991 
FXUS66 KLOX 060347
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
847 PM PDT WED SEP 5 2012

.SYNOPSIS...

MOISTURE FROM THE REMNANTS OF TROPICAL STORM JOHN WILL CONTINUE
TO BRING THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS ACROSS THE
REGION THROUGH THURSDAY. A WARMING AND DRYING TREND WILL DEVELOP
ON FRIDAY AS HIGH PRESSURE BUILDS OVER THE REGION. HIGH PRESSURE
WILL BREAK DOWN EARLY NEXT WEEK FOR A COOLING TREND AND STRONGER
ONSHORE FLOW.

&&

.UPDATE...

EARLIER SATELLITE PICTURES FROM THE REMNANTS OF WHAT WAS TROPICAL
STORM JOHN WERE VERY IMPRESSIVE. A BAND OF LIGHT SHOWERS REMAINS
STRETCHED OVER THE AREA THIS EVENING. RAINFALL TOTALS HAVE RANGED
FROM TRACE AMOUNTS UP TO 0.05 INCH TODAY. TEMPERATURES WERE MUCH
COOLER FROM THE RAIN-COOLED AIR MASS IN PLACE. THE BAND OF SHOWERS
IS STARTING TO WEAKEN THIS EVENING...STRUGGLING TO PUSH NORTH OF
POINT CONCEPTION. CURRENT FORECAST HAS ISOLATED SHOWERS AND
THUNDERSTORMS THROUGH THURSDAY...AND IT SEEMS AGREEABLE WITH THE
MOIST AIR MASS IN PLACE. SATELLITE PRECIPITABLE WATER VALUES ARE
AROUND 1.60 INCHES THIS EVENING. MODEL SOLUTIONS CONTINUE TO
INDICATE A 850-700 MB DEWPOINTS NEAR 8 CELSIUS...AND 850-700 MB
MIXING RATIOS BETWEEN 8 AND 10 G/KG THROUGH THURSDAY. CONVECTION
ON THURSDAY SHOULD BE OROGRAPHICALLY FOCUSED...FIRING OVER THE
MOUNTAINS AND DRIFTING TOWARD THE NORTHEAST. WITH THE BAND SLOWING
AND WEAKENING THIS EVENING...MENTION OF ISOLATED SHOWERS AND
THUNDERSTORMS NORTH OF POINT CONCEPTION WILL BE LEFT IN FOR THE
CURRENT TIME.

&&

.PREV DISCUSSION...

SHORT TERM...HIGH PRESSURE BUILDS BACK ACROSS SOUTHERN CAL
STARTING ON FRIDAY AS THE MOISTURE PLUME SHIFTS TO OUR WEST AND
NORTH. EXPECT WARMER AND DRIER CONDITIONS RIGHT THROUGH SATURDAY.
TEMPERATURES WILL PUSH TO THE CENTURY MARK OR HIGHER ON SATURDAY
ACROSS THE INTERIOR VALLEYS...ANTELOPE VALLEY AND THE PASO ROBLES
AREA WITH THIS BEING THE HOTTEST DAY OF THE ENTIRE FORECAST
PERIOD.

LONG TERM...IT SHOULD REMAIN WARM AND DRY ON SUNDAY BUT MAYBE A
COUPLE OF DEGREES SHORT OF SATURDAY'S HIGHS. THE HIGH PRESSURE
RIDGE WILL BEGIN TO BREAK DOWN EARLY NEXT WEEK WITH SLIGHTLY
COOLER TEMPERATURES EXPECTED MONDAY AND TUESDAY. MODEL DATA
INDICATES A WEAK LOW PRESSURE AREA AND MONSOON MOISTURE DRIFTING
UP FROM BAJA THAT COULD GIVE LOS ANGELES COUNTY MOUNTAINS/DESERTS
A BRUSH WITH CONVECTION ON SUNDAY AND MONDAY. WILL NEED TO KEEP AN
EYE ON THIS BUT FOR NOW IT LOOKS LIKE THIS MOISTURE WILL STAY
SOUTH AND EAST OF US. ANOTHER WEAK LOW PRESSURE AREA TAKES UP
RESIDENCE WELL OFF THE WEST COAST BY TUESDAY (SIMILAR TO TODAY)
AND SHOULD HELP BUILD THE RIDGE OVER SOUTHERN CAL THROUGH
WEDNESDAY FOR ANOTHER WARM-UP BY MIDWEEK.

&&

.AVIATION...05/2358Z.

NORTH OF POINT CONCEPTION...THERE IS A 20 PERCENT CHANCE OF 
THUNDERSTORM THROUGH 11Z. AT COASTAL TERMINALS...THERE IS A CHANCE 
OF VLIFR TO LIFR CONDITIONS BETWEEN 08Z AND 16Z.

SOUTH OF POINT CONCEPTION...THERE IS A 20 PERCENT CHANCE OF A 
THUNDERSTORMS AT KSBA THROUGH 03Z. AT COASTAL TERMINALS NORTH OF 
KNTD...THERE IS A CHANCE OF VLIFR TO LIFR CONDITIONS BETWEEN 10Z AND 
16Z.

KLAX...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD. THERE IS A 
10 PERCENT CHANCE OF LIFR TO IFR CONDITIONS.

KBUR...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE. 

&&

$$

PUBLIC...HALL/BOLDT
AVIATION...HALL
SYNOPSIS...HALL

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