478
FXUS66 KLOX 181702
AFDLOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
902 AM PST THU DEC 18 2025
SYNOPSIS
17/201 PM.
WELL ABOVE NORMAL TEMPERATURES WILL CONTINUE AWAY FROM THE COAST
THROUGH FRIDAY. UNSETTLED WEATHER IS POSSIBLE THIS WEEKEND ALONG
THE CENTRAL COAST, SPREADING TO ALL AREAS WITH A POTENTIALLY
SIGNIFICANT STORM NEAR THE MIDDLE PART OF NEXT WEEK.
SHORT TERM (TDY-SAT)
18/852 AM.
***UPDATE***
LOW CLOUDS AND FOG IN SOME COASTAL AREAS WAS BEGINNING TO BURN
OFF OR PUSH OFFSHORE THIS MORNING. BREEZY NORTHERLY WINDS ACROSS
THE MOUNTAINS AND FOOTHILLS CONTINUED TO BE GENERALLY BELOW
ADVISORY LEVELS. ADDED SOME PARTLY CLOUDY WORDING TO FORECAST AS
HIGH CLOUDS HAVE FILLED INTO THE REGION MORE THAN ANTICIPATED.
OUR FOCUS CONTINUES TO BE ON THE PERIOD OF UNSETTLED WEATHER NEXT
WEEK, ESPECIALLY TUESDAY THROUGH THURSDAY OR FRIDAY. WE'LL TAKE A
CLOSER LOOK AT THE DETAILS TODAY - BUT A QUICK LOOK THIS MORNING
INDICATES THAT ACTIVE WEATHER MAY STICK AROUND FOR A COUPLE OF
DAYS BEYOND THE ATMOSPHERIC RIVER EVENT (LATE TUESDAY THROUGH
EARLY THURSDAY) OR POTENTIALLY INTO NEXT WEEKEND.
STAY TUNED TO THE WEATHER, ESPECIALLY FOR THOSE TRAVELING OR
PLANNING OUTDOOR ACTIVITIES THIS HOLIDAY SEASON.
***FROM PREVIOUS DISCUSSION***
THE GRADIENTS ARE TRANSITIONING FROM A STRONG N PUSH TO MORE OF A
NE PUSH. THE WINDS ARE SUBSIDING SOME AND SHOULD MOSTLY BE BELOW
ADVISORY CRITERIA BY DAWN. THE OFFSHORE WINDS HAVE PUSHED ALL OF
THE COASTAL LOW CLOUDS AWAY SAVE FOR THE WESTERN SBA COUNTY
BEACHES. THE LONG BEACH AREA MAY SEE SOME LOW CLOUDS AND DENSE FOG
FOR A FEW HOURS THIS MORNING AS THE OFFSHORE FLOW IN THAT AREA IS
WEAKEST. THE OTHERWISE SUNNY SKIES WILL TEAM UP WITH THE OFFSHORE
FLOW TO BRING WARMING TO MOST OF THE AREA, BUT ESP THE VTA/LA
COUNTY CSTS/VLYS WHERE 8 TO 12 DEGREES OF WARMING IS LIKELY. LOOK
FOR MAX TEMPS IN THE 70S ACROSS THE CSTS AND 80S IN THE VLYS OR 12
TO 18 DEGREES OVER NORMAL.
ON FRIDAY THE RIDGE WILL BE PUSHED TO THE SOUTH AND FLAT WESTERLY
FLOW SETS UP OVER THE AREA. HGTS WILL FALL TO ABOUT 585 DAM
(STILL WELL ABOVE NORMAL). LOW CLOUDS WILL BE SIMILAR TO WEDNESDAY
AND PRETTY MUCH CONFINED TO THE LONG BEACH AREA. MUCH WEAKER
OFFSHORE FLOW AT THE SFC WILL LEAD TO 3 TO 6 DEGREES OF COOLING
ACROSS THE CSTS/VLYS. THE LACK OF COOL AIR ADVECTION FROM THE
SAN JOAQUIN VLY WILL LEAD TO 2 TO 4 DEGREES OF WARMING ACROSS THE
INTERIOR.
