Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 070257
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
800 PM PDT MON JUL 6 2015

.SYNOPSIS...

A LOW PRESSURE SYSTEM CURRENTLY OFF THE WEST COAST WILL SLOWLY MOVE
TOWARD THE AREA...THEN INLAND...THROUGH THE WEEK. THIS WILL KEEP
AFTERNOON TEMPERATURES A FEW DEGREES BELOW NORMAL AND CONTINUE THE
TYPICAL NIGHT THROUGH MORNING LOW CLOUDS AND FOG PATTERN WEST OF THE
MOUNTAINS. ON THURSDAY AND FRIDAY...AS THE LOW MOVES INLAND...THERE
WILL BE THE SLIGHT POSSIBILITY OF AN ISOLATED SHOWER OR THUNDERSTORM
OVER THE MOUNTAINS IN THE AFTERNOON AND EVENING HOURS.

&&

.UPDATE...OVERALL...VERY QUIET EVENING ACROSS THE FORECAST DISTRICT.
LATEST AMDAR SOUNDINGS INDICATE MARINE INVERSION BASED AROUND 2000
FEET DEEP THIS EVENING...WITH SATELLITE/SURFACE OBS ONLY INDICATING
SOME VERY PATCHY STRATUS ALONG THE IMMEDIATE CENTRAL COAST AND
ACROSS PARTS OF THE LOS ANGELES COUNTY COAST. OVERNIGHT...WITH
CONTINUED ONSHORE FLOW WILL EXPECT STRATUS COVERAGE TO EXPAND ACROSS
THE COASTAL PLAIN AND SPREAD INTO THE COASTAL VALLEYS. HOWEVER
CONFIDENCE IN EXACTLY HOW WIDESPREAD THE COVERAGE WILL BE IS ONLY
MODERATE AT BEST. THERE IS A DECENT CHANCE THAT STRATUS COVERAGE
WILL REMAIN PATCHY ACROSS THE CENTRAL COAST AS WELL AS ACROSS
VENTURA COUNTY. WITH A LITTLE NORTHERLY OFFSHORE PUSH...THE SOUTH
COAST OF SANTA BARBARA SHOULD REMAIN CLEAR OVERNIGHT.

FOR THE EVENING...THE SKY COVERAGE FOR THIS EVENING WAS TWEAKED TO
BETTER REFLECT CURRENT SITUATION. FOR THE OVERNIGHT HOURS...THE
FORECAST WAS LEFT AS IS...BUT WOULD NOT BE SURPRISED TO SEE THE
STRATUS COVERAGE TRIMMED BACK FOR TUESDAY MORNING. OTHERWISE...THE
FORECAST IN THE IMMEDIATE SHORT TERM LOOKED GOOD.

***FROM PREVIOUS DISCUSSION***

.SHORT TERM (TODAY-THU)...AFTERNOON TEMPERATURES WILL BE QUITE
SIMILAR TO YESTERDAY AS MOST OF THE COAST ANY VALLEY AREAS REMAIN
UNDER THE STRONG INFLUENCE OF THE MARINE LAYER AND STRONG ONSHORE
FLOW...THE EXCEPTION MAY BE IN THE MOUNTAIN AREAS WHICH ARE RUNNING
A DEGREE OR SO COOLER.  COASTAL STRATUS IS STILL PRESENT FROM LA
COUNTY THROUGH SANTA BARBARA.

THE WIND IS BEGINNING TO BLOW IN THE ANTELOPE VALLEY WITH TWO
REPORTS OF 25 MPH GUSTS SO FAR.  EXPECTING OFFSHORE EVENING WINDS IN
WESTERN SANTA BARBARA COUNTY TO HELP KEEP THE STRATUS OFF OF THE SBA
COUNTY SOUTH COAST TONIGHT.

TUESDAY AND WEDNESDAY WILL BE VERY SIMILAR TO TODAY WHILE COOLING A
DEGREE OR SO EACH DAY.  THE DEEP MARINE LAYER AND ONSHORE FLOW WILL
DRIVE THE FORECAST FOR THE COASTS AND COASTAL VALLEYS.  SYNOPTICALLY
THERE IS AN UPPER LOW ABOUT 450 MILES WEST OF SAN FRANCISCO AND A
WEAK RIDGE OVER AZ/NV.  THE LOW WILL SLOWLY MOVE EAST AND BE OVER
MONTEREY BY MID-MORNING WEDNESDAY. MONTEREY AND HANFORD HAVE
INTRODUCED PRECIP POSSIBILITIES FOR THEIR AREAS ON WEDNESDAY...BUT
NOT SEEING ENOUGH FORCING OR MOISTURE FOR OUR AREA AT THIS TIME.

