Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 170522 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1020 PM PDT TUE SEP 16 2014

UPDATED AVIATION DISCUSSION

.SYNOPSIS...

WEAKENING HIGH PRESSURE ALOFT AND AN APPROACHING TROUGH OF LOW
PRESSURE WILL BRING A COOLING TREND TO THE AREA THROUGH FRIDAY. A
DEEP MARINE LAYER AND STRONG ONSHORE SHOULD DEVELOP BY THURSDAY
AND FRIDAY. A WARMING TREND AND OFFSHORE FLOW COULD DEVELOP EARLY
NEXT WEEK AND POSSIBLY BRING A RETURN OF A HEATWAVE FOR THE AREA.

&&

.UPDATE...

EXCESSIVE HEAT WARNINGS HAVE BEEN EXPIRED ACROSS THE AREA THIS
EVENING AS SOUTHWEST FLOW ALOFT INCREASES. EXCEPT FOR KSBA-KSMX
AND KSBA-KBFL SURFACE PRESSURE GRADIENTS...SURFACE PRESSURE
GRADIENTS ARE ALREADY ONSHORE OR TRENDING ONSHORE THIS EVENING. A
COOLER DAY IS SETTING UP FOR WEDNESDAY IF ONSHORE PRESSURE
GRADIENTS REESTABLISH AS PROGGED. THE LATEST NAM-WRF SOLUTIONS
INITIALIZED WELL AND COOL 950 MB TEMPERATURES BY 3-5 DEGREES
CELSIUS BY WEDNESDAY AFTERNOON. TEMPERATURES FOR WEDNESDAY WILL
LIKELY BE COOLED ADDITIONALLY...ESPECIALLY FOR THE COASTAL AND
VALLEY LOCATIONS. DESERT TEMPERATURES WILL LIKELY INCREASE AS
TEMPERATURES STUDIES INDICATE HIGH TEMPERATURES FOR PALMDALE AND
LANCASTER NEAR THE CENTURY MARK FOR WEDNESDAY.

KSBA-KSMX SURFACE PRESSURE GRADIENTS REMAIN NEAR -5 MB THIS
EVENING AND KSBA-KBFL SURFACE PRESSURE GRADIENTS TRENDING STRONGLY
TOWARDS A -6 MB VALUE LATER TONIGHT. THE WIND ADVISORY AND RED
FLAG WARNING MIGHT BE EXTENDED IF CONDITIONS AND WEATHER DATA POINT
TOWARDS THE SUNDOWNER WINDS LINGERING A LITTLE LONGER.

&&

.PREV DISCUSSION...

SHORT TERM...A WEAK COLD FRONT WILL ACCOMPANY THE TROF, PASSING
THROUGH THE AREA THU INTO EARLY FRI. MODELS DO SPIT OUT SOME VERY
LIGHT PRECIP ACROSS NRN SLO COUNTY THU BUT FOR NOW AM GOING TO
KEEP POPS BELOW 15% AND JUST GO WITH AN INCREASE IN CLOUDS TO GO
ALONG WITH THE SIGNIFICANT COOLING. BY FRIDAY MORNING THE MARINE
LYR IS EXPECTED TO BE AS MUCH AS 2500` DEEP. WITH THAT DEEPENING
AND SOME UPPER LEVEL ENERGY WITH THE TROF THERE COULD ACTUALLY BE
SOME DRIZZLE OR VERY LIGHT SHOWERS, ESPECIALLY IN THE FOOTHILLS OF
LA/VENTURA COUNTIES FRIDAY MORNING. FOR NOW HAVE JUST ADDED
DRIZZLE WITH 5-10 POPS ACROSS THE AREA THU NIGHT INTO FRIDAY
MORNING.

LONG TERM (SAT-TUE)...BOTH THE GFS AND ECMWF NOW IN DECENT
AGREEMENT WITH THE UPPER LEVEL PATTERN THIS WEEKEND AND NEXT WEEK.
BOTH SHOW THE LOW FILLING SATURDAY WITH SLIGHT HEIGHT RISES, THEN
THE TROF LIFTING OUT SUNDAY INTO MONDAY, FOLLOWED BY A SUBSTANTIAL
RIDGE BUILDING TUESDAY THROUGH THE END OF NEXT WEEK. SO WE SHOULD
SEE A SLOW WARMING TREND WITH LOWERING MARINE LYR DEPTH OVER THE
WEEKEND WITH HIGHS WARMING BACK TO NEAR NORMAL LEVELS BY SUNDAY.
OFFSHORE FLOW WILL ACCOMPANY THE BUILDING RIDGE TUE INTO WED SO WE
EXPECT TO SEE SIGNIFICANT INCREASES IN HIGH TEMPS FOR ALL AREAS. IF
CURRENT MODEL TRENDS HOLD THE HEAT WAVE COMING FOR THE SECOND HALF
OF NEXT WEEK WOULD EASILY EQUAL THE INTENSITY OF THE CURRENT ONE AND
VERY LIKELY EXCEED IT AS THE GFS SHOWS A SLIGHTLY STRONGER OFFSHORE
COMPONENT COUPLED WITH A STRONGER RIDGE ALOFT AND 950 TEMPS AROUND
37C WHICH IS A FEW DEGREES WARMER THAN WHAT WE`RE SEEING NOW. SO
ENJOY THE COOLER WEATHER COMING THE NEXT 5 OR 6 DAYS BECAUSE NEXT
WEEK COULD BE EVEN WARMER THAN THE LAST FEW DAYS HAVE BEEN.

