Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 072218
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
320 PM PDT TUE JUL 7 2015

.SYNOPSIS...

A COOLING TREND WILL CONTINUE THROUGH THURSDAY AS LOW PRESSURE OFF
THE COAST MOVES OVERHEAD. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS
IN THE MOUNTAINS ON WEDNESDAY AND THURSDAY...WITH NIGHT TIME DRIZZLE
OR LIGHT RAIN POSSIBLE IN THE FOOTHILLS WEST OF THE MOUNTAINS.
GRADUAL WARMING IS EXPECTED OVER THE WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM (TONIGHT-FRI)...CLOSED UPPER LEVEL LOW PRESSURE SYSTEM
CONTINUES TO SPIN OFF THE COAST OF NORTHERN CALIFORNIA...MAINTAINING
STRONG ONSHORE FLOW AND AN UNUSUALLY DEEP MARINE LAYER PATTERN
ACROSS SOUTHERN CALIFORNIA.  SATELLITE IMAGERY SHOWING LOW CLOUDS
LINGERING ACROSS IMMEDIATE COASTAL AREAS OF VENTURA AND LOS ANGELES
COUNTIES OTHERWISE MOSTLY SUNNY SKIES PREVAIL. MARINE LAYER DEPTH
WAS AROUND 2700 FEET ACROSS THE LA BASIN TODAY. SLIGHT COOLING TREND
TODAY...WITH WARMEST VALLEYS ONLY CLIMBING INTO THE MID 80S.

AS THE UPPER LOW DRAWS CLOSER TO THE REGION THE NEXT COUPLE OF
DAYS...STRONG ONSHORE FLOW WILL REMAIN IN TACT AND THE MARINE LAYER
DEPTH WILL CONTINUE TO INCREASE. THIS DEEPENING OF THE MARINE LAYER
WILL BRING THE POTENTIAL FOR DRIZZLE THE NEXT COUPLE OF MORNINGS
ALONG WITH UNSEASONABLY COOLER TEMPERATURES. IN FACT...BY THURSDAY...
LANCASTER AND WOODLAND HILLS ARE ONLY EXPECTED TO PEAK AROUND
80 DEGREES...A GOOD 15 DEGREES BELOW NORMAL. WITH AN LAX-DAGGETT
GRADIENT PROJECTED TO BE AROUND +8 MB EACH AFTERNOON...WILL ALSO SEE GUSTY
ONSHORE WINDS EACH AFTERNOON AND EVENING ACROSS THE MOUNTAINS AND
ANTELOPE VALLEY. ISOLATED GUSTS AS HIGH AS 45 TO 50 MPH CAN BE
EXPECTED IN THE FOOTHILLS OF THE ANTELOPE VALLEY NEAR LAKE PALMDALE.
OTHER WIND CONCERN WILL BE GUSTY SUNDOWNER WINDS THIS EVENING ACROSS THE
WESTERN PORTIONS OF SBA SOUTH COAST (FROM GOLETA TO GAVIOTA)...WHERE LOCAL
GUSTS UP TO 35 MPH CAN BE EXPECTED.

OVER THE NEXT FEW DAYS...WILL HAVE TO KEEP AN EYE OUT FOR POTENTIAL
ISOLATED THUNDERSTORM ACTIVITY OVER THE MOUNTAINS...ESPECIALLY THE
VENTURA COUNTY MOUNTAINS. WHILE THERE IS FAIRLY GOOD
INSTABILITY/CAPE THIS AFTERNOON OVER THE VENTURA COUNTY
MOUNTAINS...MOISTURE IS LIMITED...AND THEREFORE ONLY EXPECTING SOME
CLOUD BUILDUPS. HOWEVER...ON WEDNESDAY AND THURSDAY...THERE IS
A LITTLE MORE AVAILABLE MOISTURE DUE TO THE APPROACHING LOW. IN
ADDITION...THERE WILL BE SOME LIFT ASSOCIATED WITH THE UPPER LOW ON
THURSDAY AS IT MOVES OVER LAND. THESE FACTORS COMBINED WITH MODERATE
AFTERNOON INSTABILITY/CAPE WARRANTS THE SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS
ON WEDNESDAY AND THURSDAY FOR THE MOUNTAINS (WITH VENTURA COUNTY
MOUNTAINS HAVING BEST THREAT). ON FRIDAY...THE UPPER LOW WILL SHIFT EAST
OF THE AREA AND A SLIGHT WARMING TREND WILL BEGIN.

