Dense Fog Advisory 21, NWS Los Angeles, CA

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
330 AM PST WED NOV 30 2011

.SYNOPSIS...
A COLD UPPER LOW PRESSURE SYSTEM OVER SOUTHEASTERN CALIFORNIA WILL
BRING STRONG GUSTY SANTA ANA WINDS TO THE VENTURA AND LOS ANGELES
COUNTIES BEGINNING LATE TONIGHT AND LASTING INTO FRIDAY.
TEMPERATURES WILL DROP BELOW SEASONAL NORMALS BY THURSDAY AND
FRIDAY...RETURNING TO AROUND NORMAL FOR THE WEEKEND. WEAKER OFFSHORE
WINDS MAY EXTEND THROUGH THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
WEAK NW FLOW WITH 580 DM HGTS OVER THE AREA. WEAK OFFSHORE FLOW FROM
THE EAST AND MODERATE OFFSHORE FLOW FROM THE NORTH. NOT ENOUGH
OFFSHORE TO KEEP AREAS OF LOW CLOUDS AND DENSE FOG FROM FORMING OVER
WESTERN SBA COUNTY WHERE A DENSE FOG ADVISORY IS IN EFFECT UNTIL 800
AM. LOW CLOUDS HAVE ALSO FORMED OVER SOUTHERN L.A. COUNTY AND THESE
WILL ALSO LAST UNTIL MID MORNING. YESTERDAYS FAIRLY WARM AIRMASS IS
STILL OVER THE AREA BUT MAX TEMPS WILL BE ABOUT 5 DEGREES COOLER
THAN YDY (BUT STILL ABOVE NORMAL) SINCE HGTS WILL BE FALLING THROUGH
THE DAY AS AN UPPER TROF BEGINS TO MOVE DOWN THE CA/NV BORDER
LOWERING HGTS AND CREATING A MODERATE ONSHORE PUSH TO THE EAST.
WINDS ARE THE MAIN NAME OF THE GAME IN THE SHORT TERM HOWEVER. THIS
AFTERNOON A GOOD NORTH TO NORTHEAST PUSH OF UPPER LEVEL WINDS WILL
MOVE ACROSS THE NORTHERN SECTION OF THE AREA AFFECTED THE MTNS AND
INTERIOR VLYS. GOOD SUBSIDENCE WITH THESE WINDS SHOULD ALLOW FOR
GOOD DOWNWARD TRANSPORT OF THE STRONGER WINDS. ADVISORY LEVELS WIND
GUSTS WILL DEVELOP ACROSS THE MTNS OF SLO AND SBA COUNTY. THE NORTH
WINDS MOVING THROUGH THE SBA MOUNTAINS WILL ALSO SQUIRT OF THE
PASSES AND CANYONS ABOVE THE SBA SOUTH COAST.
ADDITIONALLY...NORTHWEST WINDS WILL DEVELOP ACROSS THE WESTERN
ANTELOPE VALLEY WHERE THERE WILL BE 50 MPH GUSTS. WIND ADVISORIES
NOW COVER THESE AREAS FROM 300PM TO 300AM  THURSDAY. THE WIND GUSTS
WILL INCREASE TO BETWEEN 50 AND 60 MPH IN THE VTA AND LA MTNS. DID
NOT WANT TO CONFUSE THE MSG SO RATHER THAN ADD AN ADVISORY FOR A FEW
HOURS BEFORE THE WARNING JUST MADE THE WARNING START A LITTLE
EARLIER. THESE NORTH WINDS WILL ALSO AFFECT USUALLY CALMER OJAI
VLY/LAKE CASITAS AREA WHICH COULD SEE NORTHERLY GUSTS TO 45 MPH.

THE REAL INTERESTING WEATHER HITS OVERNIGHT WEDNESDAY. THE INSIDE
SLIDER WILL PINCH OFF INTO A CUT OFF LOW AND THEN MIGRATE TO THE
AZ/CA BORDER (GFS) CENTRAL AZ (WRF) OR THE SALTON SEA (EC) THE GFS
SOLN WOULD GENERATE THE STRONGEST WINDS THE EC THE WEAKEST AND THE
WRF SOMEWHERE IN THE MIDDLE. BIG NEWS IS THE COLD AIR ADVECTION THAT
STARTS THIS EVENING AND LASTS INTO THURSDAY MORNING. 850 MB TEMPS
OVER BURBANK DROP 9 DEGREES C DURING THIS PERIOD (15 DEGREES IN THE
24 HOUR PERIOD) SINCE THE COLD AIR IS DENSER THAN THE WARMER AIR IT
REPLACES IT SINKS AND DRAWS DOWN THE FASTER MOVING WINDS ALOFT. THIS
FAST MOVING SINKING AIR WILL BRING 60 MPH WIND GUSTS TO THE COASTS
AND VALLEYS OF VTA AND LA COUNTY...65 MPH GUSTS TO THE SANTA CLARITA
VLY...70 MPH GUSTS TO THE SANTA MONICA MTNS...AND 70 TO 80 MPH GUSTS
TO THE MTNS OF LA AND VTA COUNTY. EARLIER THIS WAS SHAPING UP AS A
NORTHEAST EVENT BUT NOW THE UPPER SUPPORT IS MORE NORTHERLY WHICH
WILL AFFECT THE AREAS IN THE MORE NORTHERLY ORIENTED CANYONS. THUS
THE SAN GABRIEL VLY WHICH IS USUALLY SOMEWHAT SHELTERED FROM THE
SANTA ANAS WILL SEE MUCH STRONGER THAN USUAL GUSTS. LAX WILL ALSO
LIKELY EXPERIENCE STRONG CROSSWINDS.

