Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 262120
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
230 PM PDT SUN APR 26 2015

.SYNOPSIS...

GUSTY NORTHERLY WINDS WILL SHIFT TO THE NORTHEAST LATE TONIGHT INTO
MONDAY...BRINGING A WARMING AND DRYING TREND TO THE REGION THROUGH
TUESDAY. THE LAST HALF OF THE WEEK WILL HAVE A COOLING TREND WITH
INCREASING MARINE LAYER CLOUDS AS A LOW APPROACHES.

&&

.SHORT TERM (TONIGHT-WED)...
UPPER LEVEL RIDGE OF HIGH PRESSURE BUILDING ACROSS THE EASTERN
PACIFIC COMBINED WITH WEAKENING ONSHORE FLOW HAS BROUGHT A WARMING
AND DRYING TREND TO SOUTHERN CALIFORNIA TODAY.  TEMPERATURES WILL
CLIMB TO AROUND 80 DEGREES TODAY IN WARMEST VALLEY LOCATIONS.
ANOTHER SURGE OF NORTHERLY WINDS ARE EXPECTED TO PICK UP THIS
EVENING. WIND ADVISORIES POSTED FOR THESE NORTHERLY WINDS INCLUDE THE
SANTA YNEZ MOUNTAINS AND SBA SOUTH COAST...WITH MONTECITO HILLS
LIKELY HAVING THE STRONGEST WINDS WITH GUSTS UP TO 55 MPH. HAVE ALSO
INCLUDED A WIND ADVISORY FOR THIS EVENING FOR THE I-5 CORRIDOR IN THE
LA/VENTURA COUNTY MOUNTAINS ALONG WITH THE SANTA CLARITA VALLEY WHERE
GUSTS BETWEEN 40 AND 50 MPH CAN BE EXPECTED.

THE NORTHERLY WINDS WILL SHIFT TO NORTHEAST AFTER MIDNIGHT ACROSS THE
MOUNTAINS...WITH THE SANTA ANA WINDS THEN DESCENDING INTO THE VALLEYS
AND COASTAL AREAS LATE TONIGHT INTO MONDAY MORNING. THE PROJECTED
OFFSHORE PRESSURE GRADIENT BETWEEN LAX-DAGGETT IS NOT ALL THAT
IMPRESSIVE...FORECASTED TO BE AROUND -3.5 TO -4 MB BY MONDAY
MORNING. HOWEVER...MODELS CONTINUE TO RAMP UP THE UPPER LEVEL WIND
SUPPORT...WITH 850 MB WINDS NOW PROJECTED TO BE AS HIGH AS 50 TO 55
KNOTS ACROSS TYPICAL WIND CORRIDORS IN LA COUNTY. WITH THIS IN
MIND...WIND ADVISORIES HAVE BEEN POSTED FOR MUCH OF LOS ANGELES AND
VENTURA COUNTIES. THE FOCUS OF THE STRONGEST WINDS WILL BE THE LOS
ANGELES COUNTY MOUNTAINS LATE TONIGHT THROUGH MID MORNING MONDAY...
WITH ISOLATED GUSTS AS HIGH AS 60 MPH. COASTAL AND VALLEY AREAS WILL
GENERALLY SEE WIND GUSTS BETWEEN 30 AND 50 MPH. SIGNIFICANT WARMING
AND DRYING WILL TAKE PLACE ON MONDAY WITH THE GUSTY SANTA ANA WINDS.
WARMEST COASTAL/VALLEY LOCATIONS EXPECTED TO CLIMB TO AROUND 90
DEGREES ON MONDAY. THE COMBINATION OF GUSTY SANTA ANA WINDS...LOW
HUMIDITIES...WARM TEMPERATURES...AND DRYING FUELS WILL BRING ELEVATED
FIRE POTENTIAL FOR LOS ANGELES AND VENTURA COUNTIES ON MONDAY. PLEASE
SEE FIRE DISCUSSION BELOW FOR MORE DETAILS.

UPPER LEVEL OFFSHORE WIND SUPPORT WILL WEAKEN SIGNIFICANTLY BY MONDAY
NIGHT...RESULTING IN JUST SOME LIGHT OFFSHORE BREEZES CONTINUING INTO
TUESDAY MORNING. CONTINUED VERY WARM AND DRY CONDITIONS ON TUESDAY. IN
FACT...SOME INTERIOR SECTIONS WILL ACTUALLY BE WARMER ON TUESDAY AS
COMPARED TO MONDAY...ESPECIALLY THE MOUNTAINS AND ANTELOPE VALLEY.
MOST AREAS SHOULD THEN COOL A COUPLE OF DEGREES ON WEDNESDAY.

.LONG TERM (THU-SUN)...
WEAK UPPER LEVEL TROUGH WILL PREVAIL DURING EXTENDED PERIOD...WHICH
WILL HELP TO REINFORCE STRONGER ONSHORE FLOW ALONG WITH A MARINE LAYER
INFLUENCE. INITIALLY...THE LOW CLOUDS AND FOG SHOULD BE CONFINED TO
MOSTLY COASTAL AREAS ON THURSDAY AND FRIDAY MORNING...THEN SPREAD
INLAND INTO THE VALLEYS OVER THE WEEKEND. TEMPERATURES ARE EXPECTED
TO GRADUALLY COOL DURING THE EXTENDED PERIOD.

&&

.AVIATION...26/1800Z.

