096
FXUS66 KLOX 171657
AFDLOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
957 AM PDT WED SEP 17 2025
SYNOPSIS
17/814 AM.
IT WILL BE WARM AND MUGGY THROUGH FRIDAY AS REMNANTS OF TROPICAL
STORM MARIO MOVE INTO THE AREA. TEMPERATURES WILL COOL THROUGH THE
PERIOD BUT HUMIDITIES WILL BE MUCH HIGHER THAN NORMAL. RAIN AND
THUNDERSTORM CHANCES WILL BEGIN WEDNESDAY NIGHT AND CONTINUE INTO
AT LEAST EARLY FRIDAY. OVER THE WEEKEND INTO EARLY NEXT WEEK THERE
IS SLIGHT CHANCE OF SHOWERS AS ADDITIONAL MOISTURE FROM THE SOUTH
ARRIVES. TEMPERATURES WILL BE NEAR NORMAL AND THE MUGGY WEATHER
WILL CONTINUE INTO EARLY NEXT WEEK.
SHORT TERM (TDY-FRI)
17/826 AM.
***UPDATE***
MOISTURE FROM MARIO IS ALREADY MOVING INTO THE AREA, A LITTLE
AHEAD OF SCHEDULE. AS A RESULT OVERNIGHT LOWS LAST NIGHT WERE
WELL INTO THE 60S AND EVEN LOW 70S. AND ALREADY SEEING NUMEROUS
LIGHTNING STRIKES, SO FAR MOSTLY OVER THE OCEAN, BUT THERE IS
CURRENTLY A DEVELOPING STORM IN THE SOUTHERN SAN LUIS OBISPO
MOUNTAINS WITH A LOT OF LIGHTNING BUT PROBABLY NOT A LOT OF RAIN
REACHING THE GROUND.
OVERALL THE SYSTEM DOES APPEAR TO BE DEVELOPING QUICKER AND LATEST
CAMS ARE INDICATING THAT MOST OF THE PRECIP MAY MOVE IN OVERNIGHT
TONIGHT. RAIN RATES AND AMOUNTS STILL ON TRACK FROM THE PREVIOUS
FORECASTS.
WITH THE MOISTURE INCREASING TODAY AND ADDED CLOUDS BY AFTERNOON
TEMPERATURES ARE EXPECTED TO TOP OUT COOLER THAN YESTERDAY BUT
WITH ADDED HUMIDITY. NOT EXPECTING TO NEED HEAT ADVISORIES BUT IT
WILL BE VERY WARM AND MUGGY.
***FROM PREVIOUS DISCUSSION***
FOR THE NEXT THREE DAYS SRN CA IS GOING TO FEEL LIKE FLORIDA WEST.
MOISTURE FROM THE REMNANTS OF TROPICAL STORM MARIO IS MOVING INTO
THE FORECAST AREA. THERE IS ALREADY ONE BAND OF TSTMS IN THE OUTER
WATERS TO THE SW OF PT CONCEPTION. MOISTURE WILL CONTINUE TO
INCREASE UNTIL IT REACHES ITS PEAK (AROUND 1.9") IN THE LATE
MORNING ON THURSDAY. THE CHC OR SHOWERS WILL INCREASE THROUGH THE
DAY TODAY BUT MOST OF THE SHOWER AND TSTM ACTIVITY WILL REMAIN
OVER THE WATERS. THE CHC OF SHOWERS WILL INCREASE FROM ABOUT 20
PERCENT EARLY THIS EVENING TO ABOUT 40 PERCENT BY DAWN ON
THURSDAY. SHOWERS MAY BE ACCOMPANIED BY TSTMS. SHOWERS ARE LIKELY
(60 TO 70 PERCENT CHC) THROUGHOUT THE DAY ON THURSDAY AS THE
MAXIMUM MOISTURE AND INSTABILITY AND MOISTURE PASSES OVER THE
AREA. ALMOST ALL AREAS CAN EXPECT RAIN AT SOME POINT DURING THE
DAY. MOST PEOPLE WILL AT LEAST HEAR THUNDER, IF NOT EXPERIENCE A
TSTM AS WELL. THIS WILL NOT BE A CONTINUOUS RAIN EVENT BUT RATHER
A DAY WITH PERIODS OF SHOWERS/TSTMS AND PERIODS OF MUGGY WEATHER
WITH NO RAIN. THE CHC OF SHOWERS/TSTMS WILL THEN SLOWLY DIMINISH
FROM THURSDAY EVENING THROUGH EARLY FRIDAY EVENING WHEN THE THREAT
OF SHOWERS SHOULD END.
