099
FXUS66 KLOX 211755
AFDLOX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1055 AM PDT MON APR 21 2025
SYNOPSIS
21/920 AM.
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 (TDY-WED)
21/405 AM.
ONSHORE FLOW IS STRENGTHENING EARLY THIS MORNING AS BROAD WEAK
TROUGHING DEVELOPS OVER THE WEST COAST. SURFACE PRESSURE GRADIENTS
ARE TRENDING ABOUT A MILLIBAR MORE STRONGLY ONSHORE. CLOUDS ARE
WELL-ENTRENCHED ALONG THE CENTRAL COAST BUT STRUGGLING TO FORM
INSIDE THE SOUTHERN CALIFORNIA BIGHT AND ALONG THE SOUTH COAST OF
CALIFORNIA DUE TO HIGH CLOUDINESS ALOFT PLAYING TRICKS ON THE
MARINE LAYER DEPTH. AS THE MORNING PROGRESSES, HIGH CLOUDS SHOULD
LESSEN IN COVERAGE AND ALLOW FOR BETTER LOW CLOUDS COVERAGE INTO
THE BIGHT AND THE LOS ANGELES AND VENTURA COUNTY COAST.
ONSHORE FLOW WILL CONTINUE TO STRENGTHEN THROUGH THE PERIOD AS
WEAK TROUGHING WILL REMAIN ANCHORED OFF THE WEST COAST. LOW CLOUDS
AND FOG WILL BECOME MORE ENTRENCHED TONIGHT AND INTO TUESDAY
MORNING AS ONSHORE FLOW STRENGTHENS. THE MARINE LAYER DEPTH WILL
DEEPEN EACH NIGHT AND MORNING, DEEPENING FROM AROUND 700 FEET AT
KLAX THIS MORNING TO NEAR 2000 FEET DEEP BY TUESDAY MORNING, THEN
TO NEAR 2500 FEET DEEP BY WEDNESDAY MORNING. CLOUDS SHOULD MAKE A
RETURN TO THE LOS ANGELES AND VENTURA COUNTY VALLEYS TONIGHT AND
INTO TUESDAY MORNING. PATCHY LATE NIGHT AND EARLY MORNING DRIZZLE
CANNOT BE RULED OUT TONIGHT AND INTO TUESDAY MORNING, BUT THERE
IS A HIGHER CHANCE ON TUESDAY NIGHT AND INTO WEDNESDAY MORNING.
WITH THE STRONGER ONSHORE TRENDS TAKING SHAPE EACH DAY, LOW
CLOUDS AND FOG WILL LIKELY STRUGGLE TO CLEAR FROM THE BEACHES AND
IMMEDIATE COAST OVER THE COMING DAYS. AS A RESULT, TEMPERATURES
WILL BE BELOW SEASONAL NORMALS FOR THIS TIME OF YEAR, ESPECIALLY
AT THE BEACHES AND NEAR THE COAST.
LONG TERM (THU-SUN)
21/402 AM.
ONSHORE FLOW AND A DEEP MARINE LAYER WILL BE THE MAIN STORY
THROUGH FRIDAY. NIGHT THROUGH MORNING LOW CLOUDS AND FOG WITH
DRIZZLE WILL LIKELY PUSH WELL INTO THE COASTAL SLOPES OF THE
MOUNTAINS. THE FORECAST ENSEMBLES ALL ADVERTISE MUCH COOLER
CONDITIONS LINGERING WITH TEMPERATURES BELOW SEASONAL NORMALS INTO
LATE WEEK. GUSTY ONSHORE WINDS, EACH AFTERNOON AND EVENING ACROSS
THE INTERIOR PORTION, COULD REACH ADVISORY LEVELS IN THE
FOOTHILLS OF THE ANTELOPE VALLEY, ESPECIALLY IF 10 MB ONSHORE
GRADIENTS DEVELOP.
WHILE THE FORECAST ENSEMBLES AGREE WELL THROUGH FRIDAY, THE
ENSEMBLE SPREAD STARTS TO WIDEN OVER NEXT WEEKEND AND INTO NEXT
WEEK. CLUSTER ANALYSIS FAVORS TROUGHING LINGERING OVER THE REGION
INTO FRIDAY OR SATURDAY, THEN THE CLUSTERS START TO DIVERGE.
