953 
FXUS66 KLOX 090536
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
930 PM PST SUN JAN 8 2012

NEW AVIATION DISCUSSION

.SYNOPSIS...

HIGH PRESSURE AND OFFSHORE FLOW WILL KEEP THE AREA DRY AND WARM
THROUGH MONDAY. FOR TUESDAY AND WEDNESDAY AN AREA OF LOW PRESSURE
WILL IMPACT THE AREA...BRINGING COOLER TEMPERATURES. FOR THE
SECOND HALF OF THE WEEK...DRY CONDITIONS ARE EXPECTED TO CONTINUE
WITH TEMPERATURES NEAR OR SLIGHTLY ABOVE SEASONAL NORMALS.

&&

.UPDATE...

BREEZY CONDITIONS CONTINUE ACROSS THE AREA THIS EVENING...WITH
SOME WINDY AREAS OCCURRING IN THE MOUNTAINS. KLAX-KDAG SURFACE
PRESSURE GRADIENTS REMAIN OFFSHORE THIS EVENING...WITH KLAX-KDAG
GRADIENT NEAR -4 MB. A MARGINAL WIND ADVISORY REMAINS IN EFFECT.
NAM-WRF SOLUTIONS DO INDICATE A POSSIBLE STRENGTHENING OF THE
WINDS FURTHER TONIGHT...BUT THE SITUATION WILL HAVE TO BE
MONITORED FOR FURTHER DEVELOPMENT.

WITH A DRY AIR MASS IN PLACE ACROSS THE AREA...A LACK OF WIND IN
THE WIND-SHELTERED AREAS AND LOW DEWPOINTS WILL ALLOW
RADIATIONAL COOLING EFFECTS TO BE MORE EFFICIENT TONIGHT. MOST
LOCATIONS IN THE DESERT AND IN THE INTERIOR VALLEYS WILL SEE SUB-
FREEZING TEMPERATURES DEVELOP TONIGHT...WITH THE THREAT OF
TEMPERATURES NEAR FREEZING IN THE OJAI AND SANTA YNEZ VALLEYS. A
FROST ADVISORY WILL LIKELY BE ADDED TO THE PACKAGE FOR THE OJAI
AND SANTA YNEZ VALLEYS. DUE TO PRIOR ISSUANCES OF FROST/FREEZE
PRODUCT FOR THE ANTELOPE VALLEY AND THE INTERIOR VALLEYS...SUCH AS
CUYAMA...CALIFORNIA...AND UPPER SALINAS RIVER VALLEYS...NO FREEZE
HEADLINES WILL BE ADDED THIS EVENING. TEMPERATURES WILL ALSO BE
LOWERED FOR SOME AREAS IN THE PACKAGE AS SOME MOUNTAIN AREAS SUCH
AS THE LOCKWOOD VALLEY ARE APPROACHING THEIR OVERNIGHT LOWS
ALREADY.

THE LATEST WATER VAPOR IMAGERY INDICATE A UPPER-LEVEL RIDGE OF
HIGH PRESSURE BUILDING IN FROM THE WEST. A WARMING TREND WILL
CONTINUE THROUGH MONDAY AS THE RIDGE AXIS SHIFT OVER THE REGION
ON MONDAY.

&&

.PREV DISCUSSION...

SHORT TERM...THE RIDGE WILL SHIFT FURTHER INLAND TUESDAY AS AN
UPPER LOW PRESSURE SYSTEM APPROACHES THE WEST COAST. THE MODELS
ARE COMING INTO BETTER AGREEMENT WITH THE APPROACHING
LOW...ALTHOUGH SOME DIFFERENCES IN STRENGTH AND LOCATION CONTINUE.
EXPECT A COOLER DAY TUESDAY WITH INCREASING HIGH CLOUDS AS THE LOW
APPROACHES.

BY WEDNESDAY A LARGE UPPER LOW IS SOMEWHERE OVER/OFFSHORE FROM THE S 
CALIFORNIA COAST...DEPENDING ON THE MODEL. SOLUTIONS RANGE FROM A 
549 MB LOW RIGHT OVER PT CONCEPTION TO A 557 MB LOW ABOUT 500 NM 
WEST OF THAT LOCATION. SO FAR ONLY THE NAM12 SHOWS ANY PRECIPITATION 
OVER THE AREA. DECIDED TO CONTINUE THE 10 PERCENT POPS OVER THE AREA 
TO INDICATE THE POTENTIAL FOR RAINFALL ON WEDNESDAY. 

LONG TERM...BY THURSDAY THE LATEST GFS AND ECMWF HAVE MUCH BETTER
AGREEMENT THAN PRIOR RUNS WITH A 555 MB CLOSED LOW NEAR 30 N AND
127 W...WHILE THE GEM HAS SHIFTED THE LOW SOUTHWARD TO THE N BAJA
COAST. THE GFS/EC SLOWLY MOVE THE LOW EAST (EC) AND NORTHEAST
(GFS) TOWARD THE COAST THROUGH FRIDAY...AND THEN INLAND OVER THE
WEEKEND. BOTH SOLUTIONS WOULD BRING SOME PRECIPITATION TO
SOUTHWEST CALIFORNIA ON SATURDAY BUT CONSIDERING RECENT RUN TO RUN
MODEL CONSISTENCY...DO NOT FEEL COMFORTABLE ADDING MUCH IN THE WAY
OF POPS FOR LATE IN THE EXTENDED.

&&

.AVIATION...

09/0540Z.

VERY HIGH CONFIDENCE IN CAVU TAFS WITH ONLY A 200 PERCENT CHANCE OF 
LIFR CONDS AT KPRB 10Z-17Z.

KLAX...VERY HIGH CONFIDENCE IN CAVU TAF WITH ANY EAST WINDS 
REMAINING LESS THAN 7 KNOTS.

KBUR...VERY HIGH CONFIDENCE IN CAVU TAF. LGT TURBC SFC-060 TIL 17Z.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).

&&

$$

PUBLIC...HALL/SMITH
AVIATION...ASR
SYNOPSIS...RAT

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