RAINFALL AMOUNTS WILL BE THE HARDEST PART OF THIS FORECAST.
AMOUNTS WILL BE HIGHLY VARIABLE DUE TO THE SHOWERY NATURE OF THIS
SYSTEM. THE CURRENT FORECAST CALLS FOR MOST OF LA AND VTA COUNTIES
TO RECEIVE A HALF INCH OF RAIN WITH LOCAL THREE QUARTER INCH
AMOUNTS. SOME MTN AREAS COULD SEE UPWARDS OF AN INCH. AREAS NORTH
OF POINT CONCEPTION ARE FORECAST TO GET ABOUT HALF THESE AMOUNTS,
BUT IF THE MAIN MOISTURE AXIS TRACKS A LITTLE TO THE WEST MORE
RAIN WILL FALL. THESE NUMBERS ARE GENERAL NUMBERS AND THERE WILL
VERY LIKELY BE OUTLIERS SOME AREA MAY ONLY SEE A TENTH OF AN INCH
BUT OTHER AREAS COULD SEE UP TO 2 INCHES OF RAIN IF A STRONG
SHOWER OR TSTM MOVES OVER THE AREA. RAINFALL RATES UNDER THE
HEAVIER CELLS WILL BE NEAR A HALF INCH PER HOUR, BUT WITH PWATS
APPROACHING 2 INCHES CANNOT RULE OUT THE POSSIBILITY OF 1 INCH
PER HOUR RATES.
A FLOOD WATCH WILL BE CONSIDERED THIS MORNING AFTER CONSULTING THE
12Z MDLS AND COORDINATING WITH SURROUNDING OFFICES.
THE INCREASING CLOUDS WILL KNOCK A FEW DEGREES OFF OF MOST TEMPS
TODAY (THE CENTRAL COAST WILL ACTUALLY WARM UP SOME WITH SOME
OFFSHORE FLOW FROM THE EAST). THE INCREASE IN HUMIDITY WILL,
HOWEVER, NEGATE ANY AFFECTS OF THE TEMPERATURE DECREASE. THE
MASSIVE AMOUNT OF CLOUDS AND PERIODS OF RAIN ON THURSDAY WILL
BRING 5 TO 10 LOCALLY 15 DEGREES OF COOLING TO AREAS AWAY FROM THE
COAST DROPPING ALMOST ALL TEMPS INTO THE 80S. STILL WITH THE
HUMIDITY IT WILL FEEL VERY STICKY AND TROPICAL. NOT MUCH CHANGE
IN TEMPS ON FRIDAY IT WILL STILL BE HUMID BUT NOT QUITE AS MUCH AS
ON THURSDAY.
LONG TERM (SAT-TUE)
17/1231 AM.
THE WEEKEND SHOULD BE DRY BUT THERE IS A SLIGHT CHC (20 PERCENT)
OF SOME AFTERNOON CONVECTION OVER THE TALLER PEAKS OF THE VTA AND
LA MTNS. THE ATMOSPHERE WILL SLOWLY DRY BUT BOTH DAYS WILL FEEL
PRETTY MUGGY WITH HIGHER THAN NORMAL HUMIDITIES. AN UPPER HIGH
WILL PUSH INTO SRN CA FROM THE SOUTH AND HGTS WILL RISE TO 588
DAM. LOOK FOR TWO DAYS WITH 2 TO 4 DEGREES OF WARMING, WHICH WILL
BRING MAX TEMPS UP TO NEAR NORMAL BY SUNDAY.
THERE IS QUITE A BIT OF UNCERTAINTY WITH THE FORECAST FOR EARLY
NEXT WEEK. THE EC AND MOST OF ITS ENSEMBLES FAVOR A VERY WARM
PATTERN WITH A STRONG UPPER RIDGE OVER THE AREA - THIS SOLUTION
WOULD BRING TRIPLE DIGIT TEMPS BACK TO THE VLYS. THE GFS IS COOLER
WITH A LITTLE TROFFIER PATTERN. THERE DOES SEEM TO BE PRETTY GOOD
CONSENSUS THAT THERE WILL BE SOME WARMING ON MONDAY.
TUESDAY'S FORECAST FAVORS A TROFFIER COOLER PATTERN WITH A LITTLE
MORE MARINE LAYER.
AVIATION
17/1657Z.
AT 1630Z AT KLAX, THE MARINE LAYER DEPTH WAS AROUND 500 FEET.