AS THE LOW PASSES TO OUR NORTH ON THURSDAY IT COULD BRING ENOUGH
LIFT TO RAISE THE LOW CLOUDS UP THE COASTAL SLOPES AND FORCE SOME
DRIZZLE.  LATER IN THE DAY A 100 MPH JET STREAK WILL PASS DIRECTLY
OVER OUR AREA AND THERE ARE MECHANICS FOR LIFT WHICH INTRODUCE THE
POSSIBILITY OF SOME AFTERNOON STORMS...NOT SEEING VERY MUCH MOISTURE
AT THIS TIME...BUT ENOUGH TO INTRODUCE A SLIGHT CHANCE OF AFTERNOON
CONVECTION INTO THE FORECAST... PRIMARILY OVER THE VENTURA COUNTY
MOUNTAINS.

.LONG TERM (FRI-MON)...

THERE WILL BE AN UPPER TROF TO OUR SOUTHWEST EVEN AFTER THE LOW
PASSES BY AND IT WILL KEEP THE ONSHORE PUSH GOING WITH CONTINUED
COASTAL STRATUS THROUGH THE WEEKEND.  THE EUROPEAN AND GFS MODELS
BEGIN TO DIVERGE IN THE LONG TERM. THE GFS SOLUTION IS FOR A RETURN
TO THE OFFSHORE LOW AND SW/NE ELONGATED FOUR CORNERS HIGH THAT COULD
START MOVING MONSOON MOISTURE BACK TO THE AREA BY LATE MONDAY.  THE
EUROPEAN SPINS AN UPPER LOW FROM THE GULF OF ALASKA DOWN TO THE
CA/OR BORDER AND HAS THE RIDGE ORIENTED MORE NORTH/SOUTH WHICH KEEPS
THE MONSOON MOISTURE TO OUR EAST.  FAVORING THE GFS AT THIS TIME AS
IT HAS BEEN THE BETTER MODEL SO FAR THIS SUMMER.

&&

.AVIATION...06/2335Z...

AT 2302Z...THE MARINE INVERSION AT KLAX WAS BASED AT 2000 FEET. THE
TOP OF THE INVERSION WAS 4300 FEET WITH A TEMPERATURE OF 22 DEGREES
CELSIUS.

OVERALL...MODERATE CONFIDENCE IN 00Z TAF PACKAGE. LATEST SATELLITE
SHOWS STRATUS HAS DISSIPATED SAVE FOR STRATUS HUGGING THE VENTURA
AND LOS ANGELES COAST. OVERNIGHT...EXPECT STRATUS TO PUSH INTO MOST
COASTAL/VALLEY SITES. THE ONLY EXCEPTION WILL LIKELY BE KSBA WHERE
SOME NORTHERLY FLOW IS ANTICIPATED TO KEEP THE AIRFIELD CLEAR.

KLAX...MODERATE CONFIDENCE IN 00Z TAF. THERE IS A 30% CHANCE CIGS
COULD SCATTER OUT 00Z-05Z. HIGH CONFIDENCE IN MVFR CIGS OVERNIGHT
AND TUESDAY MORNING.

KBUR...MODERATE CONFIDENCE IN 00Z TAF. HIGH CONFIDENCE IN MVFR CIGS
RETURNING OVERNIGHT (WITH A CHANCE OF IFR CIGS)...BUT LOW CONFIDENCE
IN TIMING (+/- 3 HOURS OF CURRENT 08Z FORECAST).

&&

.MARINE...06/800 PM...

FOR THE OUTER WATERS...MODERATE CONFIDENCE IN NORTHWEST WINDS
REMAINING AT SMALL CRAFT LEVELS THROUGH TONIGHT ACROSS THE SOUTHERN
TWO THIRDS ZONES...AND BELOW SMALL CRAFT LEVELS FOR THE NORTHERN
ZONE. FOR TUESDAY AFTERNOON AND NIGHT...THERE IS A 50% CHANCE THAT
WINDS WILL INCREASE AGAIN TO SMALL CRAFT LEVELS ACROSS THE ENTIRE
OUTER WATERS. FOR WEDNESDAY THROUGH THE SECOND HALF OF THE
WEEK...THERE WILL BE A 30% CHANCE OF NORTHWEST GUSTS REACHING SMALL
CRAFT LEVELS.

FOR THE INNER WATERS...HIGH CONFIDENCE IN WESTERLY WINDS REMAINING
BELOW SMALL CRAFT LEVELS THROUGH THE WEEK. THERE IS A 20% CHANCE
EACH AFTERNOON AND EVENING OF GUSTS TO 25 KT ACROSS THE WESTERN
PORTIONS OF THE INNER WATERS...ESPECIALLY THE WESTERN PART OF THE
SANTA BARBARA CHANNEL.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...JLD/RAT
AVIATION...RAT
MARINE...RAT
SYNOPSIS...RAT

WWW.WEATHER.GOV/LOSANGELES



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