Area Forecast Discussion
Issued by NWS Los Angeles, CA

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 191031
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
300 AM PDT FRI SEP 19 2014

.SYNOPSIS...
WEAK UPPER LEVEL LOW PRESSURE WILL BRING BELOW NORMAL TEMPERATURES
TO MUCH OF THE REGION THROUGH THE WEEKEND. TEMPERATURES WILL LIKELY
WARM TO NEAR NORMAL EARLY NEXT WEEK AS THE UPPER LOW MOVES EAST AND
HIGH PRESSURE BRIEFLY RETURNS. ANOTHER TROUGH OF LOW PRESSURE MAY
BRING A COOLING TREND FOR THE SECOND HALF OF NEXT WEEK.

&&

.SHORT TERM (TODAY-SUN)...LATEST FOG PRODUCT IMAGERY INDICATED
PLENTY OF LOW LEVEL MOISTURE LINGERING ACROSS COAST AND VALLEYS N OF
POINT CONCEPTION...WHILE LOW CLOUDS WERE MORE RANDOM IN NATURE FOR
AREAS SOUTH OF POINT CONCEPTION. LOW CLOUDS SHOULD FILL IN ACROSS
COAST AND VALLEYS OF LOS ANGELES...VENTURA AND SANTA BARBARA
COUNTIES BY DAWN. THERE WILL BE ENOUGH LOW LEVEL LIFT TO CAUSE SOME
PATCHY DRIZZLE TO OCCUR JUST ABOUT ANYWHERE WEST OF THE MOUNTAINS
THIS MORNING. LATEST ACARS SOUNDING NEAR LAX SHOWED A VERY WEAK
INVERSION IN PLACE WHICH MAKES SENSE WHY CLOUDS ARE NOT MORE UNIFORM
S OF POINT CONCEPTION THIS MORNING. WIND PATTERNS ARE INTERESTING
THIS MORNING. OVER THE COASTAL AREAS INTO LA COUNTY THE FLOW IS
MOSTLY CYCLONIC NW BECOMING SW OVER LA COUNTY. HOWEVER...NORTHERLY
WINDS WERE OCCURRING OVER THE MOUNTAINS AND SAN JOAQUIN VALLEY. THIS
NORTHERLY FLOW WAS CAUSING ADDITIONAL CLOUDS TO PILE UP ALONG THE
NORTHERN SLOPES OF THE LOCAL MOUNTAINS THIS MORNING INCLUDING THE
I-5 CORRIDOR.

SYNOPTICALLY...A CLOSED 578 DM UPPER LOW CURRENTLY OFF THE CENTRAL
COAST WILL DRIFT SLOWLY SOUTH JUST WEST OF POINT CONCEPTION BY THIS
AFTERNOON. THE PROXIMITY OF THE UPPER LOW WILL ALLOW FAVORABLE COOL
CYCLONIC FLOW OVER MOST OF LOS ANGELES...VENTURA AND SANTA BARBARA
COUNTIES TODAY. THERE IS NOT MUCH IN THE WAY OF MOISTURE ASSOCIATED
WITH THE UPPER LOW...BUT THERE WILL BE PLENTY LOW CLOUDS LINGERING
ACROSS THE COAST AND VALLEYS THROUGH THIS MORNING AND INTO THE
AFTERNOON ACROSS MOST COASTAL AREAS. RAP AND NAM-WRF MODELS
INDICATED THAT THERE WOULD BE ENOUGH INSTABILITY AND LIMITED MID
LEVEL MOISTURE TO WARRANT A SLIGHT CHANCE FOR SHOWERS OR
THUNDERSTORMS TO DEVELOP OVER THE VENTURA COUNTY MOUNTAINS AS WELL
AS PORTIONS OF THE SANTA BARBARA COUNTY MOUNTAINS THIS AFTERNOON AND
EVENING HOURS. TEMPERATURES WILL CONTINUE TO TREND COOLER THROUGH
SATURDAY AS THE UPPER LOW MOVES DIRECTLY OVER SBA/VENTURA
COUNTIES SATURDAY AFTERNOON. THERE IS NOT MUCH DIFFLUENCE ASSOCIATED
WITH THE UPPER LOW FOR SATURDAY AND MODELS WERE NOT PICKING UP ON
ANY ADDITIONAL MOISTURE OR CONVECTIVE PARAMETERS ACROSS THE LOCAL
MOUNTAINS. WILL LET LATER SHIFTS LOOK CLOSER TO SEE IF SLIGHT CHANCE
POPS WILL BE NEEDED FOR SAT IN THE LOCAL MTNS ONCE AGAIN.EXPECT HIGH
TEMPS TO BE NEAR OR JUST BELOW NORMAL TODAY AND SATURDAY.

BY SUNDAY...THE UPPER LOW WILL FILL IN AND MOVE NE INTO NEVADA
ALLOWING HEIGHTS AND THICKNESS LVLS TO RISE. THERE WILL BE NIGHT
THROUGH MORNING LOW CLOUDS BUT A QUICKER BURNOFF AND HIGH TEMPS WILL
BE A FEW DEGREES HIGHER...ESPECIALLY ACROSS INTERIOR
LOCATIONS...WITH WARMEST VALLEY LOCATIONS IN THE MID 80S...AND MID
TO UPPER 70S ALONG THE COAST.


.LONG TERM (MON-THU)...BOTH GFS AND ECMWF STAY IN PRETTY GOOD
AGREEMENT OVER THE LONG TERM PERIOD. A WEAK RIDGE WILL BEGIN TO
BUILD OVER BAJA CALIFORNIA WHILE MUCH OF NORTHERN CALIFORNIA REMAIN
UNDER A BROAD UPPER TROUGH THROUGH WED. EXPECT NIGHT THROUGH MORNING
LOW CLOUDS FOR COASTAL AREAS AND POSSIBLY SOME COASTAL VALLEYS
THROUGH WED MORNING. TEMPS WILL CONTINUE TO REBOUND MONDAY AND
TUESDAY WITH HIGHS REACHING THE LOWER 90S ACROSS WARMEST VALLEY
LOCATIONS. FOR WED AND THU...A BROAD UPPER TROUGH WILL BEGIN TO DIG
FARTHER SOUTH. THE GFS IS SHOWING A SHARPER TROUGH WHICH WOULD MEAN
MORE SIGNIFICANT COOLING BY THURSDAY...WHERE THE EUROPEAN MODEL IS
LESS PRONOUNCED. AT THIS POINT HAVE TRENDED HIGH TEMPS DOWN SLIGHTLY
FOR WED...WITH A FEW MORE DEGREES OF COOLING FOR THURSDAY TO
SLIGHTLY BELOW NORMAL FOR THIS TIME OF YEAR.


&&

.AVIATION...WILL BE UPDATED WITH 12Z TAFS.

&&

.MARINE...19/300 AM
GOOD CONFIDENCE IN SCA CONDITIONS ACROSS THE SRN TWO THIRDS OF THE
OUTER WATERS THRU LATE TONIGHT...THOUGH WINDS MAY DROP BELOW
ADVISORY LEVELS FOR A FEW HOURS FROM MID MORNING THRU EARLY
AFTERNOON. THERE IS A 20-30 PERCENT CHANCE OF SCA LEVEL WINDS ACRS
WRN SECTIONS OF THE SBA CHANNEL LATE THIS AFTERNOON THRU THE EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).

&&

$$

PUBLIC...KAPLAN
AVIATION/MARINE...DB
SYNOPSIS...SUKUP

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.