Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 281104
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
326 AM PDT SAT MAR 28 2015

.SYNOPSIS...
A WEAK UPPER LEVEL TROUGH WILL BRING SOME COOLING TO THE REGION THIS
WEEKEND...ALONG WITH AN INCREASE IN NIGHT THROUGH MORNING COASTAL
LOW CLOUDS AND FOG. MINOR DAY TO DAY CHANGES IN THE WEATHER ARE
EXPECTED MONDAY THROUGH WEDNESDAY...WITH SOME NIGHT THROUGH MORNING
LOW CLOUDS AND FOG IN COASTAL AREAS. TEMPERATURES WILL LIKELY REMAIN
ABOVE NORMAL...ALTHOUGH THERE WILL BE SOME COOLING IN THE MOUNTAINS
AND DESERTS. A WARMING TREND IS EXPECTED AT THE END OF THE WEEK...
ESPECIALLY WEST OF THE MOUNTAINS AS LOW LEVEL FLOW TURNS OFFSHORE.

&&

.SHORT TERM (TODAY-MON)...LOW CLOUDS AND FOG HAVE BECOME WIDESPREAD
ON THE CENTRAL COAST AND IN THE SANTA YNEZ VALLEY...AND CLOUDS WERE
BEGINNING TO PUSH INTO THE SALINAS VALLEY. THE MARINE LAYER DEPTH
WAS AROUND 500 FEET. THERE WAS SOME LOCALLY DENSE FOG N OF PT
CONCEPTION...THOUGH NOT WIDESPREAD ENOUGH TO REQUIRE ADVISORIES. S
OF PT CONCEPTION...SKIES WERE CLEAR...ALTHOUGH SOME PATCHY STRATUS
WAS BEGINNING TO FORM JUST OFF THE COAST OF L.A. COUNTY. EXPECT SOME
CLOUDS TO MOVE INTO COASTAL SECTIONS OF L.A. COUNTY BY DAYBREAK.
SKIES SHOULD CLEAR BY MID OR LATE MORNING IN MOST AREAS.

INCREASING ONSHORE GRADIENTS SHOULD HELP BRING SEVERAL DEGREES OF
COOLING TO THE COASTAL PLAIN AND THE VLYS TODAY. HEIGHTS AND
THICKNESSES WILL REMAIN QUITE HIGH...SO MAX TEMPS WILL STILL BE
WELL ABOVE NORMAL...ESPECIALLY IN THE VLYS WHERE THE MARINE
INFLUENCE WILL BE MINIMAL. IN THE MTNS AND DESERTS...MAX TEMPS MAY
ACTUALLY EDGE UPWARD A DEGREE OR TWO.

A WEAK UPPER TROUGH WILL PUSH INTO THE WEST COAST TONIGHT AND
SUNDAY. STRONG NW WINDS ACROSS THE COASTAL WATERS SHOULD HELP SPIN
UP A GOOD EDDY CIRCULATION TONIGHT. THE WRF INDICATES MORE IN THE
WAY OF LOW CLOUDS AND FOG IN COASTAL SECTIONS OF L.A. COUNTY...WITH
CLOUDS LIKELY SPREADING NWD INTO THE VTU COUNTY COAST...AND POSSIBLY
TO SERN SBA COUNTY. CLOUDS MAY ALSO PUSH INTO THE SAN GABRIEL VLY.
FOR NOW...HAVE GONE WITH A FAIR AMOUNT OF LOW CLOUDS ON THE CENTRAL
COAST...BUT THE LATEST WRF SHOWS SOME LOW LEVEL NELY FLOW...SO
CONFIDENCE IN THAT IS NOT GREAT. SKIES SHOULD BECOME MOSTLY SUNNY BY
LATE MORNING. MAX TEMPS WILL LIKELY BE DOWN A BIT MORE ON
SUNDAY...ESPECIALLY IN THE VLYS. HOWEVER...SLIGHT WARMING IS
POSSIBLE ACROSS PORTIONS OF THE CENTRAL COAST IF LOW LEVEL NE WINDS
DEVELOP.

THE UPPER TROUGH WILL MOVE E OF THE REGION SUNDAY NIGHT/MON...AND A
WEAK UPPER RIDGE WILL BUILD INTO THE REGION. ANOTHER GOOD EDDY CRCLN
SHOULD HELP BRING WIDESPREAD CLOUDS TO COASTAL AREAS S OF PT
CONCEPTION...WITH CLOUDS LIKELY SPREADING INTO THE L.A. COUNTY VLYS.
LOW LEVEL NELY FLOW SHOULD BRING A REDUCTION IN THE LOW CLOUDS TO
THE CENTRAL COAST. SLIGHT RISES IN HEIGHTS/THICKNESSES WILL BE
OFFSET BY INCREASING ONSHORE FLOW IN COASTAL AND VLY AREAS S OF PT
CONCEPTION. OVERALL...EXPECT LITTLE CHANGE IN MAX TEMPS IN MOST
AREAS MON.