&&

.FIRE WEATHER...16/900 PM.

GUSTY SUNDOWNER WINDS...LOW HUMIDITIES...AND HOT TEMPERATURES
WILL ALSO BRING CRITICAL FIRE WEATHER CONDITIONS TO THE SANTA
BARBARA COUNTY MOUNTAINS AND SOUTH COAST THROUGH THIS EVENING. THE
STRONGEST WINDS WILL BE FOCUSED ACROSS WESTERN PORTIONS...WHERE
GUSTS UP TO 40 MPH CAN BE EXPECTED. HUMIDITIES ACROSS THE SOUTH
COAST AND SANTA YNEZ RANGE WILL GENERALLY RANGE BETWEEN 15 AND 20
PERCENT IN WIND PRONE AREAS AND FOOTHILLS...WHILE TEMPERATURES
COULD SPIKE UP TO AROUND 100 DEGREES. SUNDOWNER WINDS WILL HAVE
THE POTENTIAL TO BE EVEN MORE WIDESPREAD ON WEDNESDAY AFTERNOON
AND EVENING...BUT CONDITIONS WILL NOT BE QUITE AS HOT OR DRY.

SLIGHT COOLING EXPECTED ACROSS THE REGION ON WEDNESDAY...WITH MORE
SIGNIFICANT COOLING THURSDAY INTO FRIDAY. NEAR NORMAL TEMPERATURES
THROUGH THE WEEKEND...THEN A POTENTIAL FOR ANOTHER ROUND OF HOT
TEMPERATURES ON TUESDAY AND WEDNESDAY.

&&

.AVIATION...17/0520Z.
VLIFR TO LIFR CONDS EXPECTED ON THE CENTRAL COAST AND POSSIBLY
IN THE SANTA YNEZ VALLEY LATER TONIGHT THROUGH MID OR LATE MORNING
WED. OTHERWISE...EXPECT VFR CONDS THROUGH WED EVENING...WITH SOME
MVFR VSBYS POSSIBLE NEAR KLAX AND KLGB. EXPECT WIDESPREAD IFR CONDS
TO RETURN TO COASTAL SECTIONS WED EVENING.

GUSTY WINDS THRU AND BELOW PASSES AND CANYONS OF SRN SBA COUNTY WITH
LLWS AND MDT UDDF NEAR KSBA THROUGH LATE TONIGHT AND AGAIN WED
EVENING.

KLAX...HIGH CONFIDENCE IN THE 06Z TAF. THERE IS 10 TO 20 PERCENT
CHANCE OF IFR CONDS BETWEEN 12Z AND 15Z.

KBUR...VERY HIGH CONFIDENCE IN THE 06Z TAF WITH VFR CONDITIONS
THRU THE PERIOD.

&&

.MARINE...16/900 PM.

HIGH CONFIDENCE IN CURRENT MARINE FORECAST. ADVISORY LEVEL WINDS
ACROSS THE OUTER WATERS THROUGH LATE IN THE WEEK. THE STRONGEST
WINDS WILL BE NEAR POINT CONCEPTION DURING THE MID AFTERNOON TO
EARLY EVENING PERIOD.

THE WESTERN HALF OF THE SANTA BARBARA CHANNEL WILL HAVE NORTHWEST
WIND GUSTS TO 25 TO 35 KNOTS DURING THE NEXT FEW LATE AFTERNOONS
AND EVENINGS RELATED TO SUNDOWNER WINDS OFF THE SANTA BARBARA
COUNTY SOUTH COAST.

&&

.BEACHES...16/900 PM.

THE LONG-PERIOD SOUTHERN HEMISPHERE SWELL WILL LINGER THROUGH
THURSDAY. IT WILL CONTINUE TO BRING ELEVATED SURF ALONG SOUTH
FACING BEACHES AND A SIGNIFICANT AMOUNT OF RIP CURRENT ACTIVITY
THOUGH THESE EFFECTS WILL DIMINISH OVER TIME.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
EXCESSIVE HEAT WARNING (SEE LAXNPWLOX).
RED FLAG WARNING (SEE LAXRFWLOX).
WIND ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).

&&

$$

PUBLIC...HALL/MW
AVIATION...HALL
MARINE/BEACHES...HALL/KJ
FIRE WEATHER...GOMBERG/HALL
SYNOPSIS...HALL

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