THE TOP OF THE INVERSION WAS 2500 FEET WITH A TEMPERATURE OF
26 DEGREES CELSIUS.
OVERALL, MODERATE CONFIDENCE IN 18Z TAF PACKAGE. WITH SURGE OF
SUBTROPICAL MOISTURE THROUGH THE PERIOD, GENERAL VFR CONDITIONS
ARE EXPECTED AT ALL SITES. THERE WILL BE THE POTENTIAL FOR
WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS AT ALL SITES
THROUGH THE PERIOD. THIS SHOWER/THUNDERSTORM ACTIVITY COULD
PRODUCE BRIEF PERIOD OF IFR TO MVFR CIG/VSBY RESTRICTIONS.
KLAX...MODERATE CONFIDENCE IN 18Z TAF. THERE IS A 20% CHANCE OF
THUNDERSTORMS AFTER 00Z WHICH COULD BRING BRIEF PERIODS OF IFR TO
MVFR CONDITIONS. THERE IS A 20% CHANCE OF EASTERLY WINDS AROUND 7
KNOTS AFTER 06Z.
KBUR...MODERATE CONFIDENCE IN 18Z TAF. THERE IS A 20% CHANCE OF
THUNDERSTORMS AFTER 00Z WHICH COULD BRING BRIEF PERIODS OF IFR TO
MVFR CONDITIONS.
MARINE
17/730 AM.
FOR THE OUTER WATERS, MODERATE TO HIGH CONFIDENCE IN CURRENT
FORECAST. THERE IS A 40-60% CHANCE OF SMALL CRAFT ADVISORY (SCA)
LEVEL WINDS THIS AFTERNOON AND EVENING ACROSS PZZ673/676. FOR
THURSDAY AND FRIDAY, HIGH CONFIDENCE IN WINDS AND SEAS REMAINING
BELOW SCA LEVELS. FOR SATURDAY AND SUNDAY, THERE IS A 50-70%
CHANCE OF SCA LEVEL WINDS ACROSS ALL OF THE OUTER WATERS.
FOR THE INNER WATERS NORTH OF POINT SAL, MODERATE TO HIGH
CONFIDENCE IN CURRENT FORECAST. TODAY THROUGH SATURDAY, HIGH
CONFIDENCE IN WINDS AND SEAS REMAINING BELOW SCA LEVELS. FOR
SUNDAY, THERE IS A 40% CHANCE OF SCA LEVEL WINDS IN THE AFTERNOON
AND EVENING HOURS.
FOR THE INNER WATERS SOUTH OF POINT CONCEPTION, MODERATE TO HIGH
CONFIDENCE IN CURRENT FORECAST. THERE IS A 50-60% CHANCE OF SCA
LEVEL WINDS ACROSS WESTERN SECTIONS THIS AFTERNOON AND EVENING.
FOR THURSDAY AND FRIDAY, HIGH CONFIDENCE IN WINDS AND SEAS
REMAINING BELOW SCA LEVELS. FOR SATURDAY AND SUNDAY, THERE IS A
40-50% CHANCE OF SCA LEVEL WINDS ACROSS THE WESTERN HALF OF THE
SANTA BARBARA CHANNEL WITH HIGH CONFIDENCE IN WINDS AND SEAS
REMAINING BELOW SCA LEVELS ELSEWHERE.
THE REMNANTS OF FORMER TROPICAL STORM MARIO WILL AFFECT THE
SOUTHERN CALIFORNIA COASTAL WATERS THROUGH FRIDAY. SHOWERS AND
SCATTERED THUNDERSTORMS CAN BE EXPECTED THROUGH FRIDAY WITH THE
HIGHEST CHANCES OF IMPACTS TONIGHT THROUGH THURSDAY NIGHT. ANY
THUNDERSTORMS THAT DEVELOP WILL BE CAPABLE OF GUSTY AND ERRATIC
WINDS, LOCALLY ROUGH SEAS, FREQUENT AND DANGEROUS LIGHTNING AND
BRIEF HEAVY RAIN. ADDITIONALLY, WATERSPOUTS CANNOT BE RULED OUT
ENTIRELY. PLEASE MONITOR THE FORECAST IF YOU HAVE ANY PLANS ON
GOING OUT ON THE WATER THIS WEEK.
LOX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT FROM 2 PM THIS AFTERNOON TO 9
PM PDT THIS EVENING FOR ZONES 650-655-673-676. (SEE LAXMWWLOX).
PUBLIC...MW/RORKE
AVIATION...RAT
MARINE...RAT
SYNOPSIS...MW
WEATHER.GOV/LOSANGELES
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