603
FXUS66 KLOX 251138
AFDLOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
438 AM PDT FRI APR 25 2025
SYNOPSIS
24/707 PM.
A DEEP MARINE LAYER AND STRONG ONSHORE FLOW WILL MAINTAIN A COOL
WEATHER PATTERN THROUGH FRIDAY. IT WILL BE MOSTLY CLOUDY WITH
PATCHY DRIZZLE EACH MORNING, THEN SKIES WILL PARTIALLY CLEAR EACH
AFTERNOON. AN UPPER LOW AND FRONTAL SYSTEM WILL LIKELY BRING SOME
RAIN TO THE AREA ON SATURDAY. AFTER THE UPPER LOW MOVES EAST OF
THE REGION, DRY WEATHER IS EXPECTED SUNDAY THROUGH MIDWEEK, WITH A
WARMING TREND.
SHORT TERM (TDY-SUN)
25/437 AM.
CLOUDS HAVE PUSHED INTO JUST ABOUT ALL OF THE FORECAST AREA THIS
MORNING, WITH THE EXCEPTION OF THE MOUNTAINS ABOUT 5000 OR 5500
FEET, AND THE ANTELOPE VALLEY. HOWEVER, THANKS TO A WEAKENING
INVERSION, THE MARINE LAYER WAS ON THE VERGE OF TRANSITIONING TO
JUST A VERY DEEP MOIST THIS MORNING. A FEW LOCATIONS IN THE
FOOTHILLS OF L.A. COUNTY HAVE REPORTED VERY LIGHT AMOUNTS OF RAIN
DURING THE PAST FEW HOURS, BUT THOSE REPORTS WITH RATHER
ISOLATED. STILL, THERE COULD BE SOME PATCHY LIGHT DRIZZLE OR
VERY LIGHT MEASURABLE RAIN THROUGH THE MORNING, ESPECIALLY IN THE
FOOTHILLS SOUTH OF PT. CONCEPTION.
GRADIENTS REMAINED STRONGLY ONSHORE, ABOUT 7 MB ONSHORE FROM KLAX
TO KDAG, WHICH IS ABOUT THE SAME AS THEY WERE THU MORNING AT THIS
TIME. STRONG ONSHORE GRADIENTS WILL LIKELY PRODUCE GUSTY SOUTHWEST
TO WEST WINDS LATER THIS MORNING THROUGH THIS EVENING IN THE MTNS
OF L.A. AND VTU COUNTIES, THROUGH THE HIGHWAY 14 CORRIDOR, AND
INTO THE ANTELOPE VALLEY AND ADJACENT FOOTHILLS. WINDS ARE
EXPECTED TO STAY JUST BELOW ADVISORY LEVELS, THOUGH THERE WILL
LIKELY BE SOME ISOLATED GUSTS TO 50 MPH IN SOME OF THE WINDIEST
LOCATIONS. MODELS SHOW SKIES BECOMING PARTLY CLOUDY IN MOST AREAS
THIS AFTERNOON, BUT WITH A DEEP MOIST LAYER AND STRONG ONSHORE
FLOW, CLEARING COULD BE SLOW. SINCE THE MOIST LAYER IS SO DEEP, IT
MAY BE A DAY OF REVERSE CLEARING, WHERE COASTAL AREAS CLEAR
BETTER AND FASTER THAN THE VALLEYS. IT WILL BE A CHILLY DAY, WITH
HIGHS IN THE MID 50S TO MID 60S WEST OF THE MOUNTAINS, A GOOD 10
TO 15 DEGREES BELOW NORMAL.
AN UPPER LOW LOCATED ABOUT 350 NM W OF EUREKA EARLY THIS MORNING
WILL DROP SLOWLY SOUTHWARD TODAY, REACHING A POSITION ABOUT 400
NM W OF PT. CONCEPTION LATE THIS AFTERNOON. IT WILL THEN TRACK
EASTWARD, REACHING THE WEST COAST OF SBA OR SOUTHERN SAN LUIS
OBISPO COUNTY LATE SAT MORNING, THEN LIFT EAST-NORTHEASTWARD INTO
THE SOUTHERN SAN JOAQUIN VALLEY LATE SAT AFTERNOON.