FLAT WESTERLY FLOW CONTINUES OVER THE AREA ON SATURDAY. HGTS WILL
DIP DOWN TO 582 DAM. ONSHORE FLOW TO THE EAST WILL INCREASE FROM 1
MB IN THE MORNING TO ABOUT 3 MB IN THE AFTERNOON, THE OFFSHORE
FLOW FROM THE NORTH WILL BE 3 MB WEAKER IN THE AFTERNOON COMPARED
TO FRIDAY. THE ONSHORE FLOW AND FALLING HGTS WILL BRING SOME
COASTAL LOW CLOUDS TO THE AREA IN THE MORNING. AT THE SAME TIME THE
SOUTHERN EDGE OF AN ATMOSPHERIC RIVER (AR) AFFECTING THE NORTHERN
PORTION OF THE STATE WILL MOVE SOUTH ENOUGH TO SOUTH TO BRING
MOSTLY CLOUDY SKIES TO MOST OVER THE AREA SAVE FOR LA COUNTY WHICH
WILL END UP PARTLY CLOUDY. THE AR COULD (20 PERCENT CHC) BRING
SOME LIGHT RAIN TO SLO COUNTY. THE COOLING TREND WILL CONTINUE AS
FALLING HGTS AND BETTER ONSHORE FLOW COMBINE TO LOWER MOST TEMPS 3
TO 6 DEGREES. THE CENTRAL COAST WILL BE THE EXCEPTION WITH LITTLE
CHANGE IN TEMPS. MAX TEMPS, HOWEVER, WILL REMAIN ABOVE NORMAL
(3 TO 6 DEGREES CSTS, 5 TO 10 DEGREES VLYS AND 10 TO 15 DEGREES
MTNS AND FAR INTERIOR).
LONG TERM (SUN-WED)
18/258 AM.
SUNDAY AND MONDAY WILL BE FAIRLY SIMILAR DAYS. THE UPPER FLOW
PATTERN WILL SLOWLY TILT MORE AND MORE INTO A SW TO NE DIRECTION
ON SUNDAY AS THE AR SYSTEM SAGS A LITTLE MORE TO THE SOUTH. A
SLIGHT CHC OR CHC (20 TO 30 PERCENT) OF RAIN WILL DEVELOP OVER SLO
AND WESTERN SBA COUNTIES. OTHER AREAS WILL JUST SEE INCREASING
CLOUDS. RAINFALL TOTALS DURING THE TWO DAY PERIOD WILL MOST
LIKELY BE UNDER A TENTH OF AN INCH WITH PERHAPS THE EXCEPTION OF
THE FAR NW TIP OF SLO COUNTY WHICH COULD SEE MORE. SKIES WILL
TURN MOSTLY CLOUDY SUNDAY AND WILL PERSIST THROUGH MONDAY. MAX
TEMPS WILL FALL 2 TO 4 DEGREES ACROSS ALMOST ALL OF THE AREA
SUNDAY AND THEN WILL CHANGE LITTLE ON MONDAY. MAX TEMPS WILL
REMAIN 3 TO 6 DEGREES OVER NORMALS FOR THE CSTS AND VLYS.
TUESDAY ROMAINES THE DAY OF TRANSITION. THE AR WILL SAG SOUTH AND
THE FLOW WILL BECOME EVEN MORE SOUTHWESTERLY. RAIN CHANCES WILL
OVERSPREAD THE ENTIRE AREA. RAIN CHANCES HAVE INCREASED WITH THE
LATEST FORECAST AND NOW SIT AROUND 40 PERCENT FOR LA COUNTY, 50
PERCENT FOR VTA COUNTY, 50 TO 60 PERCENT FOR SBA COUNTY AND 60 TO
70 PERCENT FOR SLO COUNTY. THE FORECAST RAINFALL AMOUNTS HAVE ALSO
BEEN INCREASED. SBA AND SLO COUNTIES WILL NOW LIKELY SEE A HALF
INCH TO AN INCH OF RAIN, WHILE A QUARTER INCH TO A HALF INCH IS
POSSIBLE FOR VTA AND LA COUNTIES.
THERE HAS BEEN A SLIGHT CHANGE IN THE CURRENT THINKING FOR THE
WED/THU STORM. BOTH THE EC AND ESP THE GFS (AS WELL AS MOST
ENSEMBLES AND THE AI ENHANCED MDLS) ARE NOW SPEEDING UP THE SYSTEM
(HENCE THE WETTER TUESDAY FCST). THIS FORECAST (WHICH VERY WELL
MIGHT CHANGE SINCE IT IS 7 TO 8 DAYS AWAY) NOW CALL FOR THE BULK
OF THE RAIN TO FALL WEDNESDAY THROUGH THURSDAY (CHRISTMAS)
MORNING. VERY PRELIMINARY (AND SUBJECT TO CHANGE) RAINFALL TOTALS
FOR THE WED/THU TIME PERIOD CALL FOR 2 TO 4 INCHES OF RAIN
CSTS/VLYS, 4 TO 6 INCHES ACROSS THE MTNS AND 1 TO 2 INCHES FOR THE
INTERIOR SECTIONS. IT IS TOO EARLY TO GET A HANDLE ON RAINFALL
RATE PREDICTIONS. SNOW LEVELS WILL BE OVER 8000 FT BUT WILL START
TO FALL LATER THURSDAY.
