981
FXUS66 KSGX 221037
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
337 AM PDT TUE APR 22 2025
SYNOPSIS
THERE WILL BE A GRADUAL COOLING TREND INTO SATURDAY WITH SATURDAY
HIGH TEMPERATURES A FEW DEGREES BELOW AVERAGE NEAR THE COAST TO
10 TO 15 DEGREES BELOW AVERAGE FOR THE MOUNTAINS. THE MARINE LAYER
WILL DEEPEN INTO SATURDAY WITH NIGHT AND MORNING COASTAL LOW
CLOUDS EXTENDING WELL INLAND AND ONTO THE COASTAL MOUNTAIN SLOPES
BY WEDNESDAY. INCREASED SEA BREEZE WINDS ARE EXPECTED EACH
AFTERNOON AND EVENING FOR THE MOUNTAINS AND DESERTS. IT WILL BE
DRY WITH A WARMING TREND FOR SUNDAY THROUGH TUESDAY WITH TUESDAY
HIGH TEMPERATURES WARMING TO AROUND AVERAGE. THE MARINE LAYER WILL
BECOME SHALLOWER WITH NIGHT AND MORNING COASTAL LOW CLOUDS NOT
EXTENDING AS FAR INLAND.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHORT TERM (TODAY THROUGH THURSDAY)
A WEAK LOW PRESSURE SYSTEM MOVING INLAND ALONG THE WEST COAST FOR
TONIGHT AND WEDNESDAY FOLLOWED BY A SECOND STRONGER LOW PRESSURE
SYSTEM THAT WILL BE APPROACHING THE WEST COAST ON THURSDAY WILL
BRING A GRADUAL COOLING TREND FOR TODAY THROUGH SATURDAY.
HIGH TEMPERATURES TODAY WILL BE AROUND 4 TO 8 DEGREES ABOVE
AVERAGE FOR THE DESERTS INTO THE MOUNTAINS WITH HIGH TEMPERATURES
FOR THE COAST AND VALLEYS AS MUCH AS 5 DEGREES BELOW AVERAGE FOR
THE WESTERN VALLEYS IN SAN DIEGO COUNTY AND INLAND ORANGE COUNTY.
WITH THE CONTINUED COOLING, HIGH TEMPERATURES ON THURSDAY WILL
FALL TO AROUND AVERAGE FOR THE DESERTS WITH THE WESTERN VALLEYS
AND INLAND ORANGE COUNTY AROUND 4 TO 8 DEGREES BELOW AVERAGE.
THE MARINE LAYER HAS DEEPENED TO AROUND 2500 FEET WITH SATELLITE
IMAGERY SHOWING WIDESPREAD LOW CLOUDS OVER THE COASTAL WATERS
EXTENDING INLAND ACROSS MUCH OF THE SAN DIEGO COUNTY VALLEYS AND
AS OF 3 AM BEGINNING TO SPREAD INTO FAR SOUTHERN AND FAR WESTERN
PORTIONS OF THE INLAND EMPIRE. THE MARINE LAYER IS EXPECTED TO
CONTINUE DEEPENING INTO SATURDAY WITH COASTAL LOW CLOUDS COVERING
MUCH OF THE VALLEYS FOR EARLY WEDNESDAY AND SPREADING ONTO THE
COASTAL MOUNTAIN SLOPES FOR EARLY THURSDAY.
LONG TERM (FRIDAY THROUGH TUESDAY)
THE COOLING TREND WILL CONTINUE THROUGH SATURDAY AS A LOW PRESSURE
SYSTEM MOVES INLAND THROUGH CALIFORNIA FRIDAY NIGHT AND SATURDAY.
THE MARINE LAYER WILL CONTINUE TO DEEPEN WITH COASTAL LOW CLOUDS
EXTENDING WELL INLAND AND ONTO THE COASTAL SLOPES OF THE
MOUNTAINS. WITH THE COOLING, SATURDAY HIGH TEMPERATURES
WOULD BE A FEW DEGREES BELOW AVERAGE NEAR THE COAST TO 10 TO 15
DEGREES BELOW AVERAGE FOR THE MOUNTAINS.
NBM HAS THE CHANCE OF MEASURABLE PRECIPIATION ON SATURDAY AT LESS
THAN 10 PERCENT. HOWEVER, GFS AND ECMWF MOS AND NBM DEVELOPMENTAL
VERSION 5.0 BOTH HAVE CHANCES FOR MEASURABLE PRECIPITATION MORE
CONSISTENT WITH THE PATTERN, AROUND 15 PERCENT NEAR THE COAST TO
20 TO 30 PERCENT IN THE MOUNTAINS. MOST LIKELY ANY PRECIPITATION
WOULD BE LIGHT.
DRY WITH A WARMING TREND FOR SUNDAY THROUGH TUESDAY WITH TUESDAY
HIGH TEMPERATURES WARMING TO AROUND AVERAGE. THE MARINE LAYER WILL
BECOME SHALLOWER WITH COASTAL LOW CLOUDS NOT EXTENDING AS FAR
INLAND.
AVIATION
220930Z....COASTS/VALLEYS...LOW CLOUDS BASED 1100-1600 FT MSL WITH
TOPS TO 2000 FT MSL HAVE FILLED IN ACROSS THE COAST BASIN, SPREADING
INTO THE INLAND VALLEYS AND PORTIONS OF THE INLAND EMPIRE. 70%
CHANCE OF CIGS REACHING KONT (AND 30% CHANCE AT KSBD) BETWEEN 11-16Z.
VIS REDUCTIONS TO 1-5 SM WITHIN INLAND VALLEYS AND ON HIGHER COASTAL
TERRAIN. CLOUDS SCATTER OUT FROM EAST TO WEST 16-19Z LATER THIS
MORNING. LOW CLOUDS AT 1500-2000FT MSL LOOK TO REFORM AND PUSH
INLAND AGAIN AFTER 02Z WEDNESDAY TO AGAIN COVER MUCH OF THE COASTAL
BASIN AND MOST OF THE INLAND VALLEYS.
OTHERWISE...MOSTLY CLEAR TONIGHT THROUGH TUESDAY MORNING, WITH
FEW-SCT HIGH CLOUDS TUESDAY AFTERNOON AND EVENING.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH SATURDAY.
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...17
AVIATION/MARINE...MUNYAN
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