MID/UPPER LEVEL RIDGE OF HIGH PRESSURE UPSTREAM WILL SHIFT EAST AND
BUILD OVER THE AREA. UPPER LEVEL MODERATE NORTH-NORTHWEST WINDS WILL
BECOME LIGHT NORTH-NORTHWEST AFTER 27/19Z WHILE MID LEVEL MODERATE
NORTH WINDS BECOME LIGHT TO MODERATE NORTHEAST AFTER 27/19Z. MIXED
WEAK TO MODERATE NORTHERLY AND ONSHORE PRESSURE GRADIENT THROUGH
27/04Z THEN WEAK TO MODERATE NORTHEASTERLY GRADIENT BETWEEN
27/04-27/19Z AND WEAK TO MODERATE ONSHORE GRADIENT AFTER 27/19Z.

MARINE LAYER AT LAX AT 1605Z IS 219 FEET DEEP AND THE INVERSION TOP
IS AT 915 FEET WITH A TEMP OF 16 DEGREES C.

KLAX...CURRENT SKY/VSBY CONDITIONS LIKELY THROUGH THE PERIOD. CHANCE
LOW LEVEL WINDS 04014KT APPROXIMATELY 1.5KFT BETWEEN 27/10-27/15Z.

KBUR...VIRTUALLY CERTAIN CURRENT SKY/VSBY CONDITIONS WILL PERSIST
THROUGH THE PERIOD. CHANCE LOW LEVEL WINDS 03025KT APPROXIMATELY
1.9KT AFTER 27/08Z.


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

&&

.MARINE...26/200 PM

IT IS LIKELY NORTHWEST WINDS WILL INCREASE AND GALE FORCE GUSTS WILL
EXIST FROM PIEDRAS BLANCAS TO SAN CLEMENTE ISLAND THROUGH LATE
TONIGHT. SCA CONDITIONS WILL LIKELY EXIST 0-10 NM SLO COUNTY AS WELL
AS IN SANTA BARBARA BASIN TO SAN PEDRO BASIN THIS AFTERNOON THROUGH
LATE TONIGHT. STEEP COMBINED SEAS WILL BUILD TO 9 TO 13 FEET IN THE
OUTER WATERS AND 6 TO 9 FEET IN THE NEAR SHORE BASINS THIS AFTERNOON
AND SUBSIDE MONDAY MORNING. OTHERWISE NORTHWEST WINDS ARE EXPECTED
TO INCREASE TUESDAY AND THERE IS A CHANCE SCA CONDITIONS WILL EXIST
FROM THE VICINITY OF SAN MIGUEL ISLAND TO PIEDRAS BLANCAS TUESDAY
AFTERNOON THROUGH WEDNESDAY EVENING. A LOW PRESSURE SYSTEM MOVING
EAST OVER THE SOUTH PACIFIC AND WAS SOUTHEAST OF NEW ZEALAND THIS
MORNING WILL CONTINUE TO GENERATE STORM FORCE WINDS THROUGH MONDAY
MORNING. THE HIGHEST SEAS WILL PROPAGATE TOWARD SOUTH AMERICA AS THE
WIND FETCH AREA IS ORIENTED WEST-EAST BUT A SOUTH SWELL ORIGINATING
FROM THIS STORM ARE EXPECTED TO ARRIVE SATURDAY.

&&

.FIRE WEATHER...26/1015 AM
NORTHERLY WINDS WILL BE ON THE INCREASE ONCE AGAIN THIS EVENING FOR
THE SBA SOUTH COAST AND SANTA YNEZ RANGE...AS WELL AS THE INTERSTATE
5 CORRIDOR EXTENDING FROM THE LA COUNTY MOUNTAINS SOUTHWARD INTO THE
SANTA CLARITA VALLEY. HUMIDITY VALUES WILL GENERALLY REMAIN ABOVE 30
PERCENT DURING THE EVENING HOURS. WINDS WILL SHIFT TO THE NORTHEAST
AND INCREASE IN SPEED OVERNIGHT INTO MONDAY MORNING. THE STRONGEST
SURGE OF WINDS IN THE LA/VENTURA COUNTY MOUNTAINS IS EXPECTED TO
OCCUR BETWEEN 2 AM AND 10 AM ON MONDAY...WHEN GUSTS BETWEEN 50 AND
60 MPH WILL LIKELY OCCUR. FOR THE VALLEYS AND COASTAL AREAS...THE
STRONGEST WINDS WILL LIKELY OCCUR BETWEEN 4 AM AND NOON...WHEN GUSTS
BETWEEN 30 AND 50 MPH ARE EXPECTED. HUMIDITY VALUES ARE EXPECTED TO
LOWER INTO THE TEENS BY MID TO LATE MORNING ON MONDAY...WITH SOME
SINGLE DIGIT READING BY AFTERNOON. TEMPERATURES WILL CLIMB INTO THE
80S ACROSS MUCH OF THE DISTRICT...WITH WARMEST COASTAL/VALLEY
LOCATIONS AROUND 90 DEGREES. THE COMBINATION OF GUSTY SANTA ANA
WINDS...LOW HUMIDITIES...AND WARM TEMPERATURES...AND DRYING FUELS
WILL BRING ELEVATED FIRE DANGER TO LOS ANGELES AND VENTURA COUNTIES
ON MONDAY. THERE WILL ALSO LIKELY BE A BRIEF PERIOD OF CRITICAL FIRE
WEATHER CONDITIONS FROM MID MORNING MONDAY THROUGH EARLY
AFTERNOON...BUT DURATIONS ARE NOT SUFFICIENTLY LONG TO WARRANT A RED
FLAG WARNING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).
GALE WARNING (SEE LAXMWWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&
$$

PUBLIC...GOMBERG
AVIATION...30
MARINE...30
FIRE...GOMBERG
SYNOPSIS...GOMBERG

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