.LONG TERM (TUE-FRI)...A BROAD TROUGH WILL MOVE INTO THE W COAST
TUE...AND ONSHORE FLOW WILL INCREASE. THIS SHOULD BRING AN INCREASE
IN NIGHT THROUGH MORNING LOW CLOUDS AND FOG...WITH SOME COOLING
IN MOST AREAS. ANOTHER WEAK UPPER TROUGH WILL SWING INTO THE WEST
COAST ON WED...SO EXPECT MOSTLY MINOR CHANGES IN MAX TEMPS...EXCEPT
POSSIBLY ADDITIONAL COOLING IN THE MTNS AND DESERTS.
HEIGHT/THICKNESSES WILL FALL A BIT MORE THU...BUT THE LOW LEVEL FLOW
WILL TURN MORE NLY. THERE SHOULD BE SOME COOLING IN THE MTNS AND
DESERTS...WHILE MAX TEMPS MAY ACTUALLY RISE A BIT IN COASTAL
AND VLY AREAS. LOW LEVEL FLOW IS FCST TO TURN OFFSHORE THU NIGHT AND
FRI. THIS SHOULD BRING ADDITIONAL WARMING TO AREAS W OF THE
MTNS...WITH LITTLE IF ANY NIGHT THROUGH MORNING LOW CLOUDS AND FOG.

&&

.AVIATION...27/1800Z.

MID/UPPER LEVEL TROUGH OF LOW PRESSURE OVER THE EASTERN PACIFIC WILL
APPROACH WHILE A RIDGE OF HIGH PRESSURE OVER THE AREA SHIFTS EAST.
UPPER LEVEL LIGHT SOUTHWEST WINDS WILL BECOME MODERATE SOUTHWEST
AFTER 28/13Z WHILE MID LEVEL LIGHT SOUTH-SOUTHWEST WINDS PREVAIL
OVER THE AREA. MARINE INVERSION WAS NEAR THE SURFACE OVER THE LA
BASIN AND NEAR .5FT ALONG THE CENTRAL COAST. THE LOW LEVEL CLOUD
FIELD WAS OVERCAST WEST AND NORTH OF THE CHANNEL ISLANDS. THE
INVERSION WILL DIFFER BY PLUS .8KFT SATURDAY MORNING AND
BROKEN OVER THE BIGHT. WEAK TO MODERATE ONSHORE PRESSURE
GRADIENT THROUGH 28/04Z AND AFTER 28/19Z OTHERWISE MIXED WEAK
NORTHERLY AND ONSHORE GRADIENT.

MARINE LAYER AT LAX AT 1545Z IS 0 FEET DEEP AND THE INVERSION TOP IS
AT 2601 FEET WITH A TEMP OF 24 DEGREES C.

KLAX...THERE IS A CHANCE VSBY 4SM BR BETWEEN 28/08-28/11Z AND A
CHANCE CIGS 003 AND VSBY 1SM BR BETWEEN 28/11-28/16Z THEN 5-6SM HZ
BETWEEN 28/16-28/20Z.

KBUR...THERE IS A CHANCE CURRENT SKY/VSBY CONDITIONS WILL PERSIST
THROUGH 28/13Z AND A CHANCE VSBY 6SM HZ AFTER 28/13Z.

VIRTUALLY CERTAIN - 95-100%
VERY LIKELY       - 80-95%
LIKELY            - 60-80%
CHANCE            - 30-60%
VERY UNLIKELY     - 20% OR LESS


&&

.MARINE...28/300 AM

THERE IS A GOOD CHANCE SMALL CRAFT ADVISORY CONDITIONS WILL EXIST
FROM POINT PIEDRAS BLANCAS TO POINT SAL 10-60 NM AND FROM POINT SAL
TO SAN CLEMENTE ISLAND TONIGHT THROUGH MONDAY. STRONGEST THROUGH THE
WESTERN PORTIONS. THE STRONGEST NORTHWEST WINDS WILL LIKELY OCCUR
SATURDAY AFTERNOON THROUGH EARLY SUNDAY MORNING WITH LOCAL GUSTS TO
35 KT. THERE IS A 60 PERCENT CHANCE NORTHWEST WINDS WILL INCREASE TO
GALE FORCE NEXT WEEK LATE MONDAY OR EARLY TUESDAY FROM POINT PIEDRAS
TO SAN NICOLAS ISLAND INCLUDING THE WEST HALF OF SANTA BARBARA
CHANNEL. A MIXED SWELL IS LIKELY THROUGH THE WEEKEND...
WEST-NORTHWEST AT 14 SECONDS...SOUTH SWELL AT 19 SECONDS AND LOCALLY
GENERATED NORTHWEST SWELL AT 8 SECONDS. THE COMBINED SEAS FROM POINT
PIEDRAS BLANCAS TO SAN CLEMENTE ISLAND WILL PEAK 10 TO 12 FEET
SATURDAY NIGHT. THE SHORTER PERIOD SEAS WILL SUBSIDE SUNDAY THROUGH
MONDAY MORNING AND IS EXPECTED TO REBUILD TUESDAY WHILE A FRESH
WEST-NORTHWEST SWELL MIXES INTO THE COASTAL WATERS TUESDAY. PATCHY
DENSE FOG...WITH VSBYS BELOW 1 NM WILL AFFECT MUCH OF THE COASTAL
WATERS THROUGH THIS MORNING.

&&

&&

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

&&

$$

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

WWW.WEATHER.GOV/LOSANGELES





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