Area Forecast Discussion
Issued by NWS Los Angeles, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KLOX 220428
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
830 PM PST SUN DEC 21 2014

.SYNOPSIS...
HIGH PRESSURE WILL BRING WARMER AND DRY CONDITIONS TO SOUTHERN
CALIFORNIA MONDAY THROUGH WEDNESDAY. STRONG NORTHERLY WINDS WILL
AFFECT PARTS OF THE REGION TONIGHT...THEN NORTHEAST WINDS WILL
AFFECT VENTURA AND LOS ANGELES COUNTIES MONDAY NIGHT THROUGH
TUESDAY. SLIGHTLY COOLER CONDITIONS ARE EXPECTED FOR CHRISTMAS DAY
INTO THE WEEKEND.

&&

.SHORT TERM (TONIGHT-WED)...
STRONG UPPER LEVEL HIGH PRESSURE SYSTEM BUILDING OFF THE COAST OF SOUTHERN
CALIFORNIA WHILE A BROAD UPPER LEVEL TROUGH SITS OVER THE CENTRAL
PLAINS. IN BETWEEN THESE TWO SYSTEMS...STRONG NORTHERLY FLOW ALOFT
CONTINUES THIS EVENING OVER SOUTHERN CALIFORNIA. THE STRONG FLOW
ALOFT IS EVIDENT BY THE PERSISTENT MOUNTAIN WAVE CLOUD FORMATION
SEEN ON SATELLITE IMAGERY SINCE THIS AFTERNOON. MODEL CROSS SECTIONS
SHOW A DEEP LAYER OF NORTHERLY WINDS (35-50 KNOTS) AND SUBSIDENCE
EXTENDING BETWEEN 850 AND 500 MB LEVEL. IN ADDITION TO THE STRONG
UPPER LEVEL WIND SUPPORT...NORTH-SOUTH PRESSURE GRADIENTS HAVE
TRENDED MORE OFFSHORE DURING THE PAST FEW HOURS. AS OF 8
PM...LAX-BAKERSFIELD WAS AN IMPRESSIVE -7.0 MB WHILE SANTA
BARBARA-BAKERSFIELD WAS -7.1 MB.

WITH THIS KIND OF NORTHERLY WIND EVENT...THE TWO MOST FAVORED AREAS
ARE THE INTERSTATE 5 CORRIDOR IN LOS ANGELES/VENTURA COUNTY
MOUNTAINS AS WELL AS THE SANTA YNEZ RANGE IN THE SANTA BARBARA COUNTY
MOUNTAINS AND SANTA YNEZ RANGE IN SOUTHERN SBA COUNTY. HAVE ALREADY
SEEN SOME IMPRESSIVE WIND REPORTS FROM THESE AREAS WITH WHITAKER
PEAK SHOWING A PEAK WIND GUSTS OF 77 MPH...SANDBERG AND CAMP NINE AT 59
MPH...AND MONTECITO HILLS AT 69 MPH. AS A RESULT...UPGRADED TO HIGH
WIND WARNINGS FOR THE MOUNTAINS OF LOS ANGELES/VENTURA/SBA
COUNTIES...WHERE WIND DAMAGE WILL BE LIKELY. THE MOUNTAIN WAVE WIND
CONDITION HAS ALLOWED SOME OF THESE STRONGER WINDS TO SURFACE AT
LOWER ELEVATIONS AS WELL. WIND ADVISORIES WERE EXPANDED IN COVERAGE
AND NOW INCLUDE MOST OF THE VALLEYS...SANTA MONICA MOUNTAINS...AND
LOS ANGELES COUNTY COAST. DUE TO THE MOUNTAIN WAVE WIND
CONDITION...EVEN LAKE CASITAS HAS SEEN RARE NORTHERLY WINDS...WITH
GUSTS AS HIGH AS 47 MPH. OTHER NOTABLE WIND GUSTS THIS EVENING
INCLUDE PORTER RANCH AT 53 MPH...VAN NUYS AT 41 MPH...GETTY CENTER
AT 49 MPH...AND CHEESEBORO AT 48 MPH. UPPER LEVEL WIND SUPPORT
BEGINS TO WEAKEN LATER TONIGHT...WITH FLOW SHIFTING TO THE
NORTHEAST. THIS SHOULD TRANSLATE INTO WINDS BECOMING SOMEWHAT WEAKER
AND MORE LOCALIZED BY MONDAY MORNING.

