007
FXUS66 KSGX 222021
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
121 PM PDT TUE SEP 22 2026
SYNOPSIS
WARMER CONDITIONS FOR THE MIDDLE TO END OF THE WEEK WITH ABOVE
AVERAGE TEMPERATURES. THE MARINE LAYER IS EXPECTED TO GET SHALLOWER
WITH NIGHT AND MORNING LOW CLOUDS AND FOG NOT REACHING AS FAR
INLAND. THERE IS A A SLIGHT CHANCE OF SHOWERS AND ISOLATED
THUNDERSTORMS OVER THE MOUNTAINS THURSDAY AFTERNOON, WITH OTHERWISE
DRY CONDITIONS EXPECTED TO PREVAIL. COOLER CONDITIONS MAY RETURN FOR
EARLY NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SUNNIER SKIES ARE EXPECTED THIS AFTERNOON WITH HIGH TEMPERATURES
RUNNING NEAR TO UP TO 7 DEGREES WARMER THAN YESTERDAY. THE MARINE
LAYER IS EXPECTED TO GET SHALLOWER OVER THE NEXT FEW NIGHTS, STAYING
MOSTLY CONFINED THE THE COAST. CONDITIONS WILL WARM THROUGH THE
MIDDLE OF THE WEEK.
WEDNESDAY, HIGH TEMPERATURES WILL WARM 5 TO 12 DEGREES FOR THE
VALLEYS, WITH 3 TO 5 DEGREES OF WARMING ELSEWHERE. ADDITIONAL
WARMING IS EXPECTED THROUGH SATURDAY WITH TEMPERATURES ALONG THE
COAST WITH THE HIGHEST DEPARTURE FROM NORMAL AT 7 TO 12 DEGREES. FOR
THE LATTER HALF OF THE WEEK, OVERNIGHT LOWS WILL INCREASE TO THE MID-
60S TO 70 WEST OF THE MOUNTAINS AND IN THE UPPER 70S TO LOW 80S IN
THE LOW DESERT. MODERATE HEATRISK IS EXPECTED ALONG THE COAST FRIDAY
AND SATURDAY AND IN THE LOW DESERTS FOR THE SECOND HALF OF THE WEEK.
MODERATE HEATRISK HAS THE MOST IMPACTS ON THOSE SENSITIVE TO HEAT,
ESPECIALLY THOSE WITHOUT COOLING/HYDRATION. A LOW PRESSURE SYSTEM
IS EXPECTED TO MOVE INLAND EARLY NEXT WEEK WHICH WILL BRING
COOLING CONDITIONS AND A DEEPER MARINE LAYER.
FOR THURSDAY, A CLOSED LOW LINGERING TO OUR SOUTHWEST WILL START TO
MOVE EAST. THIS WILL DRAW MOISTURE INTO SOUTHERN CALIFORNIA FROM
THE SOUTHEAST INCREASING CHANCES FOR PRECIPITATION, MAINLY IN THE
MOUNTAINS. THERE REMAINS A 10% CHANCE OF THUNDERSTORMS OVER THE
MOUNTAINS.
TROPICAL CYCLONE POLO, CURRENTLY OFF THE SOUTHWEST COAST OF
MEXICO, IS NOW A MAJOR HURRICANE. POLO IS BASICALLY STATIONARY BUT
IS EXPECTED TO MOVE GENERALLY WEST-NORTHWEST OVER THE NEXT FEW
DAYS. THERE REMAINS A LOT OF UNCERTAINTY IN THE FORECAST FOR LATE
IN THE WEEKEND INTO NEXT WEEK BUT THERE COULD EVENTUALLY BE AT
LEAST SOME PERIPHERAL IMPACTS TO PORTIONS OF SOUTHERN CALIFORNIA.
RIGHT NOW, IT LOOKS LIKE THE MOST LIKELY IMPACTS WILL BE COASTAL
FLOODING AND EROSION BUT THAT WILL ULTIMATELY DEPEND ON THE TRACK,
INTENSITY, AND DURATION OF THE CYCLONE.
AVIATION
221800Z...COAST/VALLEYS...NEARLY ALL LOW CLOUDS HAVE CLEARED OUT
THIS MORNING, WITH VFR CONDITIONS EXPECTED TO PREVAIL INTO THE
AFTERNOON. CLOUDS WITH LOWER BASES (INITIALLY AROUND 2000-2500FT
MSL) LOOK TO REDEVELOP ACROSS COASTAL SAN DIEGO COUNTY AFTER 00Z
WEDNESDAY. HIGH CONFIDENCE IN CIGS AT KSAN, LOWER CONFIDENCE AT KCRQ
BETWEEN 00-06Z. AFTER 06Z, CIGS LOOK TO SPREAD THROUGHOUT COASTAL SD
COUNTY AND NORTHWARD TOWARDS ORANGE COUNTY, WITH BASES LIKELY
LOWERING TO AROUND 1500FT MSL. MODERATE CONFIDENCE IN CIGS AT KSNA
BETWEEN 11-16Z. CLOUDS SCATTER OUT BETWEEN 16-17Z WEDNESDAY.
OTHERWISE...MOSTLY CLEAR SKIES 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...MUNYAN
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