CLOUDS WILL INCREASE ACROSS THE REGION TONIGHT. MODELS SHOW AN
ORGANIZES FRONTAL SYSTEM WITH SURFACE FEATURE ASSOCIATED WITH THE
UPPER LOW. RAIN WILL BECOME LIKELY ACROSS SLO AND SBA COUNTIES
LATE TONIGHT, WITH A CHANCE OF RAIN AS FAR SOUTH AS VENTURA COUNTY
BY MORNING. RAIN IS EXPECTED ACROSS THE REGION SAT, MAINLY IN THE
MORNING ACROSS SLO AND SBA COUNTIES, AND FROM LATE MORNING
THROUGH THE AFTERNOON ACROSS VTU AND L.A. COUNTIES. THE 06Z WRF
ACTUALLY KEEPS THE BULK OF THE RAIN TO THE SOUTH OF SLO COUNTY,
WHICH IS A NEW DEVELOPMENT. ALTHOUGH THAT IS NOT SUPPORTED BY THE
EC OR GFS, IT WILL INTERESTING TO SEE IF THAT TREND CONTINUES
ON THE 12Z RUN.
THERE WILL BE INCREASING INSTABILITY ON SAT, AND THERE IS A SLIGHT
CHANCE OF THUNDERSTORMS IN SBA AND SLO COUNTIES AND IN THE NORTHERN
MOUNTAINS OF L.A. AND VTU COUNTIES IN THE AFTERNOON. DEPENDING
UPON THE EVOLUTION OF THE FRONT, THE SLIGHT CHANCE OF
THUNDERSTORMS MAY HAVE TO BE EXTENDED SOUTHWARD INTO COASTAL AND
VALLEY AREAS OF VTU AND L.A. COUNTIES.
AS THE UPPER LOW PULLS TO THE NORTHEAST OF THE REGION SAT NIGHT,
THE THREAT OF RAIN WILL END, MOSTLY BEFORE MIDNIGHT, BUT SKIES
SHOULD REMAIN PARTLY TO MOSTLY CLOUDY OVERNIGHT INTO SUN MORNING.
SATURDAY WILL BE AN UNUSUALLY COLD DAY FOR LATE APRIL IN
SOUTHWESTERN CALIFORNIA, WITH MAX TEMPS 10 TO 20 DEGREES BELOW
NORMAL IN MOST AREAS, AS POSSIBLY UP TO 25 DEGREES BELOW NORMAL IN
THE ANTELOPE VALLEY AND THE MTNS. IN FACT, SOME DAILY LOW MAXIMUM
TEMPERATURES MAY BE RECORDED ON SAT.
MODELS CONTINUE TO INCREASE RAINFALL TOTALS ACROSS THE REGION, AND
IT NOW LOOKS AS THOUGH THERE WILL BE WIDESPREAD TOTALS OF ONE
THIRD TO TWO THIRDS OF AN INCH, WITH LOCAL TOTALS UP TO AN INCH
FROM SOUTHERN SBA COUNTY THRU CENTRAL AND NORTHERN VENTURA COUNTY
AND POSSIBLY INTO WESTERN L.A. COUNTY.
SNOW LEVELS BE BETWEEN 4500 AND 5500 FEET SAT, AND SEVERAL INCHES
OF SNOW MAY FALL AT ELEVATIONS ABOVE 5500 FEET. WINTER WEATHER
ADVISORIES MAY HAVE TO BE ISSUED FOR THE MOUNTAINS. AT THIS
POINT, IT APPEARS THAT SNOW LEVELS WILL BE TOO HIGH TO BRING
ANY SIGNIFICANT SNOW ACCUMULATIONS TO HIGHER PORTIONS OF
INTERSTATE 5 NEAR THE GRAPEVINE.
THE UPPER LOW WILL MOVE ACROSS NEVADA SAT NIGHT AND EARLY SUN,
THEN INTO NORTHERN UTAH SUN AFTERNOON. SKIES WILL LIKELY BE
PARTLY CLOUDY ACROSS THE AREA SUN, BUT IT LOOKS AS THOUGH ANY
WRAPAROUND SHOWER ACTIVITY WILL REMAIN NORTH AND EAST OF THE
REGION. WITH DECENT HEIGHT RISES, DECREASING ONSHORE GRADIENTS
BETWEEN KLAX AND KDAG, AND SOME INCREASE IN NORTHERLY GRADIENTS,
THERE SHOULD BE SIGNIFICANT WARMING IN MOST AREAS SUN, THOUGH MAX
TEMPS WILL LIKELY STILL BE BELOW NORMAL.
LONG TERM (MON-THU)
24/210 PM.
AN IMPULSE DROPPING SOUTHWARD ON THE BACKSIDE OF THE UPPER LOW
WILL KEEP A TROUGH IN PLACE OVER THE REGION SUN NIGHT/MON.