*** FROM PREVIOUS DISCUSSION ***

ON MONDAY THE NORTH WINDS WILL TAPER DOWN FAIRLY EARLY IN THE
MORNING. HIGH PRESSURE BUILDS INTO THE NORTHERN ROCKIES WITH A LOW
PRESSURE TROUGH EXTENDING JUST OFF THE CA COAST. THIS OFFSHORE
WEATHER PATTERN SHOULD RESULT IN MORE SUNSHINE AND WARMER
TEMPERATURES FOR VALLEYS AND COASTS...EVEN THE CENTRAL COAST WILL
SEE SIGNIFICANT WARMING ON MONDAY. A SANTA ANA WIND REGIME DEVELOPS
LATE MONDAY AS WINDS TURN NORTHEASTERLY AND OFFSHORE PRESSURE
GRADIENTS BECOME -6 MB LAX-DAG AND -11 MB LAX-TPH. MODELS SHOW
LOW-LEVEL WINDS PEAKING AROUND 45KTS IN THE BEST CORRIDORS OF
EASTERN VENTURA AND WESTERN LOS ANGELES COUNTIES TUESDAY MORNING.
WINDS ABOVE RIDGETOPS ARE NOT ALIGNED ALL THAT WELL AND COLD
ADVECTION LOOKS WEAK AT THIS POINT. ANTICIPATE WE WILL NEED TO
REISSUE SOLID WIND ADVISORIES FOR THE VENTURA AND LOS ANGELES COUNTY
MOUNTAINS AND VALLEYS...AND POSSIBLY INTO COASTAL AREAS FOR LATE
MONDAY NIGHT AND TUESDAY. NOT BEING A VERY COLD SANTA ANA...WE
SHOULD SEE TEMPERATURES CLIMB 10-15 DEGREES BY TUESDAY COMPARED TO
TODAY FOR MANY VALLEYS AND COASTS.

TUESDAY NIGHT AND WEDNESDAY THE SANTA ANA IS MUCH WEAKER WITH LOCAL
ADVISORY LEVEL WINDS IN THE SANTA CLARITA AND VENTURA COUNTY
VALLEYS. PRESSURE GRADIENTS SHOW -5 MB LAX-DAG AND ONLY A -4 MB
LAX-TPH FOR WEDNESDAY MORNING. EXPECT WINDS TO RAPIDLY DECREASE ON
WEDNESDAY WITH TEMPERATURES REMAINING ABOVE NORMAL AND NEARLY AS
WARM AS TUESDAY.

.LONG TERM (THU-SUN)...
RATHER HIGH CONFIDENCE IN A DRY FORECAST FROM CHRISTMAS DAY THROUGH
THE HOLIDAY WEEKEND. A WEAK STORM SYSTEM CROSSES NORTHERN CA ON
THURSDAY BRINGING ADDITIONAL COOLING AND SOME HIGH CLOUDS INTO
SOUTHWEST CA. THE FRONT ASSOCIATED WITH THIS SYSTEM STALLS AND
PUSHES BACK TO THE NORTH LATE ON FRIDAY AND SATURDAY. ADDITIONAL
HIGH CLOUDS COULD MOVE OVER THE REGION AS THE FRONT LIFTS NORTHWARD
AND HIGH PRESSURE REBUILDS ACROSS THE EASTERN PACIFIC OCEAN DURING
THIS TIME FRAME. A FAIRLY AMPLIFIED TROUGH-RIDGE-TROUGH PATTERN IS
SHAPING UP ACROSS THE PACIFIC INTO THE WESTERN U.S. TO END THE YEAR.
THE GFS MODEL IS SHOWING A LOW PRESSURE SYSTEM MAKING AN ATTEMPT TO
UNDERCUT THE HIGH PRESSURE RIDGE TOWARD THE LAST DAY OF THE MONTH.

