410
FXUS66 KLOX 211004
AFDLOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
304 AM PDT TUE OCT 21 2025
SYNOPSIS
21/258 AM.
LOW CLOUDS AND FOG WILL AFFECT SOME COASTAL AREAS (MOSTLY ACROSS
THE CENTRAL COAST) TODAY AND TUESDAY. THEN, A DEEPENING MARINE
LAYER WILL BRING LOW CLOUDS AND SOME DRIZZLE TO ALL OF THE COASTS
AND VALLEYS ON WEDNESDAY. MAX TEMPERATURES ON WEDNESDAY WILL FALL
DRAMATICALLY WITH HIGHS ONLY IN THE MID 60S TO LOWER 70S ACROSS
ALL OF THE COASTS AND VLYS. DRY AND WARMER CONDITIONS ARE SLATED
FOR THE END OF THE WEEK.
SHORT TERM (TDY-THU)
21/258 AM.
A 568 DAM UPPER LOW THAT HAS BEEN SPINNING TO THE SW WILL BEGIN TO
MOVE TO THE NE TODAY. IT WILL ACTUALLY NOT HAVE THAT MUCH AFFECT
ON THE WEATHER OTHER THAN A SLIGHT INCREASE IN MARINE LAYER
CLOUDS. IT WILL LOWER HGTS SLIGHTLY AND INCREASE THE ONSHORE FLOW.
THE INCREASE IN ONSHORE FLOW WILL COOL THE CSTS AND VLYS BY 3 TO 6
DEGREES.
THE LOW WILL CONTINUE TO MOVE TO THE NE OVERNIGHT AND WILL END UP
JUST OFF OF PT CONCEPTION JUST BEFORE DAWN WEDNESDAY. THE LIFT AND
LOWERING HGTS ASSOC WITH THE LOW'S PROGRESSION WILL QUICKLY DEEPEN
THE MARINE LAYER TO OVER 5000 FT. THIS WILL PRODUCE AN EXTENSIVE
BATCH OF STRATUS THAT WILL COVER THE CSTS AND VLYS AND XTND TO THE
CSTL SLOPE. THIS RAPID DEEPENING IS A LIKELY RECIPE FOR DRIZZLE OR
EVEN LIGHT RAIN NEAR THE FOOTHILLS. RAIN ACTUALLY ASSOC WITH LOW
MAY FALL ACROSS THE NW CORNER OF SLO COUNTY. THE COOL AIR FROM THE
UPPER LOW WILL WEAKEN THE MARINE INVERSION AS IT PASSES OVERHEAD
WEDNESDAY AND THIS WILL ALLOW FOR GOOD CLEARING. THE UPPER LOW
DOES PASS OVER THE MTNS IN THE AFTERNOON SO THE CHC OF MTN
CONVECTION IS NOT ZERO. THAT SAID, ALL HI REZ CONVECTIVE ALLOWING
MDLS DO NOT SHOW ANYTHING DEVELOPING. SO WILL KEEP CONVECTION OUT
OF THE FORECAST BUT WILL GIVE A TIP OF THE HAT TO THE POSSIBILITY
BY BRINGING AFTERNOON CLOUDS TO THE MTNS. THE MARINE LAYER,
ONSHORE FLOW AND LOWERING HGTS WILL ALL TEAM UP TO LOWER TEMPS 2
TO 4 DEGREES ACROSS THE CSTS AND AN IMPRESSIVE 8 TO 12 DEGREES
ACROSS THE VLYS MTNS AND INTERIOR. MAX TEMPS ACROSS THE CSTS/VLYS
WILL ONLY BE IN THE UPPER 60S TO MID 70S OR 5 TO 10 DEGREES BLO
NORMAL.
GUSTY NORTH WINDS WILL DEVELOP WEDNESDAY NIGHT BUT WILL LIKELY NOT
REACH ADVISORY LEVELS.
A RIDGE WILL BUILD INTO THE AREA ON THURSDAY. HGTS WILL REBOUND TO
580 DAM. THERE WILL BE OFFSHORE FLOW FROM THE NORTH AND ONLY WEAK
ONSHORE FLOW TO THE EAST. THE COLD AIR FORM THE PREVIOUS DAY'S LOW
ELIMINATED THE MARINE INVERSION THERE WILL LIKELY BE NO LOW CLOUDS
ONLY SUNNY SKIES. MAX TEMPS WILL WARM 4 TO 8 DEGREES BUT WILL
STILL REMAIN BLO NORMAL.
