801
FXUS66 KSGX 171040
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
240 AM PST MON FEB 17 2025
SYNOPSIS
COOLING WILL SPREAD INLAND TODAY AND TUESDAY AS THE MARINE LAYER
RETURNS AND DEEPENS FOR TONIGHT INTO TUESDAY MORNING. THERE WILL
BE PATCHY LOW CLOUDS AND LOCALLY DENSE FOG NEAR THE COAST EARLY
THIS MORNING WITH MORE WIDESPREAD COASTAL LOW CLOUDS SPREADING
INTO PORTIONS OF THE INLAND VALLEYS FOR LATE TONIGHT INTO TUESDAY
MORNING. THERE WILL BE GUSTY WEST WINDS FOR THE MOUNTAINS AND
DESERTS FOR TODAY AND TONIGHT WITH THE STRONGEST GUSTS ALONG THE
DESERT SLOPES OF THE MOUNTAINS TO 40 TO 50 MPH. SLIGHTLY WARMER ON
WEDNESDAY, SLIGHTLY COOLER ON THURSDAY, THEN A WARMING TREND
THROUGH NEXT WEEKEND WITH SUNDAY HIGH TEMPERATURES AS MUCH AS 10
TO 15 DEGREES ABOVE AVERAGE FOR THE MOUNTAINS AND INLAND VALLEYS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHORT TERM (TODAY THROUGH WEDNESDAY)
A LOW PRESSURE SYSTEM MOVING INLAND THROUGH THE PACIFIC NORTHWEST
AND NORTHERN CALIFORNIA WILL STRENGTHEN ONSHORE FLOW ACROSS
SOUTHERN CALIFORNIA THROUGH TONIGHT. A WEAK COASTAL EDDY WILL BRING
A RETURN OF PATCHY LOW CLOUDS AND LOCALLY DENSE FOG NEAR THE
COAST EARLY THIS MORNING.
THE COASTAL EDDY WILL BRING MORE RAPID DEEPENING OF THE MARINE
FOR TONIGHT INTO TUESDAY MORNING WITH MORE WIDESPREAD COASTAL LOW
CLOUDS SPREADING INTO PORTIONS OF THE INLAND VALLEYS FOR LATE
TONIGHT INTO TUESDAY MORNING. FOR TUESDAY NIGHT INTO WEDNESDAY
MORNING, THE MARINE LAYER WILL BEGIN TO DECREASE IN DEPTH AND THE
COVERAGE OF LOW CLOUDS WILL BECOME PATCHIER, MAINLY COVERING
PORTIONS OF THE SAN DIEGO COUNTY COASTAL WATERS, SAN DIEGO COUNTY
COASTAL AREAS, AND PORTIONS OF THE SAN DIEGO COUNTY VALLEYS.
THE STRONGER ONSHORE FLOW WILL BRING GUSTY WEST WINDS TO THE
MOUNTAINS AND DESERTS FOR TODAY INTO TONIGHT WITH GUSTS TO 30 TO
40 MPH. ALONG THE EAST SLOPES OF THE MOUNTAINS AND IN THE
NORTHERN COACHELLA VALLEY BELOW THE SAN GORGONIO PASS, THERE WILL
BE LOCALLY STRONGER GUSTS TO 40 TO 50 MPH.
THE STRONGER ONSHORE FLOW WILL ALSO SPREAD COOLING INLAND FOR
TODAY AND TUESDAY WITH HIGH TEMPERATURES TODAY FOR THE COAST AND
VALLEYS A FEW TO AROUND 5 DEGREES COOLER THAN SUNDAY WITH ANOTHER
FEW TO AROUND 5 DEGREES OF COOLING FOR MANY AREAS ON TUESDAY. THEN
A FEW TO AROUND 5 DEGREES OF WARMING ON WEDNESDAY WITH WEAKER
ONSHORE FLOW AND A DECREASE IN THE DEPTH OF THE MARINE LAYER.
LONG TERM (THURSDAY THROUGH SUNDAY)
A LOW PRESSURE SYSTEM MOVING INLAND ALONG THE WEST COAST ON
WEDNESDAY NIGHT AND THURSDAY WILL BRING BRIEFLY STRONGER ONSHORE
FLOW TO SOUTHERN CALIFORNIA WITH HIGH TEMPERATURES A FEW DEGREES
COOLER ON THURSDAY. THEN WARMER AND DRY FOR FRIDAY THROUGH THE
WEEKEND AS HIGH PRESSURE ALOFT STRENGTHENS ACROSS CALIFORNIA. WITH
THE WARMING, HIGH TEMPERATURES ON SUNDAY WILL BE AS MUCH AS 10 TO
15 DEGREES ABOVE AVERAGE FOR THE MOUNTAINS AND INLAND VALLEYS,
INTO THE UPPER 60S NEAR THE COAST TO THE MID 70S TO LOWER 80S IN
THE VALLEYS AND IN THE LOWER TO MID 80S FOR THE LOWER DESERTS.
AVIATION
171030Z...COAST/VALLEYS...PATCHY AND INTERMITTENT LOW CLOUDS AND FOG
EXPECTED THROUGH 16Z, WITH LOW CONFIDENCE ON ANY LONG LASTING IFR
CIGS/VIS AT COASTAL AIRPORTS. BASES WILL BE AROUND 200-600 FEET MSL
WITH VIS 1-5SM IN BR. LOW CLOUDS TO DEVELOP HIGHER BUT EARLIER THIS
EVENING AFTER 02Z, PUSHING INLAND OVERNIGHT. BASES INITIALLY WOULD
BE AROUND 1000-1500 FEET MSL, RISING OVERNIGHT INTO TUESDAY. SOME
VIS REDUCTIONS OVER HIGHER COASTAL TERRAIN. OTHERWISE, SCT-BKN HIGH
CLOUDS TODAY AND TONIGHT.
MOUNTAINS/DESERTS...WESTERLY WINDS AFTER 21Z THROUGH TONIGHT, WITH
SURFACE GUSTS 25-45 KTS, STRONGEST OVER THE RIDGES, DESERT SLOPES,
AND THE HIGH DESERT. MODERATE UP/DOWNDRAFTS POSSIBLE IN LEE OF
RIDGES. PATCHY BLDU REDUCING VIS IN THE DESERT. SCT-BKN HIGH CLOUDS
TODAY AND TONIGHT.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE ANTICIPATED THROUGH FRIDAY.
BEACHES
A LONG-PERIOD SWELL WILL ARRIVE TUESDAY, GENERATING LARGE SURF UP TO
6-7 FEET, A HIGH RIP CURRENT RISK, AND SOME DANGEROUS SWIMMING
CONDITIONS. SWELL AND SURF WILL EASE SOMEWHAT WEDNESDAY.
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/BEACHES...MM
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