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 050959
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
300 AM PDT SAT SEP 5 2015

.SYNOPSIS...

FAIR SKIES THROUGH NEXT WEEK EXCEPT DURING THE OVERNIGHT HOURS WHEN
CLOUDS AND PATCHY FOG WILL BE ALONG THE COAST...AND LOCALLY IN SOME
VALLEYS. THE AFTERNOON TEMPERATURES WILL BE BELOW TO NEAR NORMAL
THROUGH EARLY NEXT WEEK. THEN A CONTINUED WARMING TREND NEXT WEEK
WILL RAISE TEMPERATURES TO ABOVE NORMAL BY MIDWEEK AS HIGH PRESSURE
BUILDS IN.

&&

.SHORT TERM (TODAY-MON)...LOW CLOUD FORECAST WILL BE A TOUGH ONE
THIS MORNING. ALTHOUGH LATEST AMDAR SOUNDINGS NEAR LAX SHOWED THE
MARINE LAYER DEPTH AROUND 3300 FT. THE STRENGTH OF THE INVERSION WAS
NOT TOO STRONG WHICH IS WHY THIS MORNING`S FORECAST WILL BE TRICKY.
LATEST FOG PRODUCT IMAGERY INDICATED WIDESPREAD LOW CLOUD COVERAGE
OVER SAN DIEGO AND ORANGE COUNTY COASTAL AREAS. HOWEVER AREAS TO THE
NORTH WERE STILL CLEAR. THE EDDY CIRCULATION DOES NOT LOOK TO BE AS
STRONG AS YESTERDAY MORNING. WITH A WEAKER INVERSION IN
PLACE...RANDOM CLOUDS COULD DEVELOP JUST ABOUT ANYWHERE WEST OF THE
MOUNTAINS. A FEW CLOUDS HAVE STARTED TO DEVELOP ACROSS THE COASTAL
WATERS FROM CATALINA TO WEST LOS ANGELES. WOULD EXPECT LOW CLOUDS TO
FILL IN ACROSS MUCH OF LA COUNTY BY SUNRISE...BUT NOT AS CONFIDENT
FOR VENTURA COAST AND VALLEYS OR SANTA BARBARA SOUTH COAST.
NEVERTHELESS...WHAT LOW CLOUDS THAT DO FORM SHOULD SCOUR OUT BY LATE
MORNING....TO SUNNY SKIES.

OVERALL...AN UPPER LOW WAS CURRENTLY SWINGING EAST FROM OREGON INTO
IDAHO THIS MORNING. THE ASSOCIATED DEEP TROUGH WILL CONTINUE TO
LINGER OVER THE FORECAST AREA TODAY...BUT AS THE LOW PUSHES
EAST...THE H5 HEIGHTS AND THICKNESS LVLS WILL RISE A FEW DECAMETERS
AND THE ONSHORE FLOW SHOULD BE A TAD WEAKER TODAY. THEREFORE...HIGH
TEMPS SHOULD BE A FEW DEGREES WARMER ACROSS THE BOARD TODAY. HIGHS
WILL REMAIN BELOW NORMAL FOR THIS TIME OF YEAR. THERE WILL CONTINUE
TO BE SOME GUSTY SW WINDS ACROSS THE LA COUNTY MTNS AND FOOTHILLS IN
THE ANTELOPE VALLEY...BUT WELL BELOW ADVISORY LEVELS. TROPICAL STORM
KEVIN WAS LOCATED OVER CENTRAL BAJA BUT IS EXPECTED TO WEAKEN
RAPIDLY TODAY AS IT GETS STEERED BY THE DEEP TROUGH TO THE WEST.
THERE WILL BE NO REMNANT MOISTURE AFFECTING THE FORECAST AREA FROM
KEVIN. FOR TONIGHT INTO SUNDAY...THERE WILL BE WEAK OFFSHORE
GRADIENT SETTING UP BETWEEN NEVADA AND THE SOCAL COAST. WINDS WILL
NOT BE SIGNIFICANT BY ANY MEANS SUNDAY MORNING...BUT THERE WILL BE A
DECENT WARM UP ACROSS THE VALLEYS AND EVEN THE INLAND COASTAL AREAS
OF LA/VTU COUNTIES. THE CENTRAL COAST WILL ALSO SEE A BUMP UP IN
TEMPS SUNDAY AS MODEST DOWNSLOPE OFFSHORE WINDS WILL DEVELOP
SATURDAY NIGHT INTO THE MORNING HOURS. THIS SHOULD HELP THE CENTRAL
COAST HEAT UP INTO THE LOW TO MID 80S FOR SLO AND SANTA MARIA. LOW
CLOUDS WILL BE LIMITED TO LA COUNTY COAST AND POSSIBLY SAN GABRIEL
VALLEY SAT NIGHT INTO SUNDAY MORNING AS WELL. THE OFFSHORE WINDS
WILL QUICKLY REVERT BACK TO ONSHORE YET WEAKLY FOR MONDAY. A RIDGE
OF HIGH PRESSURE ALOFT WILL EXPAND WEST INTO SOUTHERN CALIFORNIA AND
BRING ADDITIONAL WARMING TO THE FORECAST AREA. EXCEPT IT SHOULD BE
COOLER ACROSS THE CENTRAL COAST AS MORE TYPICAL ONSHORE FLOW
PREVAILS WITH HIGH TEMPS DROPPING INTO THE 70S TO AROUND 80.

