349
FXUS66 KLOX 210546
AFDLOX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
946 PM PST WED NOV 20 2024
SYNOPSIS
20/830 PM.
FAIR SKIES AND DRY WEATHER WILL CONTINUE THROUGH THURSDAY AND MOST
AREAS WILL SEE SOME WARMING AS WELL. RAIN CHANCES WILL DEVELOP
ALONG THE CENTRAL COAST FRIDAY EVENING THEN ACROSS LOS ANGELES
AND VENTURA COUNTIES SATURDAY. ANOTHER ROUND OF RAIN IS EXPECTED
LATER SUNDAY INTO MONDAY AND POSSIBLY AROUND THANKSGIVING.
SHORT TERM (WED-SAT)
20/829 PM.
***UPDATE***
QUIET CONDITIONS ARE EXPECTED TONIGHT INTO THURSDAY FOR MOST OF
THE AREA, PRECEDING AN EXTENDED PERIOD OF MAINLY LIGHT RAIN. THE
MAIN ISSUE FOR THE OVERNIGHT PERIOD IS COLD TEMPERATURES, WITH A
FROST ADVISORY NOW IN EFFECT FOR THE OJAI AND AGOURA VALLEYS FROM
LATE TONIGHT INTO FRIDAY MORNING. OTHER AREAS WILL ALSO SEE COLD
OVERNIGHT TEMPERATURES, INCLUDING THE ANTELOPE VALLEY AND OTHER
INTERIOR VALLEYS. WINDS WILL BE MAINLY LIGHT ACROSS THE AREA
TONIGHT, AIDING IN EFFICIENT COOLING. IN ADDITION, THE AIR MASS IS
VERY DRY, WITH HUMIDITIES LIKELY TO DROP INTO THE SINGLE DIGITS,
WHICH ALSO HELPS WITH COOLING OF THE AIR MASS.
DAYTIME HIGHS THURSDAY WILL BE SIMILAR TO A FEW DEGREES WARMER
THAN TODAY, WITH UPPER 60S TO UPPER 70S AWAY FROM THE COAST, AND
60S FOR COASTAL AREAS. MAINLY LIGHT WINDS ARE EXPECTED WITH MOSTLY
SUNNY SKIES ACROSS THE AREA.
***FROM PREVIOUS DISCUSSION***
AN IMPRESSIVELY LARGE AND STRONG CYCLONE CONTINUES TO SPIN JUST
WEST OF VANCOUVER ISLAND. THE CENTER HAS MOVED VERY LITTLE THE
LAST 24 HOURS, AND IS EXPECTED TO SPIN AROUND OFFSHORE OF THE
PACIFIC NORTHWEST THROUGH EARLY NEXT WEEK. WHILE THERE REMAINS
QUITE A LARGE SPREAD IN THE NUMBER OF OUTCOMES WITH THIS WEAK
ATMOSPHERIC RIVER, WITH THE UPPER LOW STAYING MOSTLY WELL NORTH
OF THE AREA, THE MOST LIKELY SCENARIO IS A GENERALLY BENEFICIAL
RAIN FOR THE AREA WITH ONLY ABOUT A 5-10 PERCENT CHANCE OF RAINS
HEAVY ENOUGH TO GENERATE ANY SIGNIFICANT FLOODING.
FOR THIS WEEKEND THERE APPEARS TO BE TWO DISTINCT FRONTAL BOUNDARIES
COMING THROUGH, SEPARATED BY AROUND 24-36 HOURS. BASED ON THE 12Z
ENSEMBLES, THE FIRST ONE WILL ARRIVE LATER FRIDAY ALONG THE
CENTRAL COAST, AND SATURDAY FOR AREAS TO THE SOUTH. THIS WILL BE
THE WEAKER OF THE TWO WITH MOST OF THE RAIN FALLING IN A 3-6 HOUR
PERIOD. FOR SLO AND NORTHERN SANTA BARBARA COUNTIES THERE WILL BE
MINOR SOUTHWEST UPSLOPE COMPONENT THAT WILL HELP GENERATE SLIGHTLY
HIGHER RAIN RATES, WITH RAIN AMOUNTS EXPECTED TO BE AROUND A HALF
INCH, EXCEPT UP TO AROUND AND INCH IN THE NORTHWEST COASTAL
MOUNTAINS. RAIN RATES GENERALLY A TENTH OF AN INCH OR LESS EXCEPT
AROUND A QUARTER INCH IN UPSLOPE AREAS. FOR SOUTHERN AREAS AMOUNTS
EXPECTED TO BE A QUARTER INCH OR LESS. SNOW LEVELS WILL BE OVER
8000 FEET SO NO SNOW ISSUES EXPECTED.
LONG TERM (SUN-WED)
20/220 PM.
