Small Craft Advisory 30, NWS Los Angeles, CA

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
848 PM PST TUE FEB 28 2012

.SYNOPSIS...

ANOTHER LOW PRESSURE SYSTEM AND COLD FRONT WILL MOVE SOUTH OVER
THE AREA ON WEDNESDAY. THE BEST CHANCE OF ANY PRECIPITATION WILL
OCCUR MAINLY NORTH OF POINT CONCEPTION...AND SOUTH OF THE AREA.
A COOL AIR MASS WILL REMAIN IN PLACE FOR LATE WEEK...BUT OFFSHORE
FLOW ESTABLISHING WILL ALLOW A WARMING AND DRYING TREND TO TAKE
PLACE OVER NEXT WEEKEND.

&&

.UPDATE...

A DENSE HIGH CLOUD SHIELD IS MOVING SOUTH INTO THE AREA THIS
EVENING FROM THE NORTH AS THE NEXT SYSTEM TAKES AIM ON THE REGION.
A COLD FRONT IS JUST STARTING TO ENTER THE NORTH COAST OF
CALIFORNIA AND WILL SLIDE SOUTH THROUGHOUT TONIGHT AND INTO
WEDNESDAY MORNING. WHILE MUCH LESS COLD AIR EXISTS WITH THIS
SYSTEM THAN YESTERDAYS...850 MB MIXING RATIOS ARE WETTER AHEAD OF
THE COLD FRONT IN THE LATEST MODEL SOLUTIONS. NAM-WRF 850 MB
MIXING RATIOS EXCEED 5 G/KG...AND MOISTURE AND OMEGA PROFILES IN
THE NAM AND LOCAL WRF BUFR TIME HEIGHT SECTIONS LOOK DECENT. SKY
AND POPS WILL LIKELY BE TWEAKED HIGHER WITH THE NEXT UPDATE.
THOUGH LOW QPFS ARE EXPECTED NORTH OF POINT CONCEPTION...TIME
HEIGHT SECTIONS APPEAR HEALTHY FOR DECENT SHOT OF PRECIPITATION
FROM DAYBREAK THROUGH THE LATE AFTERNOON HOURS.

AS THE FRONT SLIDES SOUTH ON WEDNESDAY AFTERNOON AND EVENING...THE
FRONT BECOME VERY DISORGANIZED. MOISTURE AND OMEGA PROFILES IN THE
BUFR TIME HEIGHT SECTION BECOME VERY UNFAVORABLE FOR LOS ANGELES
AND VENTURA COUNTIES. FOR AREAS SOUTH OF POINT CONCEPTION...THE
PATTERN WILL BECOME MORE SHOWERY AND LESS STRATIFORM.

WINDS WILL LIKELY PLAY A LARGER FACTOR AS THE EVENT UNFOLDS ON
WEDNESDAY. LOCALLY GUSTY WINDS ARE ALREADY DEVELOPING IN THE
ANTELOPE VALLEY THIS EVENING AS ONSHORE GRADIENTS STRENGTHEN.
ONSHORE FLOW SHOULD INCREASE WEDNESDAY MORNING AND PRODUCE SOME
GUSTY WINDS IN THE FOOTHILL LOCATIONS OF THE ANTELOPE
VALLEY...THEN SPREAD INTO THE VALLEY FLOOR BY WEDNESDAY AFTERNOON.
A WIND ADVISORY IS BEING CONSIDERED FOR THE ANTELOPE VALLEY AT
THIS TIME FOR GUSTY ONSHORE WINDS.

&&

.PREV DISCUSSION...

SHORT TERM...COOL TEMPS AGAIN WED WITH HIGHS MAINLY AROUND 60 AT
LOWER ELEVATIONS AND 40S IN THE MTNS. SNOW LEVEL WILL BE HIGHER
WITH THIS STORM, MOSTLY ABOVE 5000 FEET, AND NOT EXPECTING ANY
IMPACTS ON THE GRAPEVINE. MAYBE AN INCH OR TWO OF ACCUMULATION
POSSIBLE ACROSS THE ERN SAN GABRIELS LATE WEDNESDAY INTO WEDNESDAY
NIGHT.

