787 
FXUS66 KLOX 041839
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1030 AM PST SUN NOV 4 2012

...UPDATED FIRE WEATHER SECTION...

.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE REGION THROUGH MONDAY. INCREASING 
OFFSHORE FLOW WILL BRING CLEAR SKIES AND WELL ABOVE NORMAL 
TEMPERATURES TO THE AREA THROUGH TUESDAY. A COLD UPPER LEVEL TROUGH 
OF LOW PRESSURE WILL MOVE INTO SOUTHERN CALIFORNIA BY LATE IN THE 
WEEK WITH PLENTY OF CLOUDS...A CHANCE OF RAIN AND MOUNTAIN 
SNOW...AND BELOW NORMAL TEMPERATURES.

&&

.SHORT TERM (TODAY-WED)...
.MID-MORNING UPDATE...
CLEAR SKIES THROUGHOUT THE CWA THIS MORNING.  THE PRESSURE GRADIENT 
LAX-DAG IS STRONGER THIS MORNING THAT YESTERDAY MORNING AND WIND 
SPEEDS HAVE COME UP A BIT BUT STILL LUKS LIKE TONIGHT WILL BE THE 
PEAK.  SUSTAINED WINDS WILL REMAIN WELL BELOW WIND ADVISORY CRITERIA 
BUT GUSTS MAY NIP AT THE BOTTOM IN SOME WIND FAVORED LOCATIONS BUT 
THERE ARE NO PLANS TO ISSUE A WAD ATTM.  WILL KEEP AN EYE ON IT.

PRIMARY FOCUS FOR TODAY WILL BE ASSESSING THE WEATHER SYSTEM COMING 
IN LATER IN THE WORK WEEK.  THE MARINE LAYER WILL COME BACK IN MOST 
AREAS BY WEDNESDAY MORNING AND BY THURSDAY LIGHT PRECIPITATION WILL 
BE KNOCKING IN THE NORTHERN COUNTIES.  PRECIP SHOULD BE IN MOST 
AREAS BY LATE FRIDAY.  CONTINUE TO BE A BIT WARY OF TIMING BOTH 
COMING AND GOING AND THE WET STUFF MAY LINGER INTO SUNDAY MORNING 
BUT FRIDAY AND SATURDAY LUK TO BE THE PRIME TIME.

A COLD AIRMASS WILL BE BROUGHT INTO THE REGION WITH THIS SYSTEM AND 
THE HIGHER ELEVATIONS WILL RECEIVE SOME SNOW.  NOT SURE YET JUST HOW 
COLD BUT A LINGERING SYSTEM TYPICALLY ALLOWS FOR THE COLD AIR TO 
MINGLE LONGER WITH THE MOIST AIRMASS SO THERE IS AT LEAST A SLIGHT 
POSSIBILITY OF DECENT EARLY SEASON SNOWFALL AT THOSE LEVELS. 

.MORNING DISCUSSION...
SKIES ARE CLEAR SAVE FOR A SMALL PATCH OF CLOUDS NEAR LONG BEACH. 
THIS CLOUD PATCH SHOULD DISSIPATE EARLY IN THE FACE OF INCREASING 
OFFSHORE FLOW FROM BOTH THE NORTH AND EAST. CURRENT GRADIENTS ARE 2 
MB OFFSHORE FROM THE EAST AND 4 MB OFFSHORE FROM THE NORTH. THERE IS 
NO UPPER SUPPORT AND NO COLD AIR ADVECTION SO CANYON WINDS WILL BE 
LIMITED AND WEAK. MAX TEMPS WILL CONTINUE TO CLIMB WITH 586 DM HGTS 
OVERHEAD AND THE OFFSHORE FLOW. MAX TEMPS WILL BE 10 TO 20 DEGREES 
ABOVE NORMAL.

MONDAY WILL BE THE WARMEST DAY WITH A 591 UPPER HIGH SITTING ATOP OF 
THE NORTHERN SECTION OF THE STATE. BETTER OFFSHORE FLOW WILL PRODUCE 
STRONGER AND MORE WIDESPREAD NORTHEAST CANYON WINDS BUT THEY WILL 
STILL BE BELOW ADVISORY CRITERIA. MAX TEMPS WILL BUMP UP ANOTHER FEW 
DEGREES. A TYPICAL SANTA ANA TEMP PATTERN WITH THE COASTS THE 
WARMEST AREAS SINCE THEY RECEIVE THE MOST ADIABATIC COMPRESSION.

