Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 200422
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
830 PM PST FRI DEC 19 2014

.SYNOPSIS...

A WEAK COLD FRONT WILL BRING THE CHANCE OF SOME LIGHT SHOWERS OVER
THE CENTRAL COAST TONIGHT. HIGH PRESSURE WILL BUILD OVER THE AREA
THIS WEEKEND TO BRING WARMING TEMPERATURES AND THE POTENTIAL FOR
SOME GUSTY NORTH TO NORTHEAST WINDS AT TIMES THROUGH TUESDAY. COOLER
CONDITIONS ARE ANTICIPATED BY CHRISTMAS DAY AS A SYSTEM DIVES INTO
THE GREAT BASIN.

&&

.SHORT TERM (TONIGHT-MON)...A STRONG AND MOIST ZONAL FLOW IS STREAMING
ACROSS THE PACIFIC INTO THE WEST COAST. AT THE LEADING EDGE OF THIS
FLOW...A WEAK UPPER LEVEL TROUGH AND ASSOCIATED SURFACE FRONT IS
BRINGING LIGHT TO MODERATE RAINFALL ACROSS MONTEREY COUNTY. THE LEADING
EDGE OF MEASURABLE RAINFALL HAS MADE ITS WAY DOWN TO THE
MONTEREY/SAN LUIS OBISPO COUNTY BORDER.  THE WEAKENING TROUGH WILL
SLIDE THROUGH THE FORECAST AREA OVERNIGHT. WHILE THERE IS STILL DESCENT
LOW LEVEL MOISTURE ACROSS THE CENTRAL COAST TONIGHT...THERE IS VIRTUALLY
NO LIFT. AS A RESULT...SLIGHT CHANCE OF SHOWERS STILL LOOKS
REASONABLE FOR AREAS NORTH OF POINT CONCEPTION TONIGHT.

HIGH PRESSURE BEGINS TO BUILD OFF THE COAST OF SOUTHERN CALIFORNIA
ON SATURDAY WITH HEIGHTS RISING. STILL PLENTY OF MID AND HIGH LEVEL
MOISTURE AROUND SO SKIES WILL REMAIN PARTLY TO MOSTLY CLOUDY ON
SATURDAY. EXPECT A WARMUP TO BEGIN WITH THIS BUILDING HIGH AND
WARMING ATMOS...DESPITE THE LINGERING SKY COVER. HIGH PRESSURE
CONTINUES TO BUILD ON SUNDAY TO HELP CONTINUE TO WARM AFTERNOON
TEMPS.  OTHER IMPACT OF THE BUILDING RIDGE WILL BE THE BUILDING
SURFACE HIGH NOSING EASTWARD INTO THE WESTERN GREAT
BASIN...RESULTING IN MODERATE TO STRONG N-S PRESSURE GRADIENTS AND
WINDY CONDITIONS FOR THE SANTA YNEZ...THE SBA SOUTH COAST...AND THE
I-5 CORRIDOR BY SUNDAY NIGHT. IN EVENING UPDATE...HAVE BUMPED UP
WINDS SPEEDS A BIT FOR THESE FAVORED LOCATIONS ON SATURDAY
NIGHT...WITH  GUSTS UP TO 40 MPH LIKELY. BY SUNDAY AFTERNOON AND
SUNDAY NIGHT...UPPER LEVEL NORTHERLY FLOW AND SBA-BFL PRESSURE
GRADIENT ARE ON THE INCREASE...WITH A HIGH PROBABILITY OF WIND
ADVISORIES BEING NEEDED.

*** FROM PREVIOUS DISCUSSION ***

SURFACE FLOW TURNS MORE NORTHEASTERLY ON MONDAY WHEN SFC HIGH
PRESSURE CONTINUES TO BUILD OVER THE GREAT BASIN. TEMPERATURES WILL
CONTINUE TO WARM TO LEVELS WELL ABOVE NORMAL UNDER SUNNY SKIES.
WOULD EXPECT AT LEAST SOME GUSTY NORTHEAST WINDS BELOW PASSES AND
CANYONS MONDAY BUT DON`T EXPECT MUCH WIND DOWN TO THE WESTERN
VALLEYS TO THE COAST. THE OFFSHORE FLOW WILL ALSO HELP TO WARM
COASTAL AREAS NORTH OF POINT CONCEPTION.

.LONG TERM (TUE-FRI)...THE OFFSHORE FLOW CONDITIONS CONTINUE ON
TUESDAY FOR SOME ADDITIONAL WARMING...AND WITH CONTINUED SUNNY
SKIES. LAX-DAG PRESSURE GRADIENTS ARE FORECAST TO BE SLIGHTLY MORE
NEGATIVE THAN MONDAY...WHICH SHOULD RESULT IN AT LEAST BREEZY
CONDITIONS DOWN TO THE WESTERN VALLEYS DOWN TO COASTAL VTU COUNTY.
THEN BY WEDNESDAY THE RIDGE BEGINS TO FLATTEN A BIT AS AN UPPER
LEVEL LOW MOVES INTO COASTAL BRITISH COLUMBIA. TEMPS ON WEDNESDAY
WILL COOL A BIT UNDER THE WEAKENING RIDGE. THE GFS AND ECMWF DIFFER
ON WHAT HAPPENS WITH THE TROUGH AS IT MOVES INTO THE WEST COAST. THE
ECMWF IS MUCH SHARPER...SHOWING IT JUST BRUSHING THE FORECAST AREA
WHEN IT DIVES INTO THE DESERT SOUTHWEST. THE GFS IS SLOWER AND NOT
AS SHARP. AT A MINIMUM WOULD EXPECT WINDY CONDITIONS ACROSS THE
NORTHWEST WIND-PRONE AREAS BUT FOR NOW LEFT ANY CHANCES OF
PRECIPITATION OUT OF THE FORECAST. IF THE TROUGH DIGS A LITTLE
DEEPER...IT COULD RESULT IN SOME PRECIPITATION WEDNESDAY NIGHT. FOR
NOW LEANING MORE TOWARD THE GFS BASED ON ITS PERFORMANCE THUS FAR
THIS WINTER. ADDITIONAL COOLING EXPECTED ON THURSDAY AND JUST A BIT
MORE ON FRIDAY BEHIND THE MIDWEEK TROUGH...BUT DRY.