DRIER NORTHERLY FLOW TO TAKE OVER THURSDAY THEN VEERING TO NORTHEAST
FRIDAY AS A NEW ROUND OF SANTA ANA WINDS DEVELOP GOING INTO THE
WEEKEND. THIS WILL BRING A SLOW WARMING TREND, WITH HIGHS BY FRIDAY
GETTING CLOSE TO 70 AT LOWER ELEVATIONS. COULD SEE SOME ADVISORY
LEVEL NORTH WINDS THROUGH THE SANTA YNEZ RANGE THURSDAY EVENING
BEFORE WINDS SHIFT TO NORTHEAST AND FOCUS TURNS TO LA/VENTURA
COUNTIES ON FRIDAY. AT THIS TIME IT COULD BE A SOLID WIND ADVISORY
DAY FRIDAY FOR THE LA/VTU VALLEYS AND MOUNTAINS, THOUGH SOMETIMES
THE NAM OVERDOES THE OFFSHORE WINDS THIS FAR OUT SO DON'T WANT TO
COMMIT TO ANYTHING YET. THE GFS IS DEFINITELY WEAKER SO WILL HAVE TO
SEE HOW THIS EVOLVES OVER THE NEXT COUPLE DAYS.

LONG TERM...WEAK TO MODERATE OFFSHORE FLOW TO CONTINUE RIGHT ON
THROUGH THE WEEKEND WITH THE WARMER DAYS. SHOULD SEE VALLEY HIGHS
GETTING INTO THE 80S BY SATURDAY AND A COUPLE DEGREES WARMER
SUNDAY. COAST WILL BE COOLER BUT STILL MOSTLY IN THE 70S.

OFFSHORE FLOW TURNS ONSHORE EARLY NEXT WEEK AS THE UPPER RIDGE
BREAKS DOWN AND A COUPLE SYSTEMS PASS WELL TO THE NORTH AND EAST.
SOME FAIRLY SIGNIFICANT DIFFERENCES IN THE MODELS, ESPECIALLY BY THE
MIDDLE AND END OF NEXT WEEK WITH THE GFS/EC ALMOST COMPLETELY OUT OF
PHASE. FOR NOW, TURNING COOLER AFTER THE WEEKEND BUT NO
PRECIPITATION EXPECTED THROUGH MID WEEK.

AVIATION...28/2355Z.

VFR CONDITIONS ARE EXPECTED THROUGHOUT AT LEAST 06Z TONIGHT...THEN
THERE IS A CHANCE OF IFR TO MVFR CONDITIONS AT LOS ANGELES COUNTY
TERMINALS AND AT KPRB. MVFR CONDITIONS WILL DEVELOP AFTER 11Z ALONG
A FRONTAL BOUNDARY IN SHOWERS FROM THE NORTHERN TERMINALS SOUTH TO
KSBA.

KLAX...VFR CONDITIONS WILL LIKELY PERSIST THROUGH AT LEAST 08Z
WEDNESDAY...THEN THERE IS A 40 PERCENT CHANCE OF IFR TO MVFR
CONDITIONS THROUGH 18Z WEDNESDAY. MVFR CONDITIONS ARE POSSIBLE AFTER
20Z WEDNESDAY IN SHOWERS.

KBUR...VFR CONDITIONS WILL LIKELY PERSIST THROUGH AT LEAST 11Z
WEDNESDAY...THEN THERE IS A 30 PERCENT CHANCE OF IFR TO MVFR
CONDITIONS THROUGH 16Z WEDNESDAY. MVFR CONDITIONS ARE POSSIBLE AFTER
20Z WEDNESDAY IN SHOWERS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...FROST ADVISORY FROM 3 AM TO 8 AM PST WEDNESDAY CAZ044.

PACIFIC COASTAL WATERS...NONE.
&&

PUBLIC...HALL

AVIATION...HALL

WWW.WEATHER.GOV/LOSANGELES

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
145 PM PST TUE FEB 28 2012

CAZ034>041-044>046-051>054-059-087-088-547-548-291400-
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-
145 PM PST TUE FEB 28 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWESTERN CALIFORNIA.

.DAY ONE... TODAY AND TONIGHT

AREAS OF FROST WITH TEMPERATURES BETWEEN 28 AND 32 DEGREES ARE
EXPECTED ACROSS PORTIONS OF VENTURA COUNTY LATE TONIGHT.

* FROST ADVISORY.............SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

.DAYS TWO THROUGH SEVEN... WEDNESDAY THROUGH MONDAY

AREAS OF FROST WITH TEMPERATURES BETWEEN 28 AND 32 DEGREES ARE
EXPECTED ACROSS PORTIONS OF VENTURA COUNTY EARLY WEDNESDAY MORNING.
GUSTY NORTHEAST WINDS ARE POSSIBLE ACROSS VENTURA AND LOS ANGELES
COUNTIES FRIDAY THROUGH SUNDAY.

* FROST ADVISORY.............SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

.SPOTTER INFORMATION STATEMENT...

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

WOFFORD