.LONG TERM (TUE-FRI)... BOTH THE GFS AND ECMWF MODELS ARE IN PRETTY
GOOD AGREEMENT IN RESPECT TO STRENGTHENING THE UPPER RIDGE AS IT
CONTINUES TO EXPAND OVER SOUTHERN CALIFORNIA FROM THE NRN MEXICO.
EXPECT HIGH TEMPS TO BE AROUND NORMAL FOR THIS TIME OF YEAR BY
TUESDAY...WITH MORE WARMING EXPECTED WED INTO THURSDAY. THE MARINE
LAYER WILL RE ESTABLISH ONCE AGAIN ACROSS MOST COASTAL AREAS AND
POSSIBLY INTO THE COASTAL VALLEYS EARLY IN THE PERIOD.

THERE IS A NEW DISTURBANCE OFF THE WEST COAST OF MEXICO THAT HAS A
CHANCE TO GROW INTO A TROPICAL DEPRESSION AND POSSIBLY STRONGER.
MODELS DO PICK UP ON THAT. THE GFS IS THE ONLY MODEL TO KEEP ANY
REMNANT MOISTURE AWAY FROM THE FORECAST AREA. HOWEVER BOTH THE ECMWF
AND CANADIAN MODELS DO DRAW THE POSSIBLE HURRICANE/TROPICAL STORM
REMNANTS OVER THE REGION BY NEXT THURSDAY. STILL TOO EARLY TO JUMP
ON THIS...BUT WILL BE MONITORING OVER THE NEXT SEVERAL DAYS. AT THE
LEAST SOME HIGH TO MID LEVEL CLOUDS MIGHT NEED TO BE ADDED TO THE
FORECAST LATER NEXT WEEK.


&&

.AVIATION...05/0515Z.

AT 2309Z...AT 0440Z THE MARINE INVERSION AT KLAX WAS AROUND 3000
FT...ALTHOUGH THERE WAS ANOTHER VERY WEAK INVERSION AT 1500 FT. THE
TOP OF THE MAIN INVERSION WAS AT 4500 FT WITH A TEMPERATURE OF 18C.

SKIES WERE MOSTLY CLEAR THIS EVENING...BUT EXPECT WIDESPREAD CIGS TO
AFFECT MOST COASTAL AND VALLEY AREAS LATE TONIGHT/SAT MORNING. CONDS
SHOULD BE MOSTLY IN THE MVFR CATEGORY...EXCEPT LOCALLY IFR IN THE
FOOTHILLS AND ON THE CENTRAL COAST. EXPECT SOMEWHAT FASTER CLEARING
OF THE LOW CLOUDS ON SAT MORNING.

KLAX...MODERATE TO HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 20 TO
30 PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 08Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 20 TO
30 PERCENT CHANCE OF IFR CONDS BETWEEN 11Z AND 17Z.

&&

.MARINE...04/800 PM.

SMALL CRAFT ADVISORY CONDITIONS FOR NORTHWEST WINDS ARE EXPECTED TO
PERSIST OVER THE OUTER WATERS...AND NEAR-SHORE NORTH OF POINT SAL.
SEAS OVER THE OUTER WATERS ARE 7 TO 10 FEET...BUT WILL DIMINISH LATE
TONIGHT INTO SATURDAY AS WINDS BEGIN TO SUBSIDE. THE LATEST MODEL
RUNS INDICATE ISOLATED GUSTS TO 25 KNOTS MAINLY OVER THE FAR WESTERN
PORTION OF THE OUTER WATERS ON SATURDAY...POSSIBLY BECOMING MORE
WIDESPREAD SATURDAY EVENING. LOWER TO MODERATE CONFIDENCE IN THIS
FORECAST.

A 20 SECOND PERIOD OR GREATER SOUTH SWELL HAS BEGUN TO BUILD INTO
THE FAR SOUTHERN COASTAL WATERS...AND IS EXPECTED TO BUILD THROUGH
THE WEEKEND TO 3 TO 4 FEET AND THEN PERSIST THROUGH EARLY NEXT WEEK.
THE LONG PERIOD SWELLS WILL LIKELY GENERATE EXTRA SURGING AND
CURRENTS WHICH MAY BE HAZARDOUS TO ANCHORED BOATS.

.BEACHES...BEACHGOERS SHOULD BE AWARE OF POTENTIALLY HAZARDOUS SURF
ALONG EXPOSED SOUTH AND SOUTHWEST FACING SHORES THIS WEEKEND THROUGH
NEXT TUESDAY. A HIGH RISK OF RIP CURRENTS IS EXPECTED TO PERSIST
THROUGH THE WEEKEND...AND MAY BE EXTENDED THROUGH WEDNESDAY.

&&

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

&&

$$

PUBLIC...KAPLAN
AVIATION/MARINE...BRUNO


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.