THE HIGH LOOPS OVER THE STATE AND INTO NEVADA TUESDAY. OFFSHORE FLOW 
RELAXES. IT WILL STILL BE CLOUD FREE BUT MAX TEMPS WILL DROP 3 TO 6 
DEGREES AND MAYBE MORE RIGHT AT THE BEACHES.

ON WEDNESDAY THE RIDGE EXITS THE AREA AND A WEAK TROF MOVES INTO THE 
STATE. THE TROF DOES NOT BRING ANY MOISTURE WITH IT AND THERE WILL 
STILL BE OFFSHORE FLOW IN THE MORNING SO SKIES WILL REMAIN CLEAR. 
THE GRADIENTS SHIFT ONSHORE DURING THE DAY AND HGTS FALL THROUGH THE 
DAY AS WELL. MAX TEMPS WILL RESPOND BY DROPPING BY 5 TO 10 DEGREES. 
MAX TEMPS...HOWEVER...WILL STILL REMAIN 3 OR SO DEGREES ABOVE NORMAL 
AWAY FROM THE COAST.

.LONG TERM (THU-SAT)...
ALL LONG RANGE MDLS AGREE THAT A COLD PAC NW LOW WILL MOVE DOWN THE 
WEST COAST STARTING THURSDAY AND THEN SWEEP EASTWARD ALONG THE CA/OR 
BORDER FRIDAY. LARGE SCALE MOIST CYCLONIC FLOW WILL PERSIST OVER THE 
AREA THROUGH SATURDAY. HGTS DROP FROM 573 DM THURSDAY MORNING TO 550 
DM BY FRIDAY NIGHT. THIS IS A COLD BUT FAIRLY DRY SYSTEM AND IT IS 
GOING TO BRING MORE CLOUDS THAN RAIN. BOTH THE EC AND GFS HAVE 
SLOWED THE PROGRESS OF THE INITIAL BAND OF RAIN AND ADJUSTED TO 
FORECAST TO KEEP THURSDAY DRY. A SLIGHT CHANCE OF RAIN WILL 
OVERSPREAD THE AREA THU NIGHT. THERE WILL BE A SLIGHT CHC OF SHOWERS 
THU NIGHT INTO SATURDAY. SOME RAIN IS ALMOST A CERTAINTY IN THE 
PERIOD BUT TIMING THE IMPULSES IS IMPOSSIBLE THIS FAR AWAY SO THE 
POPS ARE LOW FOR THE INDIVIDUAL PERIODS. RAINFALL TOTALS WILL BE ON 
THE LOW SIDE AS THERE IS NOT MUCH MOISTURE AND NO SOUTH FLOW. THE 
BEST CHC FOR RAIN AND THE HIGHEST RAINFALL AMOUNTS WILL BE NORTH OF 
POINT CONCEPTION. THERE WILL BE SNOW IN THE MOUNTAINS BUT LIKELY 
ABOVE THE CRITICAL PASS LEVELS.

&&

.AVIATION...04/1800Z.

MID/UPPER LEVEL RIDGE OF HIGH PRESSURE CENTERED OVER THE EASTERN PAC 
AND EXTENDING OVER NORTHERN CALIFORNIA WILL SHIFT SOUTH. 
UPPER LEVEL MODERATE NORTHEAST WINDS WILL BECOME LIGHT EAST AFTER 
05/20Z WHILE MID LEVEL LIGHT TO MODERATE EAST WINDS PREVAIL OVER THE 
AREA. MARINE INVERSION WITH AN ISOLATED CLOUD FIELD WITH TOPS BELOW 
.5KFT THIS MORNING WILL PERSIST. MIXED WEAK ONSHORE AND 
NORTHEASTERLY PRESSURE GRADIENT THROUGH 05/02Z...THEN WEAK TO 
MODERATE NORTHEASTERLY GRADIENT BETWEEN 05/06-05/18Z AND MIXED WEAK 
ONSHORE AND OFFSHORE GRADIENT AFTER 04/18Z.  

