Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 050311
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
810 PM PDT SAT JUL 4 2015

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS... THERE WILL BE NIGHT THROUGH MORNING LOW CLOUDS AND FOG
IN COASTAL AND SOME VALLEY AREAS THROUGH EARLY NEXT WEEK...WITH
TEMPERATURES NEAR TO SLIGHTLY ABOVE NORMAL. LOW PRESSURE WILL BRING
A DEEPER MARINE LAYER WEDNESDAY THROUGH FRIDAY...WITH MORE EXTENSIVE
NIGHT THROUGH MORNING LOW CLOUDS AND FOG WEST OF THE MOUNTAINS...
AND SLIGHTLY BELOW NORMAL TEMPERATURES IN MOST AREAS.

&&

.SHORT TERM (TONIGHT-TUE)...EVENING UPDATE

AS EXPECTED...TODAY`S HIGHS ACROSS THE VALLEYS TRENDED COOLER 5 TO
10 DEGREES IN MOST AREAS...WHILE THE COASTAL AREAS WERE ABOUT THE
SAME OR A DEGREE OR TWO COOLER TODAY. THE ONE AREA THAT WARMED UP
FROM YESTERDAY WAS THE ANTELOPE VALLEY...LIKELY FROM DOWNSLOPING
WINDS OVER THE SAN GABRIEL MTNS. LATEST VIS SAT IMAGERY INDICATED
LOW CLOUDS ALREADY PUSHING IN ACROSS MANY IMMEDIATE COASTAL AREAS
THIS EVENING. EXPECT THE LOW CLOUDS TO SURGE INLAND LATER THIS
EVENING. LATEST AMDAR SOUNDING NEAR LAX INDICATED THE MARINE LAYER
AROUND 1600 FT DEEP ALREADY. THIS SHOULD BE GOOD NEWS FOR PEOPLE
WATCHING FIREWORKS ALONG THE LOS ANGELES COUNTY COAST AS THE BASE OF
THE CLOUDS WERE AROUND 1200 FT DEEP. CURRENTLY OXNARD AIRPORT WAS
SHOWING A BASE OF 700 FT...BUT WOULD NOT BE SURPRISED IF IT RAISED A
FEW HUNDRED BY 9 PM THIS EVENING. NEVERTHELESS...EXPECT LOW CLOUDS
ACROSS MOST COASTAL AREAS THIS EVENING..SPREADING INLAND OVERNIGHT
INTO MOST COASTAL VALLEYS. PEOPLE WATCHING FIREWORKS ACROSS THE
CENTRAL COAST...I.E. PISMO BEACH OR CUYACOS WILL ALSO DEAL WITH LOW
CLOUDS...WITH CLOUD BASES A BIT LOWER.

SYNOPTICALLY...THIS IS MUCH MORE OF A JUNE GLOOM PATTERN THAN THE
EARLIER HUMID MONSOON PATTERN WE WERE STUCK IN FOR MOST OF THE PAST
WEEK. A REX BLOCK PATTERN OFF THE COAST WITH AN EXPANSIVE UPPER LOW
OFF THE CALIFORNIA COAST...AND A STRONG 590 DM HIGH JUST OFF THE
CANADIAN WEST COAST. THE UPPER LOW WILL MOVE CLOSER TO NORTHERN
CALIFORNIA OVER THE NEXT TWO DAYS ALLOWING FOR THE UPPER TROUGH TO
LINGER OVER THE REGION. EXPECT THE COOLING TREND TO CONTINUE ONCE
AGAIN TOMORROW AND MONDAY A FEW DEGREES WITH LITTLE CHANGE FOR
TUESDAY. THERE WILL CONTINUE TO BE NIGHT THROUGH MORNING LOW CLOUDS
AND PATCHY FOG IN SOME VALLEY LOCATIONS. THERE SHOULD BE A FEW
DEGREES OF COOLING ACROSS THE ANTELOPE VALLEY TOMORROW AS HEIGHTS
SHOULD CONTINUE TO LOWER A BIT. STRONG ONSHORE GRADIENTS WILL
CONTINUE THROUGH TUE ALLOWING FOR GUSTY SW WINDS ACROSS PORTIONS OF
THE LA COUNTY MTNS INTO THE ANTELOPE VALLEY AND ADJACENT FOOTHILLS
EACH AFTERNOON. THERE COULD BE A FEW GUSTS TO 45 MPH AROUND LAKE
PALMDALE. THERE WILL BE SOME CUMULUS BUILDUPS OVER THE VENTURA
COUNTY MTNS SUNDAY AFTERNOON AND EVENING AS INSTABILITY PARAMETERS
PUT A BULLSEYE OVER THAT AREA. ALTHOUGH THERE WILL BE RELATIVELY
HIGH CAPE...LIFTED INDEX AROUND -7 AND K INDEX AROUND 40...THERE
WILL BE A THIN POOL OF MOISTURE AROUND 700 MB TO WORK WITH. NOT
ENOUGH TO INITIATE ELEVATED THUNDERSTORMS TOMORROW AFTERNOON.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (WED-SAT)...THE UPPER LOW WILL SHIFT SLOWLY EASTWARD ON
WEDNESDAY...PUSHING ONSHORE OVER THE BAY AREA THURSDAY AND THEN
LIFTING TO THE NORTHEAST MORE RAPIDLY FRIDAY INTO SATURDAY. THE MAIN
EFFECT OVER SOUTHWEST CALIFORNIA WILL BE TO FURTHER DEEPEN THE
MARINE LAYER SO THAT IT WILL EXTEND OVER THE INLAND VALLEYS AND THE
LOWER COASTAL MOUNTAIN SLOPES. SOME DRIZZLE MAY ALSO BE POSSIBLE AS
THIS OCCURS. A SLOW COOLING TREND WILL ALSO OCCUR THROUGH FRIDAY.