THURSDAY WILL JUST BE WINDY. THE WINDS WILL RELAX A LITTLE DURING
THE AFTERNOON AND EVENING BUT WILL INCREASE AGAIN OVERNIGHT. THE
UPPER LOW MAY WRAP SOME MID AND HIGH LEVEL CLOUDS INTO THE AREA FOR
PARTLY CLOUDY SKIES. HGTS FALL TO 552 DM AND ALL THE COASTS AND VLYS
WILL SEE MAX TEMPS ONLY IN THE 60S. THIS DESPITE THE AMPLE
COMPRESSIONAL WARMING CREATED BY THE NORTHEAST FLOW.

THE STRONG WINDS AND LOW HUMIDITIES WILL COMBINE TO FORM A DANGEROUS
FIRE GROWTH ENVIRONMENT AND A RED FLAG WARNING IS IN EFFECT FROM 9PM
TONIGTH TO 6 PM FRIDAY.

THE WINDS WILL CALM DOWN OVER PORTIONS OF THE ANTELOPE VLY...CUYAMA
VLY...AND THE INTERIOR SLO VLY. WITH THE COLD AIRMASS IN PLACE MANY
TEMPERATURES WILL DROP TO BELOW FREEZING.

FRIDAY WILL START OF LIKE THURSDAY...WINDY AND COOL. BUT BY
AFTERNOON THE SURFACE GRADIENT RELAXES QUITE A BIT AND WHILE IT WILL
STILL BE BREEZY THE MAX WIND GUSTS WILL FALL INTO THE 40 TO 45 MPH
RANGE AND ALL THE WARNINGS WILL END.

FRIDAY NIGHT THERE WILL BE LESS WIND AND THE SAME COLD AIR MASS IN
PLACE. NOT ONLY WILL THE AREAS THAT SAW FREEZING TEMPS THURSDAY
NIGHT SEE THEM AGAIN BUT THERE WILL ALSO BE SOME FREEZING TEMPS IN
THE OJAI VLY AND INTERIOR PORTIONS OF THE CENTRAL COAST.

.LONG TERM (SAT-TUE)...
A SECOND IMPULSE MOVES OUT OF NEVADA ON SATURDAY. THE GFS USES THIS
ENERGY TO OPEN UP THE CLOSED LOW AND MOVE IT ON EASTWARD. THE EC
TAKES IT AND PINCHES OFF ANOTHER CLOSED LOW AND THEN RETROGRADES IT
OVER SOUTHERN CALIFORNIA WHERE IT SITS AND SPINS FOR 4 DAYS. THE UK
AND CANADIAN ARE BOTH MUCH CLOSER TO THE GFS SOLUTION AND WILL
FOLLOW THE GFS FOR THE EXTENDED FORECAST.

THE GFS KEEPS A COLD AIRMASS OVER THE AREA WITH A HUGE TROF
STRETCHING FROM MINNESOTA TO AZ THIS TROFS ORIENTATION ALLOW FOR
COLD NORTHEAST FLOW IDAHO TO TRAIN OVER THE AREA. OFFSHORE FLOW AT
THE SURFACE WILL KEEP THE AFTERNOON TEMPS A LITTLE HIGHER THAN THEY
WOULD BE OTHERWISE. BUT LOOK FOR MAX TEMPS TO STAY COOL THROUGH THE
PERIOD AND OVERNIGHT LOWS TO BE DOWNRIGHT COLD. IT WILL BE BREEZY
EACH MORNING AND CANNOT RULE OUT THE NEED FOR A FEW WIND ADVISORIES
DURING THIS PERIOD.

THE SYSTEM DOES MOVE OUT TUESDAY AND HOPEFULLY ALLOW FOR SOME
WARMING.

&&

.AVIATION...

30/1140Z

THERE IS A CHANCE THAT THE LIFR CONDS OVER THE CENTRAL COAST WILL
DISSIPATE BEFORE SUNRISE. LIFR CIGS AROUND KLAX AND KLGS WILL LIKELY
LAST UNTIL MID MORNING. A STRONG NORTH TO NORTHEAST WIND EVENT WILL
BEGIN AFTER 08Z.