KLAX...CURRENT SKY/VSBY CONDITIONS LIKELY THROUGH THE PERIOD. LOW 
LEVEL ONSHORE WINDS BETWEEN 04/19-05/05Z AND AFTER 
05/19Z...OTHERWISE EAST WINDS BETWEEN 05/06-05/19Z AND VERY LIKELY 
LESS THAN 10KT.

KBUR...VERY LIKELY CURRENT SKY/VSBY CONDITIONS WILL PERSIST. 

VIRTUALLY CERTAIN - 95-100%
VERY LIKELY       - 80-95%
LIKELY            - 60-80%
CHANCE            - 30-60%
VERY UNLIKELY     - 20% OR LESS

&&

.FIRE WEATHER...
ELEVATED FIRE DANGER ACROSS THE REGION SUNDAY INTO MONDAY AS 
BREEZY OFFSHORE WINDS BRING MUCH WARMER AND DRIER CONDITIONS. WHILE
OFFSHORE WINDS DO NOT LOOK AS STRONG OR WIDESPREAD AS WHAT OCCURRED
LAST WEEK...THERE WILL BE LIKELY BE A PERIOD OF CRITICAL FIRE WEATHER
CONDITIONS IN THE MOUNTAINS OF LOS ANGELES AND VENTURA COUNTIES TONIGHT
THROUGH EARLY MONDAY AFTERNOON...WHERE RED FLAG WARNINGS ARE IN EFFECT. 
CURRENT LAX-DAGGETT GRADIENT AT -4.1 MB THIS MORNING...SOMEWHAT STRONGER
THAN MODELS WERE ADVERTISING. AS SURFACE HIGH PRESSURE CONTINUES TO
BUILD OVER THE GREAT BASIN...THE OFFSHORE GRADIENT IS EXPECTED TO
BE SLIGHTLY STRONGER FOR MONDAY MORNING. 

WITH MODELS STILL ON TRACK FOR PEAK OF OFFSHORE GRADIENTS AND UPPER LEVEL
WIND SUPPORT FOR TONIGHT THROUGH MONDAY MORNING. DURING THIS TIME...STRONGEST
WINDS WILL BE FOCUSED IN THE MOUNTAINS OF LOS ANGELES AND VENTURA COUNTIES
(GUSTS BETWEEN 30 AND 40 MPH) COINCIDING WITH HUMIDITIES AROUND 10 PERCENT OR
LESS. AS A RESULT...HIGHER CONFIDENCE THAT SUFFICIENT DURATIONS OF RED FLAG
CONDITIONS WILL BE MET FOR THE MOUNTAINS. FOR THE SANTA MONICA
MOUNTAINS AND VALLEYS (ESPECIALLY SANTA CLARITA VALLEY AND EASTERN
VENTURA VALLEYS)...THERE WILL LIKELY BE GUSTS IN THE 25 TO 35 MPH RANGE
WITH HUMIDITIES IN THE UPPER SINGLE DIGITS AND LOWER TEENS. WHILE THESE
AREAS COULD SEE BRIEF CRITICAL FIRE WEATHER CONDITIONS...IT NO LONGER
APPEARS THERE WILL BE A SUFFICIENTLY LONG DURATION TO WARRANT RED
FLAG WARNINGS FOR THE LOWER ELEVATIONS. WHILE RED FLAG CONDITIONS MAY
NOT BE MET FOR LOWER ELEVATIONS...THE PROJECTED WEATHER CONDITIONS COMBINED
WITH VERY DRY FUELS CERTAINLY LEADS TO ELEVATED FIRE DANGER THE NEXT
COUPLE OF DAYS. VERY POOR HUMIDITY RECOVERIES TONIGHT AND MONDAY NIGHT
ACROSS WIND EXPOSED LOCATIONS AND FOOTHILLS WILL ADD TO THE FIRE
DANGER ACROSS THE DISTRICT. CONTINUED VERY WARM AND DRY ON TUESDAY...WITH
LIGHTER OFFSHORE WINDS DURING THE MORNING HOURS. BY TUESDAY AFTERNOON...ONSHORE
WINDS WILL BECOME MORE WIDESPREAD WITH A CONTINUED FIRE WEATHER CONCERN
DUE TO LINGERING LOW HUMIDITIES.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING (SEE LAXRFWLOX).

&&

$$

PUBLIC...KJ
FIRE...GOMBERG
SYNOPSIS...SWEET

WWW.WEATHER.GOV/LOSANGELES