173
FXUS66 KSGX 271628
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
928 AM PDT THU MAR 27 2025
SYNOPSIS
COOL WITH A DEEP MARINE AND PATCHY DRIZZLE AT TIMES THROUGH THE
WEEKEND. THERE WILL BE GUSTY WEST WINDS FOR THIS AFTERNOON
THROUGH FRIDAY NIGHT WITH THE STRONGER GUSTS FOR THE MOUNTAINS
AND DESERTS MOSTLY 40 TO 50 MPH. COOLER THAN AVERAGE CONDITIONS
WILL CONTINUE INTO NEXT WEEK WITH CHANCES FOR PRECIPITATION
INCREASING TO AROUND 50 PERCENT FOR NEXT WEDNESDAY AND THURSDAY.
CONFIDENCE IS LOWER WITH THE TIMING AND POTENTIAL AMOUNTS. DAILY
CHANCES FOR ONE INCH OR MORE OF RAINFALL ARE 25 PERCENT OR LESS
FOR THE TYPICALLY WETTER LOCATIONS ON THE COASTAL SLOPES OF THE
MOUNTAINS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
MORNING UPDATE
ONSHORE WINDS WILL CONTINUE TODAY, WITH INCREASING WINDS ACROSS
THE MOUNTAINS AND DESERTS, NOTABLY THIS EVENING AND OVERNIGHT.
HREF PROBABILITIES ARE MODERATE TO HIGH IN SEEING WIND GUSTS OVER
45 MPH ACROSS E-W PASSES IN THE SD/RIV COUNTY MOUNTAIN AREAS.
SOME HIGH CLOUDS PASSING THROUGH ASSOCIATED WITH AN UPPER LEVEL
LOW ACROSS THE PACIFIC NORTHWEST, WHILE LOW CLOUDS HAVE FILLED THE
COASTAL BASIN. THE MARINE LAYER IS NEARLY 4,000 FEET DEEP, WHICH
WILL MAKE IT FOR ANOTHER TIME OF SLOWER MIXING AND CLEARING. SOME
SUBSIDENCE OVER THE OCEAN IS HELPING TO PARTIALLY CLEAR OUT SOME
COASTAL AREAS LATER THIS MORNING. THE DEEP MARINE LAYER WILL
CONTINUE OVER THE NEXT COUPLE OF MORNINGS WITH PATCHY DRIZZLE
EXPECTED WEST OF THE MOUNTAINS.
PREVIOUS DISCUSSION
SHORT TERM (TODAY THROUGH SATURDAY)
THE NAM CHANCES FOR MEASURABLE PRECIPITATION FOR THE COAST INTO
THE VALLEYS ARE GREATER AGAIN FOR LATE TONIGHT INTO FRIDAY MORNING
AND AGAIN FOR LATE FRIDAY NIGHT INTO SATURDAY MORNING WITH
DRIZZLE IN THE FORECAST FOR PORTIONS OF THE COAST, VALLEYS, AND
COASTAL WATERS FOR THOSE TIMES.
LITTLE CHANGE IS EXPECTED WITH HIGH TEMPERATURES FOR THE COAST AND
VALLEYS THROUGH THE WEEKEND WITH COOLING FOR THE DESERTS FOR TODAY
AND FRIDAY FOLLOWED BY LITTLE CHANGE FOR THE WEEKEND. THERE WILL
BE STRONGER ONSHORE FLOW THROUGH FRIDAY NIGHT WITH AREAS OF
STRONGER AND GUSTY WEST WINDS FOR THIS AFTERNOON THROUGH FRIDAY.
THE STRONGER WINDS ARE EXPECTED IN THE MOUNTAINS AND DESERTS WITH
THE STRONGER GUSTS ALONG AND BELOW THE DESERT SLOPES OF THE
MOUNTAINS TO 40 TO 50 MPH.
LONG TERM (SUNDAY THROUGH WEDNESDAY)
NOT MUCH CHANGE FOR SUNDAY. THERE MAY BE SLIGHT WARMING ON MONDAY
AND SLIGHT COOLING ON TUESDAY. PRECIPITATION FROM A LOW PRESSURE
SYSTEM CENTERED OFF THE PACIFIC NORTHWEST COAST WILL MOSTLY REMAIN
NORTH OF THE AREA FOR MONDAY AND TUESDAY WITH NBM DAILY CHANCES
FOR MEASURABLE PRECIPITATION LESS THAN 20 PERCENT.
