976
FXUS66 KSGX 201607
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
907 AM PDT TUE MAY 20 2025
SYNOPSIS
CONDITIONS WILL CONTINUE TO WARM THROUGH WEDNESDAY FOR AREAS WEST OF
THE MOUNTAINS AND THROUGH THURSDAY FOR THE DESERTS. THE MARINE LAYER
WILL REMAIN SHALLOW AND PATCHY, ONLY IMPACTING LOCATIONS ALONG THE
COAST THROUGH THURSDAY. BRIEF COOLING TREND EXPECTED FRIDAY/SATURDAY
WITH A DEEPER MARINE LAYER AND A SLIGHT UPTICK IN WESTERLY WINDS
OVER THE MOUNTAINS AND DESERTS. FOR EARLY NEXT WEEK, MINOR DAILY
TEMPERATURE FLUCTUATIONS EXPECTED WITH A MORE PERSISTENT MARINE
LAYER FOR THE COAST AND PORTIONS OF THE VALLEYS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
HIGH TEMPERATURES TODAY ARE EXPECTED TO BE 5 TO 10 DEGREES WARMER
THAN YESTERDAY FOR MOST LOCATIONS. MARINE LAYER LOW CLOUDS AND FOG
IMPACTED PORTIONS OF THE COAST OVERNIGHT, WITH VISIBLE SATELLITE
AT 9 AM SHOWING LINGERING LOW CLOUDS IN SOUTHERN SAN DIEGO COUNTY.
PATCHY LOW CLOUDS AND FOG WILL CONTINUE FOR TONIGHT INTO
WEDNESDAY MORNING ALONG THE IMMEDIATE COAST. FOG MAY BE LOCALLY
DENSE AT TIMES. CONDITIONS ON WEDNESDAY WILL BE A FEW DEGREES
WARMER THAN TODAY, WITH AREAS OF MODERATE HEATRISK EXPECTED IN THE
INLAND VALLEYS AND LOW DESERTS. BASED ON THE CURRENT FORECAST,
THE INLAND EMPIRE AND THE LOW DESERTS HAVE THE MOST WIDESPREAD
COVERAGE OF MODERATE HEATRISK. HIGH TEMPERATURES IN THE INLAND
EMPIRE ARE EXPECTED TO REACH THE MID TO UPPER 90S ON WEDNESDAY,
WITH HIGHS IN THE LOW DESERT EXPECTED TO BE NEAR 105 DEGREES.
CHANCES OF THE INLAND EMPIRE EXCEEDING 100 DEGREES ON WEDNESDAY IS
LOCALLY 15 TO 20 PERCENT IN THE WARMEST LOCATIONS, ELSEWHERE
CHANCES ARE LESS THAN 10 PERCENT.
HIGHS ON THURSDAY WILL BE A FEW DEGREES COOLER THAN WEDNESDAY WEST
OF THE MOUNTAINS, WITH A COUPLE ADDITIONAL DEGREES OF WARMING IN THE
LOW DESERT. CHANCES OF TEMPERATURES IN THE LOW DESERT EXCEEDING 110
DEGREES ARE SLIM TO NONE FOR WEDNESDAY AND THURSDAY. BY FRIDAY, ALL
AREAS WILL BE UP TO 5 DEGREES COOLER THAN THURSDAY AS A LOW
PRESSURE SYSTEM MOVES ACROSS THE PACIFIC NORTHWEST. THERE IS A
LESS THAN 5 PERCENT CHANCE OF HIGH TEMPERATURES REACHING OR
EXCEEDING 105 DEGREES IN THE LOW DESERT ON FRIDAY. WEST OF THE
MOUNTAINS THE INLAND EMPIRE LOCALLY HAS A 20 TO 30 PERCENT CHANCE
OF EXCEEDING 90 DEGREES FRIDAY WITH THOSE CHANCES CONFINED TO THE
TYPICALLY HOTTEST LOCATIONS, ELSEWHERE CHANCES ARE LESS THAN 10
PERCENT. IN ADDITION TO COOLER CONDITIONS, THE AFTERNOON SEA
BREEZE WINDS WILL BE ENHANCED ON THE DESERT MOUNTAIN SLOPES INTO
THE DESERTS.
ADDITIONAL COOLING IS EXPECTED ON SATURDAY WITH HIGH TEMPERATURES
WITHIN A FEW DEGREES OF AVERAGE. SATURDAY HIGH TEMPERATURES WILL
RANGE FROM THE MID TO UPPER 60S NEAR THE COAST TO THE UPPER 70S TO
MID 80S FOR THE INLAND EMPIRE WITH THE MID 90S TO AROUND 100 FOR
THE LOWER DESERTS. THE MARINE LAYER WILL DEEPEN TO AROUND 2500
FEET FOR THE WEEKEND. NIGHT AND MORNING COASTAL LOW CLOUDS WILL
SPREAD INLAND INTO PORTIONS OF THE INLAND VALLEYS WITH SLOWER OR
MORE LIMITED AFTERNOON CLEARING NEAR THE COAST. SUNDAY MAY WARM
SLIGHTLY FOLLOWED BY MINOR DAY TO DAY DIFFERENCES THROUGH THE
MIDDLE OF NEXT WEEK. NIGHT AND MORNING COASTAL LOW CLOUDS WILL
CONTINUE TO SPREAD INTO PORTIONS OF THE VALLEYS EACH NIGHT.
AVIATION
201530Z...COAST...MOSTLY CLEAR SKIES TODAY INTO WEDNESDAY. EXCEPT
FOR PATCHY LOW CLOUDS AND FOG TO REDEVELOP AFTER 08Z, WITH ANY CIGS
200-400 FEET MSL AND VIS 0-5SM, MOST LIKELY NEAR KSAN AND BETWEEN 10-
15Z WEDNESDAY.
ELSEWHERE...CLEAR WITH UNRESTRICTED VIS THROUGH TUESDAY.
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...CO
AVIATION/MARINE...MM
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