756
FXUS66 KSGX 180943
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
243 AM PDT WED JUN 18 2025
SYNOPSIS
HIGH PRESSURE ALOFT WILL CONTINUE HIGH TEMPERATURES AS MUCH AS 8
TO 12 DEGREES ABOVE AVERAGE TODAY FOR THE MOUNTAINS, DESERTS, AND
INLAND VALLEYS. FOR THURSDAY THROUGH THE WEEKEND, THERE WILL BE A
COOLING TREND WITH WEEKEND HIGH TEMPERATURES AS MUCH AS 5 TO 10
DEGREES BELOW AVERAGE FOR THE MOUNTAINS DURING THE WEEKEND. THE
MARINE LAYER WILL DEEPEN WITH NIGHT AND MORNING COASTAL LOW CLOUDS
SPREADING FARTHER INTO THE VALLEYS. THERE MAY BE WARMING OF
AROUND 5 DEGREES FOR EARLY NEXT WEEK BUT WITH HIGH TEMPERATURES
REMAINING BELOW AVERAGE.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHORT TERM (TODAY THROUGH FRIDAY)
THE MARINE LAYER IS AROUND 1400 FEET DEEP WITH NOT MUCH CHANGE IN
DEPTH OVER THE PAST 24 HOURS. A WEAK COASTAL EDDY SHOULD HELP TO
MAINTAIN THAT DEPTH TODAY, EVEN AS HIGH PRESSURE ALOFT TO THE
SOUTH STRENGTHENS SLIGHTLY. LOW CLOUDS ALONG THE COAST WILL SPREAD
INTO PORTIONS OF INLAND ORANGE COUNTY EARLY THIS MORNING TO
AROUND INTERSTATE 5 IN NORTHERN ORANGE COUNTY, AND IN SAN DIEGO
COUNTY INTO THE FAR WESTERN VALLEYS.
HIGH TEMPERATURES FOR THE MOUNTAINS WILL WARM AROUND 5 DEGREES
TODAY WITH SLIGHT COOLING FOR THE WESTERN VALLEYS AND INLAND
COASTAL AREAS. HIGH TEMPERATURES FOR TODAY WILL BE AS MUCH AS 8 TO
12 DEGREES ABOVE AVERAGE FOR THE MOUNTAINS, DESERTS, AND INLAND
VALLEYS RANGING FROM THE LOWER 70S NEAR THE COAST TO THE 90S TO
AROUND 100 FOR THE INLAND EMPIRE WITH 112 TO 116 FOR THE LOWER
DESERTS.
FOR THURSDAY INTO THE WEEKEND, A LOW PRESSURE SYSTEM OVER THE
EASTERN PACIFIC WILL MOVE SLOWLY INTO THE WESTERN STATES. THIS
WILL STRENGTHEN THE ONSHORE FLOW ACROSS SOUTHERN CALIFORNIA AND
WEAK HIGH PRESSURE ALOFT. THIS WILL SPREAD COOLING INLAND WITH
COOLING ON THURSDAY OF A FEW DEGREES TO AROUND 5 DEGREES FOR THE
MOUNTAINS AND INLAND VALLEYS WITH SLIGHTLY GREATER ADDITIONAL
COOLING ON FRIDAY.
WITH THE COOLING, FRIDAY HIGH TEMPERATURES WILL BE AROUND 5
DEGREES BELOW AVERAGE FOR THE MOUNTAINS, BUT STILL AROUND 5
DEGREES ABOVE AVERAGE FOR THE LOWER DESERTS. HIGH TEMPERATURES ON
FRIDAY WILL RANGE FROM AROUND 70 NEAR THE COAST TO THE 80S TO
AROUND 90 FOR THE INLAND EMPIRE WITH 105 TO 110 FOR THE LOWER
DESERTS.
THE MARINE LAYER WILL BEGIN TO DEEPEN, TO 1500 TO 2000 FEET FOR
FRIDAY WITH NIGHT AND MORNING COASTAL LOW CLOUDS SPREADING INTO
PORTIONS OF THE WESTERN VALLEYS.
LONG TERM (SATURDAY THROUGH TUESDAY)
THE COOLING WILL CONTINUE INTO THE WEEKEND WITH WEEKEND HIGH
TEMPERATURES A FEW DEGREES BELOW AVERAGE NEAR THE COAST TO 5 TO 10
DEGREES BELOW AVERAGE FOR THE MOUNTAINS AND VALLEYS WITH HIGH
TEMPERATURES RANGING FROM AROUND 70 NEAR THE COAST TO THE UPPER
70S TO UPPER 80S FOR THE INLAND EMPIRE WITH THE UPPER 90S TO
AROUND 100 FOR THE LOWER DESERTS. THE MARINE LAYER WILL DEEPEN TO
2000 TO 2500 FEET WITH NIGHT AND MORNING COASTAL LOW CLOUDS
SPREADING FARTHER INTO THE VALLEYS.
FOR MONDAY AND TUESDAY, HIGH TEMPERATURES MAY WARM AROUND 5
DEGREES, BUT REMAIN BELOW AVERAGE WITH NIGHT AND MORNING COASTAL
LOW CLOUDS SPREADING INTO PORTIONS OF THE VALLEYS.
AVIATION
180930Z....COAST/WESTERN VALLEYS...LOW CLOUDS BASED 600-1000 FT MSL
WITH RELATIVELY PATCHY COVERAGE HAVE DEVELOPED FROM CENTRAL ORANGE
COUNTY THROUGH SAN DIEGO WITH ABOUT 10 MILES OF INLAND EXTENT AT
TIMES. BEST CONFIDENCE IN CIGS MAINTAINING AT KSAN BUT MAY SCATTER
OUT OCCASIONALLY AT KCRQ. KSNA LOOKS TO STAY CIG FREE BUT COULD SEE
INSTANCES OF BKN CIGS AT TIMES. VIS RESTRICTIONS TO 4-6 SM IN BR
ALONG THE COASTS, BUT LOCALLY 1-4SM ON COASTAL MESAS OR HIGHER
TERRAIN. CLOUDS CLEAR BACK OUT BY 15-16Z THIS MORNING, WITH MOSTLY
CLEAR SKIES PREVAILING THROUGH THE AFTERNOON. CLOUDS WITH MORE
UNIFORM COVERAGE REDEVELOP AND MOVE INLAND AFTER 03Z THU, WITH
SLIGHTLY HIGHER BASES 700-1100 FT MSL AND GREATER INLAND EXTENT TO
10-15 MILES FROM THE COAST.
INLAND VALLEYS/MOUNTAINS/DESERTS...CLEAR SKIES AND UNRESTRICTED
VIS THROUGH THURSDAY MORNING.
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...HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR ORANGE COUNTY
INLAND AREAS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO AND
RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO COUNTY
MOUNTAINS-SAN DIEGO COUNTY VALLEYS-SANTA ANA MOUNTAINS AND
FOOTHILLS.
PZ...NONE.
PUBLIC...17
AVIATION/MARINE...MUNYAN
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