LONG TERM (FRI-MON)
21/258 AM.
NOT MUCH WILL BE GOING ON WEATHER-WISE ON FRIDAY. WEAK RIDGING
WITH 582 DAM HGTS WILL BE OVERHEAD AND THERE WILL BE WEAK OFFSHORE
FLOW FROM THE NORTH AND WEAK ONSHORE FLOW TO THE EAST. IT LOOKS
LIKE THERE WILL NOT MUCH OF ANY MARINE LAYER CLOUDS AND IT WILL BE
A MOSTLY SUNNY DAY. MAX TEMPS WILL WARM 2 TO 4 DEGREES AND WILL
COME IN A FEW DEGREES EITHER SIDE OF NORMAL.
A BROAD TROF ASSOC WITH AN UPPER LOW IN THE GULF OF ALASKA WILL
SWEEP OVER THE STATE ON SATURDAY. IT WILL ENERGIZE THE MARINE
LAYER AND LOW CLOUDS SHOULD COVER THE CSTS AND LOWER VLYS IN THE
MORNING WITH MID AND HIGH CLOUDS CREATING PARTLY TO MOSTLY CLOUDY
SKIES IN THE AFTERNOON. FALLING HGTS, INCREASED ONSHORE FLOW AND
EXTRA CLOUDS WILL ALL COMBINE TO KNOCK 2 TO 4 DEGREES OFF OF THE
AFTERNOON HIGHS.
THERE IS A SMALL CHANCE THAT A WEAK IMPULSE EMBEDDED IN THE TROF WILL
BRING SOME RAIN TO SLO COUNTY SATURDAY EVENING AND EARLY SUNDAY
MORNING. MORE THAN LIKELY, HOWEVER, IT WILL JUST BRING EXTRA MID
AND HIGH LEVEL CLOUDS ON TOP OF A FAIRLY EXTENSIVE LOW CLOUD
LAYER. SKIES WILL BE PARTLY TO MOSTLY CLOUDY. THE COOL AIR USHERED
BY THE LOW WILL COOL THE INTERIOR BY 6 TO 8 DEGREES. A MINIMAL
INCREASE IN ONSHORE FLOW WILL COOL THE CSTS/VLYS BY 1 OR 2
DEGREES.
DECENT NORTHERLY FLOW WILL DEVELOP ON MONDAY IN THE WAKE OF THE
TROF WITH A SMALL RIDGE BUILDING IN FROM THE WEST AS WELL. THE
OFFSHORE FLOW SHOULD KEEP THE LOW CLOUDS AWAY. THE OFFSHORE FLOW
AND THE INCREASE HGTS FROM THE RIDGE WILL LEAD TO 2 TO 3 DEGREES
OF WARMING.
BEYOND THE 7 DAY FORECAST THERE ARE SEVERAL INTERESTING OPTIONS
FOR THE TUE/WED TIME FRAME. A MDT SANTA ANA IS STILL POSSIBLE BUT
LOOKS LESS LIKELY AT THIS TIME. THERE WAS GOOD MDL AGREEMENT
EARLIER ABOUT A VERY WARM UPPER HIGH AND WHILE THE EC STILL THINKS
THIS WILL HAPPEN THE GFS IS NOW NOT IN AGREEMENT WITH A COOLER
PATTERN FCST.
AVIATION
21/0527Z.
AT 0459Z AT KLAX, THERE WAS A SURFACE INVERSION TO 1500 FEET WITH
A TEMPERATURE OF 24 DEGREES C.
HIGH CONFIDENCE IN TAFS FOR KPRB, KBUR, KVNY, KPMD, AND KWJF.
MODERATE CONFIDENCE IN TAFS FOR KSMX AND KSBP. CLEARING TIMES MAY
BE OFF +/- 1 HOUR.
