139
FXUS66 KLOX 170350
AFDLOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
850 PM PDT TUE SEP 16 2025
SYNOPSIS
16/146 PM.
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 (TUE-FRI)
16/850 PM.
***UPDATE***
SATELLITE IMAGERY TONIGHT SHOWS CONTINUOUS MARINE LAYER CLOUDS
HAVE DEVELOPED NORTH OF POINT CONCEPTION AND ARE BEGINNING TO
PUSH ON SHORE. ALSO STARTING TO SEE THE VERY BEGINNING OF A
SMATTERING CLOUDS FILTERING IN FROM THE SOUTH, CYCLING AROUND
TROPICAL STORM MARIO. THE CLOUD AND FOG FORECAST FOR WILL BE
SOMEWHAT TRICKY FOR LA COUNTY, AS UPPER LEVEL CLOUDS COULD START
TO DISRUPT THE MARINE LAYER. LOOKING INTO WEDNESDAY, STILL SEEING
A LARGE AMOUNT OF VARIABILITY BETWEEN GUIDANCE IN TERMS OF RAIN
AND THUNDERSTORM CHANCES ALONG WITH AMOUNTS. WE COULD BEGIN TO SEE
SOME ISOLATED SHOWERS AS EARLY AS WEDNESDAY MORNING OVER VENTURA
AND LA COUNTIES, SPREADING INTO SANTA BARBARA COUNTY THROUGH THE
AFTERNOON. CURRENTLY, THE BEST TIME FOR MORE WIDESPREAD RAIN LOOKS
LIKE WEDNESDAY NIGHT INTO EARLY THURSDAY ASSOCIATED WITH
VORTICITY ADVECTION ROTATING THROUGH FROM THE SOUTH ALONG WITH A
REMNANT RAIN BAND FROM THE TROPICAL SYSTEM. SHOWERS MAY BE MORE
SCATTERED TO ISOLATED IN NATURE LATER THURSDAY, BUT WILL NEED TO
CONTINUE WATCHING FUTURE HIGH RESOLUTION SOLUTIONS FOR
CONSISTENCY. PWAT VALUES INCREASE SIGNIFICANTLY ON THURSDAY
THROUGHOUT THE FORECASTING AREA TO AN IMPRESSIVE 1.7 TO 2 INCHES,
SO ANY THUNDERSTORMS THAT FORM IN THIS ENVIRONMENT WILL HAVE THE
POTENTIAL TO TAP INTO TROPICAL LEVELS OF MOISTURE.
***FROM PREVIOUS DISCUSSION***
MOISTURE FROM WHAT WAS TROPICAL STORM MARIO IS RAPIDLY MOVING UP
THE BAJA COAST AND WILL BE ENTERING US WATERS OVERNIGHT TONIGHT.
IT'S BEEN AN ACTIVE DAY OF THUNDERSTORMS ACROSS THE SPINE OF
NORTHERN BAJA BUT SO FAR NO CONVECTION ON THIS SIDE OF THE BORDER.
WHILE THERE STILL REMAINS A LOT OF UNCERTAINTIES, CONFIDENCE IS
GROWING THAT MOST AREAS ACROSS THE 4 COUNTY AREA WILL GET AT LEAST
SOME RAIN BETWEEN WEDNESDAY AFTERNOON AND THURSDAY. AMOUNTS ARE
GOING TO BE HIGHLY VARIABLE, WITH SOME AREAS POSSIBLY JUST GETTING
AROUND A TENTH OF AN INCH, AND OTHER AREAS (POSSIBLY NOT THAT FAR
AWAY) AS MUCH AS 1-2 INCHES. AS OF NOW THE HIGHER RAIN AMOUNTS
ARE EXPECTED IN THE MOUNTAINS SOUTH OF PT CONCEPTION, BUT IF
MARIO'S TRACK REVERTS BACK TO ITS FARTHER WEST SOLUTION THEN
HEAVIER AMOUNTS COULD REACH THE CENTRAL COAST. THERE ARE ALSO SOME
SIGNALS IN THE MODELS INDICATING THE POTENTIAL FOR SEVERE
WEATHER, INCLUDING AN ISOLATED SMALL TORNADO. THE BEST CHANCE FOR
ANY LIGHTNING WOULD LIKELY BE AS THE MOISTURE IS JUST ARRIVING
WEDNESDAY NIGHT INTO EARLY THURSDAY, AFTER WHICH THE ENVIRONMENT
MAY BE TOO MOIST WITH WITH TOO MUCH CLOUD COVER TO SUPPORT THUNDER
DEVELOPMENT. RAIN RATES UP TO AT LEAST A HALF INCH ARE POSSIBLE
WITH THE HEAVIER CELLS, AND CAN'T RULE OUT RATES AS HIGH AS AN
INCH PER HOUR GIVEN THE 2+" OF PRECIPITABLE WATER.
NEEDLESS TO SAY IT WILL BECOME INCREASINGLY MUGGY LATER WEDNESDAY
INTO THURSDAY. TEMPERATURES ARE EXPECTED TO COOL A FEW DEGREES IN
MOST AREAS WEDNESDAY AND SEVERAL MORE DEGREES THURSDAY WITH
INCREASING CLOUD COVER AND SHOWERS. OVERNIGHT LOWS WILL BE MUCH
WARMER THAN NORMAL AS WELL AS THE MOISTURE ALOFT WILL TRAP A LOT
OF THE HEAT FROM THE DAYTIME.
PRECIP CHANCES WILL DECREASE LATER THURSDAY NIGHT INTO FRIDAY
MORNING AND SHOULD BE COMPLETELY GONE BY FRIDAY AFTERNOON.