.LONG TERM (SAT-TUE)... ALL MDLS ARE IN AGREEMENT THAT A BROAD
TROF WILL COVER THE WEST COAST WHILE A LARGE UPPER HIGH WILL SIT
OVER TEXAS AND NEW MEXICO. THE FLOW ALOFT WILL REMAIN FROM THE SOUTHWEST
OVER SOUTHWEST CALIFORNIA KEEPING ANY MONSOONAL MOISTURE WELL TO THE EAST
OF OUR AREA. ONSHORE FLOW WILL CONTINUE THROUGH THE PERIOD AND THERE WILL BE
PERSISTENT NIGHT THROUGH MORNING LOW CLOUD AND FOG FOR THE COASTS AND VLYS
OTHERWISE SKIES WILL BE MOSTLY CLEAR. MAX TEMPS WILL SLOWLY RISE
THROUGH THE PERIOD AS HGTS REBOUND AND THE ONSHORE FLOW WEAKENS.

&&

.AVIATION...07/1800Z.

AT 1732Z...THE MARINE INVERSION AT KLAX WAS BASED AT 2500 FEET. THE
TOP OF THE INVERSION WAS 4200 FEET WITH A TEMPERATURE OF 20 DEGREES
CELSIUS.

GOOD CONFIDENCE IN THE 18Z TAF PACKAGE. LOOKS LIKE ANOTHER SLOW
CLEARING DAY WTH A RELATIVELY DEEP MARINE LAYER. SOME CLEARING IS
POSSIBLE IN COASTAL SECTIONS SOUTH OF POINT CONCEPTION THIS
AFTERNOON DESPITE THE PESSIMISTIC APPROACH OF THE TAFS. MVFR
CONDITIONS ARE EXPECTED TONIGHT IN THE VALLEYS AND MVFR TO VFR
CEILINGS IN THE COASTAL SECTIONS. NORTH OF POINT CONCEPTION THE
MARINE CLOUDS ARE A BIT MORE SCARCE BUT THEY WILL ALSO RETURN TO THE
CENTRAL COAST AGAIN TONIGHT. THE ANTELOPE VALLEY WILL HAVE ANOTHER
ROUND OF GUSTY SOUTHWEST WINDS THIS AFTERNOON.

KLAX...GOOD CONFIDENCE IN THE 18Z TAF. SKIES ARE EXPECTED TO REMAIN
MOSTLY CLOUDY THIS AFTERNOON WITH A DEEPER MARINE LAYER FOR TONIGHT
AND WEDNESDAY MORNING. THERE IS A 30 PERCENT CHANCE OF CLEARING THIS
AFTERNOON.

KBUR...GOOD CONFIDENCE IN THE 18Z TAF. THERE IS A 30 PERCENT CHANCE
OF THE MARINE CLOUDS MOVING IN PLUS OR MINUS TWO HOURS FROM THE
FORECASTED TIME.

&&

.MARINE...07/200 PM...

FOR THE OUTER WATERS...MODERATE CONFIDENCE IN NORTHWEST WINDS
REMAINING AT SMALL CRAFT LEVELS THROUGH EARLY WEDNESDAY MORNING FROM
POINT SAL SOUTH. 30 PERCENT CHANCE THAT SMALL CRAFT ADVISORY WILL BE
NEEDED FOR ZONE 670 THIS AFTERNOON. THERE COULD BE LOCAL GUSTS TO 25
KNOTS BETWEEN PIEDRAS BLANCAS AND POINT SAL. 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 30% CHANCE
THIS 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. LOWER CHANCES THE FOLLOWING FEW DAYS.

&&

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

&&

$$

PUBLIC...GOMBERG
AVIATION/MARINE...SWEET
SYNOPSIS...SUKUP

WWW.WEATHER.GOV/LOSANGELES


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