STILL SHOWING PATCHY LOW CLOUDS ALONG THE COAST AND
PORTIONS OF THE WESTERN VALLEYS. THE MARINE LAYER IS EXPECTED TO
STAY A SIMILAR DEPTH TONIGHT, WITH SIMILAR INLAND EXTENT EXPECTED.
THE MARINE LAYER WILL BECOME SHALLOWER FOR FRIDAY INTO THE WEEKEND
WITH NIGHT AND MORNING COASTAL LOW CLOUDS NOT SPREADING INLAND PAST
THE FAR WESTERN VALLEYS.
WEAK TROUGHING WILL GRADUALLY MOVE EAST INTO THE GREAT BASIN BY THIS
WEEKEND. THAT WILL RESULT IN BELOW COOLER CONDITIONS THROUGH
THURSDAY, WITH A GRADUAL WARMING FRIDAY THROUGH SUNDAY AS WEAK
TRANSIENT RIDGING BUILDS OVER THE WEST COAST. THE WARMING WILL BE
MOST NOTICEABLE FOR INLAND LOCATIONS. EVEN WITH THE WARMING
DAYTIME HIGHS, OVERNIGHT LOWS WILL CONTINUE TO COOL OFF HELPING
OVERNIGHT RELIEF FROM THE HEAT.
ANOTHER TROUGH OF LOW PRESSURE IS EXPECTED TO MOVE WEST ACROSS
SOUTHERN CALIFORNIA MONDAY WHICH WILL BRING A FEW DEGREES OF COOLING
AND DEEPEN THE MARINE LAYER AGAIN. BY THE MIDDLE OF NEXT WEEK, THERE
STARTS TO BE SOME SPREAD IN THE UPPER LEVEL PATTERN. NBM GUIDANCE
HAS AN 8 DEGREE DIFFERENCE BETWEEN THE 75TH (WARMER END OF
SOLUTIONS) AND 25TH (COOLER END OF SOLUTIONS) PERCENTILE
TEMPERATURES FOR THE INLAND VALLEYS. THE CURRENT FORECAST FOLLOWS
THE NBM WHICH HAS TEMPERATURES WITHIN A FEW DEGREES OF AVERAGE FOR
MOST LOCATIONS.
AVIATION
161745Z...COAST/VALLEYS...SCT-BKN CLOUDS 3000-4500 FT MSL WILL
CONTINUE TO SCATTER OUT OF COASTAL/W VALLEY AREAS THROUGH ABOUT 20Z
THIS MORNING. LOW CLOUDS AROUND 2500-3000 FEET MSL WILL MOVE ASHORE
AFTER 02Z AND AGAIN FILL MOST OF THE COASTAL BASIN OVERNIGHT INTO
THURSDAY MORNING. THESE WILL AGAIN GENERALLY RISE ABOVE 3000 FT MSL
TOWARDS 16-17Z, THEN SCATTER OUT 17-20Z THU.
MOUNTAINS/DESERTS...MOSTLY CLEAR AND VFR CONDITIONS TODAY AND
TONIGHT.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH SUNDAY.
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...CO
AVIATION/MARINE...CSP
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