FOR WEDNESDAY THROUGH SATURDAY OF NEXT WEEK, THERE REMAIN GREATER
DIFFERENCES AMONG MODEL ENSEMBLE MEMBERS IN THE TIMING AND
LOCATION OF LOW PRESSURE SYSTEMS MOVING ACROSS THE EASTERN PACIFIC
INTO THE WESTERN STATES WITH LOWER CONFIDENCE IN THE DETAILS OF
THE FORECAST FOR SOUTHWESTERN CALIFORNIA FOR NEXT WEDNESDAY AND
THURSDAY. THE DETERMINISTIC NBM FOR HIGH TEMPERATURES SHOWS SLIGHT
COOLING ON WEDNESDAY WITH A FEW MORE DEGREES OF COOLING FOR
THURSDAY, THOUGH WITH GREATER SPREAD IN THE GUIDANCE FOR BOTH
DAYS.
NBM DAILY CHANCES FOR MEASURABLE PRECIPITATION INCREASE TO 40 TO
50 PERCENT FOR WEDNESDAY AND 50 TO 60 PERCENT THURSDAY OF NEXT
WEEK, BUT WITH DAILY CHANCES FOR ONE INCH OR MORE OF RAINFALL 25
PERCENT OR LESS ON THE TYPICALLY WETTER LOCATIONS ON THE COASTAL
SLOPES OF THE MOUNTAINS.
AVIATION
271630Z...COAST/VALLEYS/FOOTHILLS...LOW CLOUDS CONTINUE TO PERSIST
ACROSS THE COASTAL BASIN THIS MORNING WITH BASES LARGELY BETWEEN
3000-3500FT MSL, TOPPED TO ~4000FT. VIS REDUCTIONS LIMITED TO THE
FOOTHILLS WHERE CLOUDS INTERSECT HIGHER TERRAIN. PARTIAL SCATTERING
EXPECTED AROUND 18-19Z, ESPECIALLY FOR COASTAL AREAS AND THE
FOOTHILLS. LOW CLOUDS FILL BACK IN ACROSS THE COASTAL BASIN AFTER
00Z THIS EVENING, BECOMING WIDESPREAD AFTER 02-04Z. BASES THIS
EVENING AND TONIGHT WILL LIKELY BE LOWER THAN THIS MORNING, WITH A
85% CHANCE OF BASES BELOW 3000FT MSL. THERE IS A 20% CHANCE OF CIGS
LESS THAN 2000FT THROUGH 12Z THIS EVENING, WITH BASES LIKELY LIFTING
AFTER 12Z.
HIGHER MOUNTAINS/DESERTS...SCT HIGH CLOUDS ABOVE 20000 FEET MSL.
WESTERLY WINDS OVER THE RIDGES STRENGTHEN AND SPREAD THROUGH THE LEE
SLOPES INTO DESERTS AFTER 19Z, WITH GUSTS 30-50 KTS. WINDS PERSIST
THROUGH SATURDAY. AREAS OF MODERATE UP/DOWNDRAFTS IN LEE OF
MOUNTAINS.
MARINE
NORTHWESTERLY WINDS PICK UP THIS AFTERNOON AND CONTINUE TO INCREASE
OVERNIGHT. BY EARLY FRIDAY, 15-20 KT WINDS WITH GUSTS TO 25 KTS ARE
EXPECTED TO PERSIST THROUGH SATURDAY MORNING. WINDS REMAIN ELEVATED
SATURDAY AFTERNOON BEFORE WEAKENING LATE SATURDAY INTO SUNDAY.
SEAS INCREASE EARLY FRIDAY TO 6-11 FEET IN THE OUTER COASTAL WATERS
WITH SHORT PERIODS OF 7-9 SECONDS, DIMINISHING THROUGHOUT THE DAY
SATURDAY. SMALL CRAFT ADVISORY IS IN EFFECT AND CONTAINS MORE
DETAILS. CHOPPY SEAS AND HAZARDOUS BOATING CONDITIONS ARE LIKELY.
OTHERWISE, NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED BEFORE AND
AFTER THAT PERIOD.
BEACHES
ELEVATED SURF 4-6 FEET, WITH LOCAL SETS TO 8 FEET ON WEST-FACING
BEACHES, AND HIGH RIP CURRENT RISK EXPECTED FRIDAY AND SATURDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 AM FRIDAY TO 5 AM PDT SATURDAY FOR
WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING
10 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND.
UPDATE...APR
PUBLIC...17
AVIATION/MARINE...MUNYAN
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