731
FXUS66 KSGX 180345
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
845 PM PDT SAT MAY 17 2025
SYNOPSIS
COOL AND CLOUDY WITH CHANCES OF LIGHT RAIN AND DRIZZLE WEST OF
THE MOUNTAINS INTO TOMORROW MORNING, THEN DRYING WILL OCCUR FROM
TOMORROW AFTERNOON AND ONWARD. AS THE TROUGH MOVES EAST, A RIDGE
DEVELOPS INTO NEXT WEEK, QUICKLY WARMING TEMPERATURES AND
RENDERING A SHALLOWER MARINE LAYER. PERIODS OF LOCALLY GUSTY
OFFSHORE WINDS ARE EXPECTED MONDAY MORNING THROUGH MONDAY
AFTERNOON.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
UPDATE: RADAR ECHOES REVEAL THAT THERE ARE SOME VERY LIGHT RAIN
SHOWERS AND/OR DRIZZLE CURRENTLY MOVING OVER PORTIONS OF THE COASTAL
AND INLAND VALLEYS. THIS WILL LIKELY CONTINUE THROUGH MOST OF THE
OVERNIGHT HOURS BUT THEN BEGIN TO TAPER OFF COMPLETELY GOING INTO
THE EARLY MORNING HOURS. ANY LIGHT RAIN, AND/OR DRIZZLE THAT IS ABLE
TO ACCUMULATE IS NOT EXPECTED TO EXCEED MORE THAN A TENTH OF AN
INCH. A CONSENSUS OF THE LATEST HIGH RES GUIDANCE HAS THE MAJORITY
OF PRECIP ENDING BY AROUND NOON TOMORROW. FROM THERE, IT WILL LIKELY
CONTINUE TO CLEAR OUT BY THE AFTERNOON FOR MOST LOCATIONS AND
TEMPERATURES TOMORROW WILL BE SLIGHTLY WARMER FROM WHERE THEY WERE
TODAY, ESPECIALLY WITHIN THE IE.
MONDAY STILL SHOWS AN OFF-SHORE FLOW RETURNING, WHICH WILL HELP TO
LEAD TO FURTHER DRYING AND WARMING, WITH NOTABLY MILDER
TEMPERATURES, EVEN FOR THE COASTAL AREAS WHICH ARE NOT IMPEDED BY
THE MARINE LAYER. THIS TREND WILL CONTINUE TO DRASTICALLY WARM GOING
INTO TUESDAY AND WEDNESDAY AS THE RIDGE BEGINS TO BUILD BACK IN AND
STRENGTHENS OVER THE REGION. BECAUSE OF THIS, THERE WILL POSSIBLY BE
THE NEED OF HEAT ADVISORIES FOR PORTIONS OF THE INLAND VALLEYS AND
LOWER DESERTS ON WEDNESDAY THROUGH THURSDAY. OTHERWISE, THERE WILL
CONTINUE TO BE TRANQUIL CONDITIONS GOING INTO THE LATER PART OF THE
WEEK, WITH A SLIGHT COOLDOWN BY THE TIME WE HEAD INTO THE FOLLOWING
WEEKEND.
(PREVIOUS DISCUSSION SUBMITTED AT 150 PM):
THIS AFTERNOON...AN UPPER LEVEL TROUGH FROM THE GULF OF ALASKA WILL
CONTINUE TO DIG THROUGH THE GREAT BASIN THIS AFTERNOON, REACHING ITS
MAXIMUM SOUTHERN EXTENT BY TONIGHT AROUND THE CALIFORNIA/ARIZONA
BORDER, PUSHING SLOWLY EASTWARD THROUGHOUT SUNDAY, THEN BREAKING
DOWN MONDAY AS THE UPPER LEVEL FLOW BECOMES MORE ZONAL. WIND GUSTS
OF 35-45 MPH ARE BEING OBSERVED IN THE HIGH DESERTS. STRONGEST WINDS
WILL BE OBSERVED THIS EVENING THROUGHOUT SOUTHERN CALIFORNIA WITH
GUSTS OF 45-55 MPH IN THE MOUNTAINS AND DESERTS AND LOCALLY UP TO 65
MPH IN THE WINDIEST LOCATIONS. AREAS OF BLOWING DUST ARE POSSIBLE IN
THE DESERTS, REDUCING VISIBILITY AT TIMES.
TONIGHT, THE MARINE LAYER WILL BECOME THICK ENOUGH TO RING OUT
INTERMITTENT LIGHT RAIN THROUGH EARLY SUNDAY MORNING, ESPECIALLY FOR
SAN DIEGO COUNTY AREAS BELOW 5000 FEET. TOTAL RAINFALL SHOULD AMOUNT
TO NO MORE THAN 0.10 INCHES.