&&

.AVIATION...19/2345Z.

MARINE LAYER AT LAX AT 2340Z IS NONE.

WEAKENING FRONT WILL BRING A CHANCE OF SHOWERS WITH MVFR CIGS TO SLO
COUNTY THIS EVENING...THEN A GOOD CHANCE OF IFR/LIFR CIGS AT KSBP
AND KPRB LATE. OTHERWISE  EXPECTING VFR CIGS ACROSS REMAINDER OF
AIRFIELDS AS WEAK FRONT SLOWLY DRAGS ACROSS THE REGION.

KLAX...MID AND HIGH LEVEL CLOUDS CONTINUE TONIGHT. THERE IS A CHANCE
OF MVFR CIGS/VSBYS LATE TONIGHT AND EARLY SATURDAY MORNING.

KBUR...MID AND HIGH LEVEL CLOUDS CONTINUE TONIGHT. THERE IS A CHANCE
OF MVFR CIGS/VSBYS LATE TONIGHT AND EARLY SATURDAY MORNING.

&&

.MARINE...19/800 PM.

LARGE NORTHWEST SWELL WILL SPREAD SOUTHEASTWARD ACROSS THE OUTER
COASTAL WATERS TONIGHT...PEAKING ON SATURDAY. THE SWELL DIRECTION
IS 290-300 DEGREES...BUT THE LONG PERIOD SHOULD ENABLE SOME OF THIS
SWELL ENERGY TO SPREAD INTO THE INNER WATERS LATE TONIGHT INTO
SATURDAY. SMALL CRAFT FOR HAZARDOUS SEAS WILL BE IN EFFECT FOR THE
OUTER COASTAL WATERS AND NEARSHORE WATERS FROM POINT PIEDRAS BLANCAS TO
POINT SAL...WITH PEAK SWELL HEIGHTS RANGING BETWEEN 13 AND 17 FEET.
MARINE WEATHER STATEMENT WAS ISSUED FOR THIS LARGE SWELL ENERGY...
HIGHLIGHTING POTENTIAL OF DANGEROUS BREAKING WAVES AT MORRO BAY
HARBOR. NORTHWEST WINDS WILL BE ON THE INCREASE THIS WEEKEND ACROSS
THE OUTER WATERS...POTENTIALLY REACHING GALE FORCE BY EARLY SUNDAY
EVENING.

&&

.BEACHES...19/800 PM.

LARGE AND POTENTIALLY DAMAGING SURF EVENT FOR THE CENTRAL COAST THIS
WEEKEND. AS OF 8 PM...LEADING EDGE OF LONG PERIOD SWELL (20 SECOND
PERIOD) HAS ARRIVED TO MONTEREY BUOY...AND WILL CONTINUE TO SPREAD
DOWN THE CENTRAL COAST AND BUILD RAPIDLY OVERNIGHT. SURF STILL
EXPECTED
TO PEAK ON SATURDAY ACROSS THE CENTRAL COAST...WHEN BREAKERS OF 15
TO 20 FEET WILL BE COMMON ACROSS NORTHWEST FACING SHORES. LOCALLY HIGHER
SETS WILL BE LIKELY AT FAVORED LOCATIONS. SOME OF THE POTENTIAL IMPACTS
FOR THE CENTRAL COAST BEACHES INCLUDE SIGNIFICANT BEACH EROSION AND
STRUCTURE DAMAGE. DUE TO THE UNUSUALLY HIGH TIDES THIS
WEEKEND...THERE WILL ALSO LIKELY BE SOME MINOR COASTAL FLOODING OF
LOW LYING AREAS...NEAR TIMES OF THE MORNING HIGH TIDE.

WHILE THE SWELL DIRECTION WITH THIS EVENT IS 290-300 DEGREES...THE
PERIOD SHOULD BE SUFFICIENTLY LONG (18 SECONDS) TO ALLOW SOME OF THE
SWELL ENERGY TO REFRACT INTO THE INNER WATERS. AS A RESULT...HIGH
SURF ADVISORIES HAVE BEEN POSTED FOR WEST FACING BEACHES OF LOS
ANGELES AND VENTURA COUNTIES THIS WEEKEND...WHERE SETS OF 5 TO 8 FEET
CAN BE EXPECTED. LOCAL MAX SETS TO 10 FEET ARE PROJECTED FOR VENTURA
HARBOR. THE LARGE SURF WILL ALSO BRING DANGEROUS RIP CURRENTS TO THE
REGION THIS WEEKEND.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
COASTAL FLOOD WARNING (SEE LAXCFWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH SURF ADVISORY (SEE LAXCFWLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
GALE WATCH (SEE LAXMWWLOX).

&&

$$

PUBLIC...GOMBERG/JACKSON
AVIATION/MARINE/BEACHES...GOMBERG
SYNOPSIS...RAT

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