&&

.AVIATION...05/0110Z...

AT 0100Z...THE MARINE INVERSION AT KLAX WAS BASED AT 1300 FEET. THE
TOP OF THE INVERSION WAS 5300 FEET WITH A TEMPERATURE OF 24 DEGREES
CELSIUS.

OVERALL...MODERATE CONFIDENCE IN 00Z TAF PACKAGE. EXPECT A SIMILAR
STRATUS PATTERN OVER THE NEXT 24 HOURS AS PERSISTENCE FORECAT IS
EXPECTED. FOR TONIGHT...EXPECT STRATUS TO MOVE INLAND
OVERNIGHT...PUSHING INTO THE COASTAL VALLEYS WITH MVFR/IFR CIGS
LIKELY AT ALL COASTAL/VALLEY TAF SITES. LOW CLOUDS SHOULD SEE
SIMILAR TIMES FOR SCOURING OUT...WITH HIGHER CONFIDENCE ACROSS
COASTAL VALLEY LOCATIONS.

KLAX...LOW CONFIDENCE IN 00Z TAF. THERE IS A 30% CHANCE THAT MVFR
CIGS WILL NOT SCATTER OUT SUNDAY AFTERNOON. FOR TONIGHT...HIGH
CONFIDENCE IN RETURN OF CIGS...BUT ONLY MODERATE CONFIDENCE IN
FLIGHT CATEGORY (CIGS COULD REMAIN AT MVFR LEVELS OVERNIGHT).

KBUR...MODERATE CONFIDENCE IN 00Z TAF. HIGH CONFIDENCE IN VFR CONDS
THRU THIS EVENING. OVERNIGHT...HIGH CONFIDENCE IN RETURN OF IFR CIGS
BUT MODERATE CONFIDENCE IN TIMING (+/- 2 HOURS OF CURRENT 08Z
FORECAST).

&&

.MARINE...04/130 PM...

FOR THE OUTER WATERS...HIGH CONFIDENCE IN WEST TO NORTHWEST WINDS
REMAINING BELOW SMALL CRAFT ADVISORY LEVELS THROUGH SUNDAY NIGHT
(ALTHOUGH THERE MAY BE SOME LOCAL GUSTS TO 25 KT IN THE AFTERNOON
AND EVENING HOURS). FOR MONDAY THROUGH WEDNESDAY...THE WINDS WILL
INCREASE A BIT...AND THERE IS A GOOD CHANCE OF SMALL CRAFT ADVISORY
CONDITIONS DEVELOPING.

FOR THE INNER WATERS...HIGH CONFIDENCE IN WESTERLY WINDS REMAINING
BELOW SMALL CRAFT ADVISORY LEVELS THROUGH SUNDAY. FROM MONDAY
THROUGH WEDNESDAY...THE WINDS WILL INCREASE A BIT. THERE IS A SLIGHT
CHANCE OF SMALL CRAFT ADVISORY LEVEL GUSTS ACROSS WESTERN SECTIONS
EACH AFTERNOON AND EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...KAPLAN/SMITH
AVIATION/MARINE...CK/RAT
SYNOPSIS...SUKUP

WWW.WEATHER.GOV/LOSANGELES


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