Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 010304
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
805 PM PDT FRI JUL 31 2015

.SYNOPSIS... A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS OVER THE
MOUNTAINS AND DESERTS EARLY THIS EVENING HAS ENDED...BUT ARE
EXPECTED AGAIN DURING THE AFTERNOON TO EVENING HOURS OVER THE
VENTURA MOUNTAINS SATURDAY AND SUNDAY. TEMPERATURES WILL BE NEAR
NORMAL THROUGH NEXT WEEK WITH AN OVERNIGHT MARINE LAYER THAT WILL
INCREASE BY MIDWEEK AS A LOW PRESSURE SYSTEM APPROACHES.

&&

.UPDATE...VISIBLE IMAGES THIS EVENING SHOWED MODERATE CUMULUS
DEVELOPMENT OVER THE MOUNTAINS OF LA/VENTURA/SBA COUNTIES AND
INTERIOR SLO COUNTY...BUT THUNDERSTORM ACTIVITY REMAINED NORTH AND
EAST OF THE AREA. WITH MODELS INDICATING GOOD INSTABILITY...MOISTURE
SEEMS TO BE THE LIMITING FACTOR AT THIS POINT AS SATELLITE PRECIP.
WATER IMAGES SHOWED STEADILY DECLINING VALUES THROUGH THE DAY. AMSU
IMAGES SHOWED A DECREASE FROM 1.5 INCHES OF PRECIPITABLE WATER EARLY
THIS MORNING TO 0.9 INCHES THIS EVENING. IN ADDITION...MODELS
INDICATE A STEADY DRYING TREND THROUGH THE EVENING. WILL REMOVE
MENTION OF SLIGHT CHANCE POPS FOR THIS EVENING OVER THE AREAS
MENTIONED ABOVE.

MARINE LAYER CLOUDS LINGERED NEAR THE CENTRAL COAST BEACHES THROUGH
THE AFTERNOON...AND AS OF 8 PM LOW CLOUDS ARE BEGINNING TO AFFECT
THE COASTAL AIRPORTS.  WITH ONSHORE FLOW ALONG THE COAST AND HEIGHTS
LOWERING ALOFT SLIGHTLY THROUGH THE NEXT 12 HOURS...EXPECT GOOD
INLAND PROGRESSION OF LOW CLOUDS OVERNIGHT. THE COASTAL VALLEYS WILL
ALL SEE AT LEAST PATCHY LOW CLOUDS AND FOG. ADDED PATCHY LOW CLOUD
COVERAGE TO THE VENTURA VALLEYS FOR THE UPDATE. THE SBA SOUTH COAST
REMAINS SLIGHTLY IN QUESTION...BUT EXPECT THAT LOW CLOUDS WILL MAKE
AN APPEARANCE LATE TONIGHT OR EARLY SATURDAY MORNING...MOVING IN
FROM THE SOUTHEAST.

.FROM PREVIOUS DISCUSSION (SAT-MON)...MODELS HAVE BACKED OFF ON
AVAILABLE MOISTURE TOMORROW SO HAVE ONLY INCLUDED SLIGHT CHANCE POPS
OVER THE VTU COUNTY MOUNTAINS AS PW DROPS TO AROUND A HALF INCH FOR
A CHANGE. FAIRLY SIMILAR CONDITIONS EXPECTED INTO SUNDAY AS THE AREA
IS FULLY WITHIN SOUTHWESTERLY FLOW AT UPPER LEVELS. STILL A VERY
SLIGHT CHANCE OF TRW OVER THE VTU COUNTY MOUNTAINS SUNDAY
AFTERNOON...AND WE COULD ACTUALLY SEE A FEW MORE CELLS DEVELOPING
COMPARED TO SATURDAY BASED ON A BRIEF BUMP UP IN PW FORECAST FOR
LATE SUNDAY FROM SOME INCREASING SUBTROPICAL MOISTURE PUSHING
THROUGH IN THE SW FLOW ALOFT. FOR NOW ALL AREAS ARE DRY FOR MONDAY
BUT MODELS DO FORECAST THAT MOISTURE HANGING AROUND ANOTHER DAY SO
IN LATER FORECASTS MAY HAVE TO INTRODUCE POPS FOR MONDAY SIMILAR TO
SUNDAY`S. NOT MUCH CHANGE AT ALL IN THE MARINE LAYER DEPTH FOR
SUNDAY MORNING THROUGH MONDAY MORNING SO SHOULD SEE SIMILAR
OVERNIGHT COASTAL STRATUS COVERAGE.