DRY WITH A WARMING TREND BEGINNING ON SUNDAY AS LOW PRESSURE MOVES
EASTWARD INTO THE ROCKIES AND WEAK HIGH PRESSURE BUILDS OVER THE
WEST COAST. A SURFACE HIGH MOVING INTO THE GREAT BASIN WILL BRING
PERIODS OF WEAK OFFSHORE FLOW ON MONDAY, WITH LOCALLY GUSTY
NORTHEAST TO EAST WINDS. CURRENT GUIDANCE SHOWS THE OFFSHORE WINDS
PEAKING LATE MONDAY MORNING WITH LOCAL WIND GUSTS OF 35 TO 40 MPH ON
THE COASTAL SLOPES OF THE SAN BERNARDINO MTNS, IN THE NORTHERN PARTS
OF THE IE AND IN THE SANTA ANA MTNS. THE OFFSHORE WINDS WILL WEAKEN
ON MONDAY EVENING. WEAK OFFSHORE WINDS WILL ALSO BE OBSERVED TUESDAY
MORNING.
UNDER HIGH PRESSURE ALOFT, TEMPERATURES WILL CONTINUE TO RISE
THROUGH MIDWEEK AND WED AND THU ARE LIKELY TO BE THE WARMEST DAYS
WITH DAYTIME HIGH TEMPS REACHING THE MID TO UPPER 90S IN THE IE ON
BOTH THOSE DAYS. 45-55% CHANCE OF EXCEEDING 100F IN THE IE WED AND
THU. THE MARINE LAYER WILL MAINTAIN LESS OF A PRESENCE WITH DAY-TO-
DAY VARIATIONS ON THE AMOUNT OF LOW CLOUDS/FOG DURING THE NIGHTS AND
MORNINGS BUT DAYTIME TEMPERATURES WILL REACH THE MID 70S NEAR THE
COAST.
TEMPERATURES WILL AGAIN TREND LOWER FOR NEXT WEEKEND AS A LOW
PRESSURE TROUGH APPROACHES FROM THE NORTHWEST BUT THERE ISN'T MUCH
CONFIDENCE IN THE DETAILS OF THE FORECAST DUE TO THE SPREAD AMONG
MODEL SOLUTIONS.
AVIATION
180310Z...COAST/VALLEYS...MULTIPLE SCT-OVC CLOUD LAYERS WITH BASES
BETWEEN 1500-3500 FT MSL AND TOPS TO 5500 FT MSL CONTINUING
OVERNIGHT. ISO-SCT SHRA CONTINUING THROUGH ABOUT 18Z SUNDAY, WHICH
MAY PRODUCE OCCASIONAL VIS DOWN TO 3-6 SM. CLOUDS BECOMING SCT TO
LOCALLY BKN AFTER 17Z SUNDAY WITH BASES 2500-3500 FT MSL, MOSTLY
CLEARING OUT BY THE EVENING. THERE IS A 60% CHANCE OF CIGS
REDEVELOPING SUNDAY NIGHT INTO MONDAY MORNING ALONG THE COAST AND UP
TO 20-25 MI INLAND WITH BASES AROUND 1500-2000 FT MSL.
MOUNTAINS/DESERTS...WEST WINDS WITH GUSTS GUSTS 35-55KTS OVER THE
DESERT MOUNTAIN SLOPES/FOOTHILLS AND THROUGH PASSES THROUGH ABOUT
08Z. STRONG UP/DOWNDRAFTS AND ROTORS OVER AND EAST OF THE MOUNTAINS
THROUGH, INCLUDING AT KPSP AND VIS LOCALLY REDUCED TO 4-6 SM IN BLDU
WITH THESE WINDS. WINDS WILL GRADUALLY WEAKEN INTO SUNDAY MORNING,
WIDESPREAD GUSTS 25-35KTS AGAIN AFTER 23Z SUNDAY, WEAKENING SUNDAY
NIGHT.
MARINE
WEST-NORTHWEST WINDS GUSTING TO 20 KT NEAR SAN CLEMENTE ISLAND INTO
EARLY SUNDAY WILL CREATE LOCALLY ROUGH SEAS IN THE FAR OUTER COASTAL
WATERS. OTHERWISE, NO HAZARDOUS MARINE CONDITIONS EXPECTED THROUGH
THURSDAY.
BEACHES
ELEVATED SURF WILL IMPACT BEACHES SUNDAY AND EARLY MONDAY, PEAKING
SUNDAY AFTERNOON/EVENING. EXPECTED SURF OF 3-5 FEET WITH SETS TO 6
FEET PRODUCING A HIGH RIP CURRENT RISK.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...WIND ADVISORY UNTIL 2 AM PDT SUNDAY FOR APPLE AND LUCERNE
VALLEYS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY
MOUNTAINS-SAN DIEGO COUNTY DESERTS-SAN DIEGO COUNTY
MOUNTAINS-SAN GORGONIO PASS NEAR BANNING.
PZ...NONE.
UPDATE...STEWEY
PUBLIC...WESTERINK
AVIATION/MARINE/BEACHES...SS
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