HOWEVER, A FEW DEGREES OF WARMING IS LIKELY IN MOST AREAS AS
HEIGHTS TREND UPWARD.
UPPER RIDGING WILL BRING MORE SIGNIFICANT WARMING TO THE REGION
TUE WITH HIGHS AT LEAST IN THE LOWER 80S FOR THE WARMER VALLEYS
AND UPPER 60S AND 70S ELSEWHERE ALONG WITH MOSTLY CLEAR SKIES.
HEIGHTS WILL BEGIN TO LOWER WED, AND ONSHORE FLOW WILL INCREASE.
THIS MAY BRING SOME COOLING, ESPECIALLY TO COASTAL AREAS.
AVIATION
25/0205Z.
AT 2351Z AT KLAX, THE MARINE LAYER WAS 1600 FEET DEEP. THE TOP OF
THE INVERSION WAS AROUND 6200 FEET WITH A TEMPERATURE OF 10 C.
HIGH CONFIDENCE IN TAFS FOR KPMD AND KWJF.
MODERATE CONFIDENCE IN REMAINING TAFS WITH VFR TO MVFR CONDITIONS
EXPECTED. FLIGHT CATS MAY FREQUENTLY BOUNCE BETWEEN MVFR AND VFR
WHEN CIGS ARE PRESENT OVERNIGHT.
KLAX...MODERATE CONFIDENCE IN TAF. MVFR CIGS MAY ARRIVE AS EARLY
AS 03Z OR AS LATE AS 08Z. NO SIGNIFICANT EAST WIND COMPONENT
EXPECTED.
KBUR...MODERATE CONFIDENCE IN TAF. TRANSITION TO MVFR CIGS
TONIGHT MAY BE AS EARLY 05Z OR AS LATE AS 09Z.
MARINE
25/213 AM.
FOR THE OUTER WATERS, MODERATE CONFIDENCE IN CURRENT FORECAST.
SMALL CRAFT ADVISORY (SCA) CONDS ARE NOT EXPECTED ON FRIDAY. THEN,
THERE IS A 20% CHANCE OF SCA LEVEL W-NW WIND GUSTS LATE OVERNIGHT
FRI INTO SAT FOR WESTERN PORTIONS OF PZZ673/676. THERE IS A 30%
CHANCE OF SCA LEVEL WIND GUSTS FOR WESTERN PORTIONS OF PZZ676
DURING AFTERNOON/EVE HOURS ON SAT. WIDESPREAD CHANCES FOR SCA
CONDS INCREASE (60-80%) SUN AFTERNOON THRU AT LEAST TUES NIGHT.
FOR THE INNER WATERS NORTH OF POINT SAL, MODERATE TO HIGH
CONFIDENCE IN THE FORECAST. CONDS ARE EXPECTED TO REMAIN BELOW SCA
CRITERIA ON FRI, THEN A 20-30% CHANCE SAT AFTERNOON/EVE. POTENTIAL
FOR WIDESPREAD SCA WINDS INCREASES DURING AFTERNOON/EVE HOURS SUN
THRU TUES (50-80% CHANCE).
FOR THE INNER WATERS SOUTH OF POINT CONCEPTION, MODERATE
CONFIDENCE IN THE FORECAST. CONDITIONS ARE EXPECTED TO REMAIN
BELOW SCA LEVELS ON FRI. THERE IS A 30-40% CHANCE OF SCA LEVEL
WINDS ACROSS THE SANTA BARBARA CHANNEL DURING THE AFTERNOON/EVE
HOURS ON SAT. THEREAFTER, CHANCES INCREASE TO >80% ACROSS THE SBA
CHANNEL ON SUNDAY, WITH A 40% CHANCE NEARSHORE OF MALIBU
COASTLINE. THERE IS A 60% CHANCE OF SCA LEVEL WINDS FOR WESTERN
PORTIONS OF SBA CHANNEL MON AFTERNOON/EVE. MUCH LOWER CHANCES ON
TUE.
ACROSS THE WATERS, SEAS ARE EXPECTED TO REMAIN BELOW SCA
CRITERIA THROUGH THE FORECAST PERIOD.
LOX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...DB/MW/DB
AVIATION...PHILLIPS
MARINE...BLACK
SYNOPSIS...DB/SMITH
WEATHER.GOV/LOSANGELES
EXPERIMENTAL GRAPHICAL HAZARDOUS WEATHER OUTLOOK AT:
HTTPS://WWW.WEATHER.GOV/ERH/GHWO?WFO=LOX
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page