TEMPERATURES WILL STILL BE 5-10 DEGREES BELOW NORMAL, BUT WITH
STILL MUCH HIGHER THAN NORMAL HUMIDITY IT WILL FEEL MUCH WARMER.
LONG TERM (SAT-TUE)
16/231 PM.
THE WEEKEND FORECAST HAS BECOME LESS CERTAIN AS THERE ARE SOME
MODELS NOW BRINGING UP SOME ADDITIONAL MOISTURE AND INSTABILITY
THAT COULD TRIGGER ISOLATED SHOWERS. THIS MAY END UP JUST BEING
OVER THE MOUNTAINS BUT IF THERE'S ANY LEFT OVER INSTABILITY AFTER
MARIO DEPARTS IT MAY NOT TAKE MUCH TO TRIGGER AN BRIEF SHOWER. THE
MOST LIKELY OUTCOME IS A DRY WEEKEND WITH TEMPERATURES WARMING
BACK TO NORMAL LEVELS AND STILL WITH ELEVATED HUMIDITY LEVELS.
NEXT WEEK IS ALSO UNCERTAIN AS ANOTHER TROPICAL WAVE OVER MEXICO
MOVES OUT OVER THE PACIFIC. THE UPPER LEVEL PATTERN MAY BE
FAVORABLE TO GET SOME OF THAT MOISTURE INTO THE AREA EARLY NEXT
WEEK BUT WILL HAVE TO SEE HOW THE PATTERN EVOLVES THE NEXT FEW
DAYS. THERE ALSO SOME MODEL SOLUTIONS INDICATING A STRONG HIGH
PRESSURE SYSTEM DEVELOPING OVER SOUTHERN CALIFORNIA WITH THE
POTENTIAL FOR TRIPLE DIGIT HEAT TO RETURN TO THE VALLEYS.
AVIATION
17/0045Z.
AT 0015Z AT KLAX, THE MARINE INVERSION WAS AROUND 600 FEET DEEP.
THE TOP OF THE INVERSION WAS 2800 FEET WITH A TEMPERATURE OF 27
DEGREES CELSIUS.
HIGH CONFIDENCE IN VALLEY AND DESERT TAFS AS VFR CONDITIONS ARE
EXPECTED THROUGH THE PERIOD. 20% CHANCE OF -SHRA POSSIBLE AT KPMD
AND KWJF THROUGH 06Z, AND AFTER 20Z.
FOR COASTAL TAFS, LOW TO MODERATE CONFIDENCE IN TAFS. LOW
CONFIDENCE IN TAFS FOR KSBP. THERE IS A 40% CHANCE LOW CLOUDS TO
NOT MAKE IT TO KSBP TONIGHT. FOR KSMX AND KSBP, 50% CHANCE FOR
VLIFR CONDS AT ANY POINT WHILE CIGS ARE PRESENT. FOR SITES SOUTH
OF POINT CONCEPTION, THERE IS A 20-30% CHANCE FOR LIFR TO IFR
CONDS. THERE IS A 20% CHANCE FOR -SHRA AND -TSRA AFTER 20Z.
CHANCES INCREASE AFTER 00Z THU.
KLAX...MODERATE CONFIDENCE IN TAF. HIGH CONFIDENCE IN VFR
CONDITIONS THROUGH THIS EVENING. FOR TONIGHT, THERE IS A 30%
CHANCE OF CIGS BETWEEN 004-010 FROM 08Z-17Z. 20% CHANCE OF -SHRA
AFTER 20Z, THEN A 30% CHANCE 00Z-06Z. NO SIGNIFICANT EAST WIND
COMPONENT IS EXPECTED.
KBUR...HIGH CONFIDENCE IN TAF. 20% CHANCE FOR -SHRA AFTER 20Z.
MARINE
16/840 PM.
EARLY WEDNESDAY MORNING THROUGH FRIDAY, THE REMNANTS OF TROPICAL
STORM MARIO WILL IMPACT THE SOUTHERN CALIFORNIA COASTAL WATERS.
PERIODS OF SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS THE WATERS.
ANY THUNDERSTORMS THAT DEVELOP WILL BE CAPABLE OF FREQUENT
LIGHTNING AS WELL AS STRONG AND ERRATIC WINDS. PLEASE MONITOR THE
FORECAST IF YOU HAVE ANY PLANS ON GOING OUT ON THE WATER THIS
WEEK.
LOW CONFIDENCE IN FORECAST FOR WINDS AND SEAS WEDNESDAY AFTERNOON
THROUGH THURSDAY NIGHT AS MODELS HAVE LITTLE CONSENSUS ON
INTENSITY AND DIRECTION OF WINDS AS THE REMNANT LOW FROM TROPICAL
STORM MARIO MOVES INTO THE REGION. LOWEST CONFIDENCE FOR THE
COASTAL WATERS SOUTH OF POINT CONCEPTION, FROM NEARSHORE TO 60 NM
BEYOND THE COAST. SUDDEN WIND SHIFTS IN DIRECTION AND SPEEDS WILL
BE COMMON, AND SEAS WILL LIKELY BE CHOPPY.
FRIDAY THROUGH SUNDAY, MODERATE CONFIDENCE IN WINDS REMAINING
BELOW SMALL CRAFT ADVISORY (SCA) LEVELS. THERE IS A 30% CHANCE FOR
SCA WINDS IN TYPICAL WINDY SPOTS FROM POINT CONCEPTION SATURDAY
AND SUNDAY AFTERNOON AND EVENING.
LOX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...PHILLIPS/MW
AVIATION...LEWIS
MARINE...LEWIS
SYNOPSIS...MW
WEATHER.GOV/LOSANGELES
EXPERIMENTAL GRAPHICAL HAZARDOUS WEATHER OUTLOOK AT:
HTTPS://WWW.WEATHER.GOV/ERH/GHWO?WFO=LOX
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