.LONG TERM (TUE-FRI)...SOUTHWESTERLY FLOW ALOFT CONTINUES THROUGH THE
EXTENDED PERIOD SO NOT MUCH IN THE WAY OF DAY TO DAY CHANGES IN THE
FORECAST. AREA WILL BE PRECIPITATION FREE ALONG WITH SIMILAR
OVERNIGHT COASTAL STRATUS COVERAGE EACH NIGHT AND TEMPERATURES AT OR
JUST BELOW NORMAL. UPPER LEVEL HIGH PRESSURE ATTEMPTS TO RE-
ESTABLISH ITSELF OVER NEW MEXICO WHICH TEASES US WITH THE RETURN OF
MONSOON MOISTURE TOWARD THE END OF THE PERIOD...BUT FOR NOW OUR
UPPER FLOW STAYS SOUTHWESTERLY ENOUGH TO KEEP ANY MONSOON MOISTURE
TO OUR SOUTH AND EAST.

&&

.AVIATION...01/0000Z...

THE MARINE LAYER AT KLAX AT 2300Z IS 875 FEET DEEP AND THE INVERSION
TOP IS AT 2075 FEET WITH A TEMP OF 26.3 DEGREES C.

MODERATE CONFIDENCE IN 00Z TAFS. EXPECT A SLIGHTLY DEEPER MARINE
LAYER AND ONSHORE FLOW TO BRING LOW CLOUDS OVER THE COASTAL AREAS
AND INTO THE COASTAL VALLEYS. THE TIMING AND HEIGHT OF THE CIGS IS
SOMEWHAT LOWER CERTAINTY. THERE IS A 20% CHANCE THAT KSBA WILL
REMAIN VFR OVERNIGHT. GUSTY ONSHORE WINDS WILL AFFECT DESERT
SITES...AND KPRB THIS EVENING.

KLAX...MODERATE CONFIDENCE IN 00Z TAF. ARRIVAL OF MARINE LAYER CIGS
MAY DIFFER UP TO 2 HRS FROM TAF TIME OF 04Z. 30% CHANCE THAT CONDS
WILL REMAIN MVFR OVERNIGHT. CLEARING MAY OCCUR UP TO 2 HRS LATER
THAN TAF TIME OF 19Z.

KBUR...LOW TO MODERATE CONFIDENCE IN 00Z TAF. ARRIVAL OF CIGS MAY
OCCUR +/- 2 HRS FROM TAF TIME OF 09Z. TIMING OF CLEARING SAT
AFTERNOON IS ALSO LOWER CERTAINTY.

&&

.MARINE...31/800 PM... LOW-END SMALL CRAFT ADVISORY CONDITIONS ARE
EXPECTED FROM POINT CONCEPTION TO SOUTH OF SAN NICOLAS ISLAND
THROUGH EARLY SATURDAY MORNING...WITH NORTHWEST WINDS GUSTING UP TO
25 KNOTS OVER THE WATERS NEAR/WEST OF THE CHANNEL ISLANDS SOUTHWARD
TO SAN NICOLAS ISLAND. THE SCA WINDS MAY CONTINUE SATURDAY MORNING
BUT ARE MORE LIKELY SATURDAY AFTERNOON AND EVENING. THERE IS A
CHANCE OF SCA CONDITIONS IN THE SANTA BARBARA BASIN SATURDAY
AFTERNOON THROUGH EARLY SUNDAY MORNING.

&&

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

&&

$$

PUBLIC...MJ/SMITH
AVIATION/MARINE...SMITH
SYNOPSIS...SETO/SMITH

WWW.WEATHER.GOV/LOSANGELES



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