THE SECOND PHASE OF THIS STORM IS EXPECTED LATER SUNDAY INTO
MONDAY. WHILE THE ENSEMBLES ARE ACTUALLY INDICATING SLIGHTLY
LOWER PRECIPITABLE WATERS WITH THIS ONE, MOST OF THE ENSEMBLES
SHOW THE UPPER LOW MOVING FARTHER SOUTH WHICH SHOULD BRING MORE
ENERGY THIS WAY. CONFIDENCE REMAINS ON THE LOWER SIDE BUT MOST OF
THE ENSEMBLES SHOW MORE RAIN WITH THIS SECOND WAVE OF PRECIP, BUT
STILL MOSTLY BENEFICIAL RAIN WITH AROUND A 10 PERCENT OF ANY
SIGNIFICANT FLOODING. THE MOST LIKELY OUTCOME IS AN INCH OR LESS
LA/VENTURA COUNTIES AND 1-2" SLO/SB COUNTIES. ONCE AGAIN SNOW
LEVELS WILL BE OVER 8000 FEET.
EVEN LOWER CONFIDENCE AFTER MONDAY NEXT WEEK AS THE MODELS ARE
REALLY STRUGGLING WITH THE UPPER LEVEL PATTERN. ROUGHLY 50%
PERCENT OF THE ENSEMBLES SHOW ANOTHER SYSTEM COMING THROUGH
THURSDAY OR FRIDAY, AND A FEW OF THOSE ARE QUITE HEAVY.
AVIATION
21/0536Z.
AT 0447Z AT KLAX, THERE WAS NO MARINE LAYER. THERE WAS A SFC BASED
INVERSION WITH A TOP OF THE INVERSION WAS AT 1200 FT AND A
TEMPERATURE OF 19 C.
OVERALL, HIGH CONFIDENCE IN VFR FLIGHT CONDS AT MOST SITES THRU
THE PERIOD WITH NO SIG WIND ISSUES. THERE IS A 30% % CHANCE OF
MVFR CONDS FROM 11Z TO 15Z AT KLGB.
KLAX...HIGH CONFIDENCE IN 00Z TAF. NO SIGNIFICANT EAST WIND
COMPONENT EXPECTED.
KBUR...HIGH CONFIDENCE IN 00Z TAF.
MARINE
20/825 PM.
FOR THE OUTER WATERS, BUOY OBSERVATIONS CONFIRM THAT SMALL CRAFT
ADVISORY (SCA) LEVEL SEAS ARE CURRENTLY IMPACTING PZZ670 AND
PZZ673. THESE CONDS ARE EXPECTED TO PERSIST THROUGH THURSDAY
EVENING. THERE IS A 30-40% CHANCE OF SCA LEVEL SEAS FOR WESTERN
PORTIONS OF THE SOUTHERNMOST ZONE (PZZ676) DURING THE
AFOREMENTIONED PERIOD, BUT ANY HIGH SEAS MOST LIKELY WILL NOT BE
WIDESPREAD ENOUGH TO WARRANT A SCA. WINDS ARE EXPECTED TO REMAIN
SUB ADVISORY THROUGH THE WEEKEND, WITH THE EXCEPTION FOR THE
NORTHWEST PORTION OF THE NORTHERN OUTER WATERS THIS AFTERNOON THRU
FRIDAY.
FOR THE INNER WATERS N OF PT. SAL, THERE IS A 70-80% CHANCE OF
SCA LEVEL SEAS DEVELOPING THIS EVENING/NIGHT AND LASTING INTO
THURSDAY, ESPECIALLY IN FAR WESTERN PORTIONS OF PZZ645. HOWEVER,
WINDS WILL REMAIN BELOW SCA LEVELS THROUGH THE WEEKEND.
FOR THE INNER WATERS SOUTH OF POINT CONCEPTION, SUB ADVISORY LEVEL
CONDITIONS ARE EXPECTED THROUGH THE WEEKEND. WIND GUSTS UP TO 20
KT ARE POSSIBLE ACROSS THE SAN PEDRO CHANNEL THURSDAY AFTERNOON
THROUGH EVENING, BUT RELATIVELY BENIGN CONDITIONS CAN BE EXPECTED
ELSEWHERE.
RAIN SHOWERS ARE LIKELY IN THE COASTAL WATERS, BEGINNING IN THE
NORTHERN WATERS FRIDAY MORNING, PROGRESSING SOUTH TO INCLUDE ALL
AREAS BY SATURDAY MORNING. PERIODIC SHOWERS ARE LIKELY THROUGH
THE WEEKEND.
LOX WATCHES/WARNINGS/ADVISORIES
CA...HIGH SURF ADVISORY IN EFFECT UNTIL 10 AM PST THURSDAY FOR
ZONES 340-346. (SEE LAXCFWLOX).
FROST ADVISORY IN EFFECT FROM 2 AM TO 8 AM PST THURSDAY FOR
ZONES 357-371. (SEE LAXNPWLOX).
PZ...SMALL CRAFT ADVISORY IN EFFECT UNTIL 10 AM PST THURSDAY FOR
ZONE 645. (SEE LAXMWWLOX).
SMALL CRAFT ADVISORY IN EFFECT UNTIL 9 PM PST THURSDAY FOR
ZONES 670-673. (SEE LAXMWWLOX).
PUBLIC...MW/SMITH
AVIATION...RORKE
MARINE...BLACK
SYNOPSIS...MW/SMITH
WEATHER.GOV/LOSANGELES
EXPERIMENTAL GRAPHICAL HAZARDOUS WEATHER OUTLOOK AT:
HTTPS://WWW.WEATHER.GOV/ERH/GHWO?WFO=LOX
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