MODEL AGREEMENT FALLS OFF PRETTY RAPIDLY AFTER THURSDAY, BUT THERE
IS A POTENTIAL FOR ANOTHER SYSTEM OVER THE WEEKEND OF THE 27TH AND
28TH.
AVIATION
18/1701Z.
AT 1630Z AT KLAX, THE MARINE LAYER DEPTH WAS AROUND 500 FEET.
THE TOP OF THE INVERSION WAS 2600 FEET WITH A TEMPERATURE OF
24 DEGREES CELSIUS.
FOR 18Z TAF PACKAGE, HIGH CONFIDENCE IN KSBP...KSBA...KOXR...KCMA
KBUR...KVNY...KPMD AND KWJF. FOR KSMX...KLAX...KLGB AND KLGB,
MODERATE CONFIDENCE IN 18Z TAFS AS TIMING OF FLIGHT CATEGORY
CHANGES WITH MARINE LAYER COULD BE +/- 3 HOURS OF CURRENT
FORECASTS.
KLAX...OVERALL...MODERATE CONFIDENCE IN 18Z TAF. TIMING OF FLIGHT
CATEGORY CHANGES COULD BE +/- 3 HOURS OF CURRENT FORECASTS. NO
SIGNIFICANT EASTERLY WIND COMPONENT IS EXPECTED.
KBUR...HIGH CONFIDENCE IN 18Z TAF.
MARINE
18/720 AM.
FOR THE OUTER WATERS, MODERATE TO HIGH CONFIDENCE IN CURRENT
FORECAST. TODAY THROUGH FRIDAY EVENING, SMALL CRAFT ADVISORY (SCA)
LEVEL WINDS WILL CONTINUE ACROSS ALL OF THE OUTER WATERS. FOR
FRIDAY NIGHT AND SATURDAY, THE SCA LEVEL WINDS WILL CONTINUE
ACROSS PZZ673/676. ADDITIONALLY, THERE WILL BE 20-30% CHANCE OF
GALE FORCE WIND GUSTS AROUND POINT CONCEPTION TODAY THROUGH
SATURDAY. FOR SUNDAY THROUGH MONDAY, WINDS AND SEAS WILL REMAIN
BELOW SCA LEVELS FOR ALL OF THE OUTER WATERS.
FOR THE INNER WATERS NORTH OF POINT SAL, HIGH CONFIDENCE IN
CURRENT FORECAST. SCA LEVEL WINDS WILL DEVELOP TODAY AND FRIDAY
DURING THE AFTERNOON AND EVENING HOURS. FOR SATURDAY THROUGH
SUNDAY, WINDS AND SEAS WILL REMAIN BELOW SCA LEVELS.
FOR THE INNER WATERS SOUTH OF POINT CONCEPTION, MODERATE TO HIGH
CONFIDENCE IN CURRENT FORECAST. TODAY THROUGH FRIDAY, THERE IS A
30-40% CHANCE OF SCA LEVEL WINDS ACROSS THE WESTERN HALF OF THE
SANTA BARBARA CHANNEL. OTHERWISE, HIGH CONFIDENCE IN WINDS AND
SEAS REMAINING BELOW SCA FOR THE SOUTHERN INNER WATERS THROUGH
MONDAY.
LOX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT UNTIL 9 PM PST THIS EVENING
FOR ZONE 645. (SEE LAXMWWLOX).
SMALL CRAFT ADVISORY IN EFFECT UNTIL 9 PM PST FRIDAY FOR ZONE
670. (SEE LAXMWWLOX).
SMALL CRAFT ADVISORY IN EFFECT UNTIL 3 AM PST SATURDAY FOR
ZONES 673-676. (SEE LAXMWWLOX).
PUBLIC...RORKE
AVIATION...RAT
MARINE...RAT
SYNOPSIS...RM/JLD
WEATHER.GOV/LOSANGELES
EXPERIMENTAL GRAPHICAL HAZARDOUS WEATHER OUTLOOK AT:
HTTPS://WWW.WEATHER.GOV/ERH/GHWO?WFO=LOX
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