LOW CONFIDENCE IN REMAINING TAFS. THERE IS A 40% CHANCE FOR LIFR
TO IFR CONDS, WITH LOCALIZED VLIFR VSBYS, AT KOXR, KCMA, KLAX,
KSMO, AND KLGB THROUGH 18Z, BUT ESPECIALLY FROM 12Z-17Z.
FOR ALL COASTAL AND COASTAL VALLEY SITES, LOWER CONFIDENCE AFTER
00Z WED DUE TO UNCERTAINTY OF CIG HEIGHT (+/-500 FEET) AND TIMING
(+/- 3 HOURS) AS A CUTOFF LOW WORKS ITS WAY INTO SOUTHERN
CALIFORNIA, WHICH SHOULD PROVIDE SIGNIFICANT LIFT TO THE MARINE
LAYER.
KLAX...LOW CONFIDENCE IN TAF. 40% CHANCE FOR VSBYS 1SM-5SM AND
OVC002-008 CIGS 10Z-18Z. AFTER 00Z WED, HIGH CONFIDENCE IN RETURN
OF LOW CLOUDS, BUT LOW CONFIDENCE IN CIG HEIGHTS (+/- 500 FEET)
AND TIMING (+/- 3 HOURS). NO SIGNIFICANT EAST WIND COMPONENT
EXPECTED.
KBUR...HIGH CONFIDENCE IN TAF.
MARINE
21/220 AM.
DENSE FOG WILL CONTINUE ACROSS PORTIONS OF THE COASTAL WATERS
THROUGH LATE THIS MORNING.
A LONG PERIOD NORTHWEST SWELL WILL CONTINUE TO BRING 10-14 FOOT
SEAS TO THE OUTER WATERS AND NEARSHORE WATERS ALONG THE CENTRAL
COAST INTO EARLY NEXT WEEK, BUT A RELATIVE LULL IS LIKELY LATE
WEDNESDAY INTO THURSDAY BEFORE ANOTHER LONG PERIOD SWELL ARRIVES,
INCREASING SEAS TO 12-14 FEET INTO EARLY NEXT WEEK. OBSERVED WAVE
HEIGHTS HAVE BEEN WELL OVER MODEL GUIDANCE, THUS THE SMALL CRAFT
ADVISORY (SCA) HAS BEEN EXTENDED THROUGH LATE WEDNESDAY WHEN THERE
IS A NOTICEABLE GAP BETWEEN SWELLS.
NORTHWEST WINDS WILL INCREASE TO 20-30 KNOTS WEDNESDAY ACROSS THE
WATERS SOUTH OF POINT CONCEPTION, INCLUDING THE SANTA BARBARA
CHANNEL AND INNER WATERS ADJACENT TO LOS ANGELES AND ORANGE
COUNTIES. CHOPPY, SHORT PERIOD WIND WAVES WILL OCCUR ACROSS THE
SOUTHERN CALIFORNIA BIGHT WEDNESDAY AFTERNOON THROUGH THE LATE
NIGHT HOURS.
WINDS WILL DECREASE OVER THE INNER WATERS SOUTH OF POINT
CONCEPTION OVERNIGHT BUT WILL EXPAND TO THE REMAINDER OF THE
OUTER WATERS AND POTENTIALLY THE NEARSHORE WATERS ADJACENT TO THE
CENTRAL COAST THURSDAY THROUGH AT LEAST FRIDAY.
LOX WATCHES/WARNINGS/ADVISORIES
CA...DENSE FOG ADVISORY IN EFFECT UNTIL 9 AM PDT THIS MORNING FOR
ZONES 340-341-346-347. (SEE LAXNPWLOX).
HIGH SURF ADVISORY IN EFFECT UNTIL 3 AM PDT THURSDAY FOR
ZONES 340-346. (SEE LAXCFWLOX).
PZ...SMALL CRAFT ADVISORY IN EFFECT UNTIL 3 PM PDT THIS AFTERNOON
FOR ZONE 645. (SEE LAXMWWLOX).
SMALL CRAFT ADVISORY IN EFFECT UNTIL 3 AM PDT THURSDAY FOR
ZONES 670-673-676. (SEE LAXMWWLOX).
PUBLIC...RORKE
AVIATION...LEWIS
MARINE...LEWIS
SYNOPSIS...CILIBERTI
WEATHER.GOV/LOSANGELES
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