THEREAFTER, THE MOST LIKELY SCENARIO SUGGEST RIDGING ALOFT
BUILDING, GIVING A 56 PERCENT CHANCE OF OCCURING. EPS FORECAST
ENSEMBLES LEAN TOWARD WARMING FOR NEXT WEEKEND IN THE MAXIMUM
TEMPERATURE MEANS. THE FORECAST GOES WITH NBM VALUES FOR THE
CURRENT TIME.
AVIATION
21/1754Z.
AT 1708Z AT KLAX, THE MARINE INVERSION WAS AROUND 1500 FEET DEEP.
THE TOP OF THE INVERSION WAS 2900 FEET WITH A TEMPERATURES OF 15
DEGREES CELSIUS.
LOW CONFIDENCE IN MINIMUM FLIGHT CAT AT KBUR/KVNY, BUT HIGH
CONFIDENCE IN CIGS ARRIVING LATER TONIGHT. ARRIVAL TIME MAY BE OFF
+/- 3 HOURS AND MINIMUM FLIGHT CAT MAY BE OFF BY 1 FLIGHT CAT.
MODERATE TO HIGH CONFIDENCE IN REMAINING TAFS. THERE IS A 20-40%
CHANCE CHANCE FOR MVFR CONDS TO BE MINIMUM FLIGHT CAT AT VENTURA
AND LA COUNTY COASTAL SITES THROUGH THE PERIOD ONCE CIGS ARRIVE.
MVFR CIGS MAY BOUNCE IN AND OUT THIS AFTERNOON/EVENING, BUT CIGS
MAY ARRIVE AND REMAIN IN PLACE THROUGH TOMORROW MORNING AS EARLY
AS 00Z.
KLAX...MODERATE CONFIDENCE IN 18Z TAF. MVFR CIGS MAY BOUNCE IN AND
OUT AT ANY POINT THIS AFTERNOON/EVENING, WITH A 40% CHANCE CIGS
TO ARRIVE AS EARLY AS 00Z AND REMAIN IN PLACE THROUGH THE MORNING.
THERE IS A 30% CHANCE CIGS REMAIN OVC010 OR HIGHER THROUGH THE
PERIOD ONCE CIGS ARRIVE. NO SIGNIFICANT EAST WIND COMPONENT IS
EXPECTED.
KBUR...MODERATE CONFIDENCE IN 18Z TAF. HIGH CONFIDENCE IN CIGS
REACHING THE TERMINAL LATE TONIGHT, BUT LOW CONFIDENCE IN MINIMUM
FLIGHT CAT. ARRIVAL TIME MAY BE OFF +/- 3 HOURS. 20% CHANCE FOR
VV001-002 AND/OR VSBYS LESS THAN 1/2SM ONCE CIGS ARRIVE.
MARINE
21/758 AM.
FOR THE OUTER WATERS, MODERATE TO HIGH CONFIDENCE IN CURRENT
FORECAST. THROUGH TONIGHT, THERE IS A 10-20% CHANCE OF SMALL CRAFT
ADVISORY (SCA) LEVEL WINDS, MAINLY AROUND POINT CONCEPTION. FOR
TUESDAY, THERE IS A 20-40% CHANCE OF SCA LEVEL WINDS ACROSS ALL
THE OUTER WATERS, WITH HIGHEST CHANCES IN THE NORTHWESTERN OUTER
WATERS. FOR WEDNESDAY THROUGH FRIDAY, THE CHANCES FOR SCA LEVEL
WINDS INCREASE TO 60-80%.
FOR THE INNER WATERS NORTH OF POINT SAL, MODERATE TO HIGH
CONFIDENCE IN CURRENT FORECAST. TODAY THROUGH TUESDAY, HIGH
CONFIDENCE IN WINDS AND SEAS REMAINING BELOW SCA LEVELS. FOR
WEDNESDAY THROUGH FRIDAY, THERE IS A 50-60% CHANCE OF SCA LEVEL
WINDS, MAINLY IN THE LATE AFTERNOON AND EVENING HOURS.
FOR THE INNER WATERS SOUTH OF POINT CONCEPTION, MODERATE TO HIGH
CONFIDENCE IN CURRENT FORECAST. TODAY 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 40-60% CHANCE OF SCA LEVEL
WINDS WEDNESDAY THROUGH FRIDAY, MAINLY DURING THE LATE AFTERNOON
THROUGH EVENING HOURS.
LOX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...HALL
AVIATION...LEWIS
MARINE...RAT/LEWIS
SYNOPSIS...HALL
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