850
FXUS66 KLOX 220348
AFDLOX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
848 PM PDT MON APR 21 2025
SYNOPSIS
21/658 PM.
ONSHORE FLOW WILL STRENGTHEN THROUGH THE WEEK AND BRING A COOLING
TREND THROUGH FRIDAY. NIGHT THROUGH MORNING LOW CLOUDS AND FOG
WILL BE A STAPLE OF THE FORECAST, STRUGGLING TO CLEAR FROM
BEACHES EACH DAY. NIGHT THROUGH MORNING DRIZZLE IS POSSIBLE TOWARD
MID-TO-LATE WEEK AS THE MARINE LAYER DEPTH DEEPENS SUBSTANTIALLY.
GUSTY ONSHORE WINDS ARE POSSIBLE ACROSS THE INTERIOR PORTIONS FOR
THE LATTER HALF OF THE WEEK.
SHORT TERM (MON-THU)
21/847 PM.
***UPDATE***
THE MARINE LAYER IS 1300 FT DEEP AND IS CAPPED BY A STRONG
INVERSION. THERE IS MODERATE ONSHORE FLOW WHICH IS ABOUT 2 MB
STRONG THAN IT WAS 24 HOURS AGO. THESE 2 THINGS HAVE COMBINED TO
BRING LOW CLOUDS BACK INTO THE COASTAL AREAS EARLY THIS EVENING.
THEY WILL ALSO COMBINE TO BRING SLOW TO NO CLEARING TOMORROW.
THE MARINE LAYER AND ONSHORE PUSH HELPED TO LOWER MAX TEMPS 1 TO 3
DEGREES TODAY ACROSS THE COASTS AND VLYS. THE INTERIOR WARMED 2 TO
4 DEGREES UNDER SUNNY SKIES. MAX TEMPS WERE A TALE OF TWO CITIES
WITH CST AND VLYS TEMPS 4 TO 8 DEGREE BLO NORMAL AND THE MTNS AND
INTERIOR CAME IN 4 TO 8 DEGREES ABOVE NORMAL.
TEMPS TOMORROW WILL COOL A FEW DEGREES MORE ACROSS THE CSTS/VLY AS
THE MARINE LAYER CONTINUES TO DOMINATE. THE INTERIOR WILL SEE
SIMILAR TEMPS
FORECAST IS IN PRETTY GOOD SHAPE MADE SMALL ADJUSTMENTS TO TEMPS
AND CLOUDS.
***FROM PREVIOUS DISCUSSION***
A SERIES OF WEAK TO MODERATE UPPER LEVEL TROUGHS MOVING THROUGH
THE WEST COAST THIS WEEK WILL MAINTAIN COOLER THAN NORMAL
TEMPERATURES ACROSS COAST AND COASTAL VALLEYS THIS WEEK. THE
MARINE LAYER DEPTH THIS MORNING WAS AROUND 1400 FEET AND FORECAST
SOUNDINGS INDICATE ADDITIONAL DEEPENING OF 500 TO 1000 FEET EACH
DAY THROUGH AT LEAST THURSDAY. SO WHILE CLOUDS WERE MOSTLY
CONFINED TO THE COASTAL AREAS THIS MORNING, LOW CLOUDS AND FOG
WILL EASILY MAKE IT INTO THE VALLEYS OVERNIGHT TONIGHT AND THEN
AGAIN EACH NIGHT THE REST OF THE WEEK. AND AS USUAL WITH A
DEEPENING MARINE LAYER AND INCREASING ONSHORE FLOW, DAYTIME
TEMPERATURES WILL BE COOLING WITH HIGHS MOSTLY JUST IN THE 60S FOR
COAST/VALLEYS BY NO LATER THAN WEDNESDAY. MAY EVENTUALLY SEE SOME
MORNING DRIZZLE AS THE MARINE LAYER DEEPENS, ESPECIALLY THE LATTER
HALF OF THE WEEK WHEN THE STRONGEST OF THE TROUGHS MOVES THROUGH
THE AREA.
FAR INTERIOR AREAS LIKE THE ANTELOPE VALLEY AND INTERIOR SLO
COUNTY WILL BE COOLING DOWN AS WELL AS SOME OF THAT COOLER
MARITIME AIR PUSHES FARTHER INLAND BUT IT WILL TAKE UNTIL AT LEAST
WEDNESDAY FOR HIGHS THERE TO DROP BELOW NORMAL.
WITH THE INCREASE IN ONSHORE FLOW TO CLOSE TO 9MB TO THE DESERT
EACH AFTERNOON, THERE WILL BE INCREASING WEST TO SOUTHWEST WINDS
THERE GUSTING TO AROUND 40 MPH.
LONG TERM (FRI-MON)
21/215 PM.