KLAX...FAIR CONFIDENCE IN THE 12Z TAF. THERE IS A 50 PERCENT OF LIFR
CIGS FROM 12Z TO 15Z. A STRONG CROSSWIND WILL LIKELY DEVELOP AFTER
10Z AND THERE IS A CHANCE SPEEDS COULD INCREASE TO BEYOND THRESHOLDS
AFTER 15Z.

KBUR...HIGH CONFIDENCE IN THE 12Z TAF. LGT-MDT TURBC SFC-080 COULD
DEVELOP AFTER 10Z.

&&

.MARINE...EAST TO NORTHEAST FACING HARBORS...BAYS AND INLETS SUCH AS
AVALON HARBOR MAY BE AFFECTED BY A SHORT PERIOD NORTHEAST WIND
DRIVEN SWELL THURSDAY MORNING THROUGH FRIDAY MORNING. THE SWELL MAY
CREATE HAZARDS FOR BOATERS TRAVELING ACROSS THE INNER WATERS OR
PLANNING TO DOCK OR DROP ANCHOR IN LOCATIONS WITH NORTHEAST EXPOSURE.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING (SEE LAXNPWLOX).
RED FLAG WARNING (SEE LAXRFWLOX).
DENSE FOG ADVISORY (SEE LAXNPWLOX).
WIND ADVISORY (SEE LAXNPWLOX).
GALE WARNING (SEE LAXMWWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).

&&

PUBLIC...RORKE
AVIATION...HALL
SYNOPSIS...B

WWW.WEATHER.GOV/LOSANGELES

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1030 PM PST TUE NOV 29 2011

CAZ034>041-044>046-051>054-059-087-088-547-548-301400-
SAN LUIS OBISPO COUNTY CENTRAL COAST-
SANTA BARBARA COUNTY CENTRAL COAST-SANTA YNEZ VALLEY-
SAN LUIS OBISPO COUNTY INTERIOR VALLEYS-CUYAMA VALLEY-
SANTA BARBARA COUNTY SOUTH COAST-VENTURA COUNTY COAST-
LOS ANGELES COUNTY COAST INCLUDING DOWNTOWN LOS ANGELES-
VENTURA COUNTY INTERIOR VALLEYS-VENTURA COUNTY COASTAL VALLEYS-
SANTA MONICA MOUNTAINS RECREATIONAL AREA-
SAN LUIS OBISPO COUNTY MOUNTAINS-
SANTA BARBARA COUNTY MOUNTAINS-VENTURA COUNTY MOUNTAINS-
LOS ANGELES COUNTY MOUNTAINS EXCLUDING THE SANTA MONICA RANGE-
ANTELOPE VALLEY-CATALINA ISLAND-SANTA CLARITA VALLEY-
LOS ANGELES COUNTY SAN FERNANDO VALLEY-
LOS ANGELES COUNTY SAN GABRIEL VALLEY-
1030 PM PST TUE NOV 29 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWESTERN CALIFORNIA.

.DAY ONE... TODAY

A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE CENTRAL COAST AND
PORTIONS OF SANTA YNEZ VALLEY THROUGH EARLY WEDNESDAY MORNING. FOG
SHOULD LIFT AROUND 8 AM IN THE MORNING.

* DENSE FOG ADVISORY.........SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* HIGH RIP CURRENT RISK......SEE FZUS56 KLOX - SRFLOX FOR DETAILS *

* SPECIAL WEATHER STATEMENT..SEE WWUS86 KLOX - SPSLOX FOR DETAILS *

.DAYS TWO THROUGH SEVEN... WEDNESDAY THROUGH MONDAY

THERE WILL BE A VERY STRONG SANTA ANA WIND EVENT DEVELOPING ACROSS
THE REGION LATE WEDNESDAY OR WEDNESDAY NIGHT...AND CONTINUE INTO
FRIDAY. THERE WILL LIKELY BE DAMAGING WINDS WITH SEVERAL IMPACTS
INCLUDING DOWNED POWERLINES AND TREES...HAZARDOUS DRIVING CONDITIONS
FOR HIGH PROFILE VEHICLES...BLOWING DUST AND SAND AS WELL AS ROUGH
SEAS FOR MARINERS ACROSS THE INNER WATERS. THERE WILL BE DANGEROUS
FIRE CONDITIONS WITH THE POTENTIAL FOR RAPID FIRE GROWTH BEGINNING
WEDNESDAY NIGHT AND CONTINUING THROUGH FRIDAY.

* HIGH WIND WARNING..........SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* RED FLAG WARNING...........SEE WWUS86 KLOX - RFWLOX FOR DETAILS *

* MARINE WEATHER STATEMENT...SEE FZUS76 KLOX - MWSLOX FOR DETAILS *

* SPECIAL WEATHER STATEMENT..SEE WWUS86 KLOX - SPSLOX FOR DETAILS *

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

SIRARD