WE SHOULD SEE WEAK ONSHORE FLOW WITH COOLER TEMPERATURES THURSDAY
THROUGH SUNDAY BUT STILL AT OR ABOVE NORMAL FOR MOST AREAS.

&&

.AVIATION...21/0000Z...

AT 2330Z...THERE WAS A INVERSION BASED AT 2100 FEET WITH A TOP OF
5100 FEET AND A TEMP OF 16 CELSIUS.

OVERALL...MODERATE TO HIGH CONFIDENCE IN 00Z TAF PACKAGE. OVERALL
EXPECT NORTH TO NORTHEAST FLOW TO KEEP LOW CIGS OUT OF MOST
LOCATIONS...EXCEPT FOR KPRB WHERE VLIFR CONDS ARE EXPECTED FROM
10Z-18Z. THE TIMING THERE MAY DIFFER BY 2 HRS FROM TAF TIMES.
LLWS/TURBULENCE EXPECTED FOR KSBA AND KBUR DURING THE EVENING
HOURS...STRONGEST AT KSBA.

KLAX...HIGH CONFIDENCE IN 00Z TAF. MVFR VSBY MAY AFFECT THE AIRFIELD
AT TIMES THROUGH 20Z MONDAY.

KBUR...MODERATE TO HIGH CONFIDENCE IN 00Z TAF. HIGH CONFIDENCE IN
VFR CONDS. MODERATE CONFIDENCE IN WIND FORECAST WITH A 20% CHANCE
THAT LLWS WILL NOT OCCUR.

&&

.MARINE...21/800 PM...

FOR THE OUTER WATERS...GALE FORCE NORTHWEST TO NORTH WINDS WILL CONTINUE
THROUGH MONDAY MORNING FOR ZONES 673/676. THE LARGE NORTHWEST SWELL WILL
CONTINUE TO GRADUALLY SUBSIDE ON MONDAY.

FOR THE INNER WATERS...MODERATE CONFIDENCE IN SMALL CRAFT ADVISORY
LEVEL WINDS THROUGH MONDAY MORNING FOR THE WESTERN HALF OF THE SANTA
BARBARA CHANNEL. LATE MONDAY NIGHT AND TUESDAY...MODERATE OFFSHORE
FLOW IS EXPECTED AND THERE IS MODERATE CONFIDENCE IN SMALL CRAFT
ADVISORY LEVEL WINDS FROM VENTURA SOUTH TO SANTA MONICA.

&&

.BEACHES...21/800 PM...

THE LARGE NORTHWEST SWELL CONTINUES TO SLOWLY DIMINISH THIS
EVENING. FOR THE CENTRAL COAST...STILL EXPECT MARGINAL HIGH SURF
CONDITIONS UNTIL MIDNIGHT...BUT NO COASTAL FLOODING ISSUES.
FOR AREAS SOUTH OF POINT CONCEPTION...WILL EXPECTED CONTINUED
ELEVATED SURF AND DANGEROUS RIP CURRENTS FOR THE WEST FACING BEACHES
OF VENTURA AND LOS ANGELES COUNTIES THROUGH MIDNIGHT.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING (SEE LAXNPWLOX).
WIND ADVISORY (SEE LAXNPWLOX).
GALE WARNING (SEE LAXMWWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH SURF ADVISORY (SEE LAXCFWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).

&&

$$

PUBLIC...GOMBERG/BOLDT
AVIATION/MARINE...SMITH/GOMBERG
SYNOPSIS...BOLDT

WWW.WEATHER.GOV/LOSANGELES













USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.