THE COOL PATTERN WILL CONTINUE THROUGH THE WEEKEND AS THE
STRONGEST OF THE TROUGHS MOVES THROUGH SATURDAY WHICH WILL LIKELY
BE THE COOLEST DAY. THERE'S STILL QUITE A BIT OF DISAGREEMENT IN
THE MODELS WITH REGARD TO HOW DEEP THE UPPER WILL BE AND WHETHER
THERE WILL BE ANY PRECIPITATION BEYOND JUST THE TYPICAL MORNING
DRIZZLE. THE EPS ENSEMBLES HAVE BEEN PRETTY CONSISTENT THE LAST
FEW RUNS INDICATING AT LEAST A 60-70% CHANCE OF LIGHT RAIN NORTH
OF PT CONCEPTION DROPPING TO AROUND 10-20% IN THE SOUTH. AMOUNTS
WOULD BE UNDER A TENTH OF AN INCH IN MOST AREAS. TEMPERATURES
AGAIN JUST IN THE 60S WITH MINIMAL AFTERNOON CLEARING FOR COAST
AND VALLEYS.
A SLOW WARMING TREND WILL BEGIN SUNDAY BUT HIGH TEMPERATURES WILL
REMAIN BELOW NORMAL THROUGH AT LEAST EARLY NEXT WEEK.
AVIATION
22/0018Z.
AT 2255Z AT KLAX, THE MARINE LAYER WAS 1300 FEET DEEP. THE TOP OF
THE INVERSION WAS 2100 FEET WITH A TEMPERATURES OF 17 C.
MODERATE CONFIDENCE IN TAFS (GOOD CONFIDENCE IN TAFS FOR KPMD AND
KWJF). FLIGHT CAT CHANGE TIMING MAY BE OFF BY +/- 90 MINUTES AND
CIG HGTS OFF BY +/- 200 FT.
KLAX...MODERATE CONFIDENCE IN TAF. FLIGHT CAT CHANGE TIMING MAY
BE OFF BY +/- 90 MINUTES. THERE IS A 15 PERCENT CHC OF 200 FT
CIGS AND A 25 PERCENT CHC OF CIGS NO LOWER THAN 600 FT. NO
SIGNIFICANT EAST WIND COMPONENT IS EXPECTED.
KBUR...MODERATE CONFIDENCE IN TAF. FLIGHT CAT CHANGE TIMING MAY
BE OFF BY +/- 90 MINUTES. THERE IS A 25 PERCENT CHC OF 1/2SM FG
VV002 CONDS 10Z-15Z.
MARINE
21/658 PM.
FOR THE OUTER WATERS, HIGH CONFIDENCE IN CURRENT FORECAST.
THROUGH TONIGHT, THERE IS A 10% CHANCE OF LOCAL SMALL CRAFT
ADVISORY (SCA) LEVEL WIND GUSTS, MAINLY AROUND POINT CONCEPTION.
FOR TUESDAY, THERE IS A 30% CHANCE OF SCA LEVEL WINDS IN THE
NORTHWESTERN OUTER WATERS IN THE AFTERNOON AND EVENING. FOR
WEDNESDAY THROUGH SATURDAY, THERE IS A 50-70% CHANCE OF SCA LEVEL
WINDS ACROSS MUCH OF THE OUTER WATERS, ESPECIALLY IN THE
AFTERNOON AND OVERNIGHT HOURS.
FOR THE INNER WATERS NORTH OF POINT SAL, HIGH CONFIDENCE IN
CURRENT FORECAST. TONIGHT THROUGH TUESDAY, HIGH CONFIDENCE IN
WINDS AND SEAS REMAINING BELOW SCA LEVELS. FOR WEDNESDAY THROUGH
SATURDAY, THERE IS A 30-50% CHANCE OF SCA LEVEL WINDS, MAINLY IN
THE LATE AFTERNOON THROUGH EVENING HOURS.
FOR THE INNER WATERS SOUTH OF POINT CONCEPTION, HIGH CONFIDENCE
IN CURRENT FORECAST. TONIGHT THROUGH FRIDAY, HIGH CONFIDENCE IN
WINDS AND SEAS REMAINING BELOW SCA LEVELS ACROSS MOST AREAS. THE
ONLY EXCEPTION WILL BE THE WESTERN HALF OF THE SANTA BARBARA
CHANNEL WHERE THERE IS A 30-40% CHANCE OF SCA LEVEL WINDS
WEDNESDAY AND THURSDAY, AND A 40-50% CHANCE FRIDAY AND SATURDAY,
MAINLY DURING THE LATE AFTERNOON THROUGH EVENING HOURS.
CHANCES FOR SCA CONDS INCREASE OVER THE WEEKEND FOR THE ENTIRE
COASTAL WATERS.
LOX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...MW/RORKE
AVIATION...RORKE
MARINE...LEWIS/SMITH
SYNOPSIS...HALL/SMITH
WEATHER.GOV/LOSANGELES
EXPERIMENTAL GRAPHICAL HAZARDOUS WEATHER OUTLOOK AT:
HTTPS://WWW.WEATHER.GOV/ERH/GHWO?WFO=LOX
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