608 
FXUS66 KLOX 170522
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1015 PM PDT THU OCT 16 2014

UPDATED AVIATION SECTION

.SYNOPSIS...

A TROUGH OF LOW PRESSURE WILL MOVE OVER THE REGION FRIDAY TO
DEEPEN THE MARINE LAYER AND COOL TEMPERATURES THROUGH
SATURDAY...WITH POSSIBLE LIGHT RAIN ON THE CENTRAL COAST. SOME
AREAS OF OVERNIGHT LOW CLOUDS AND FOG...ALONG WITH BELOW NORMAL
TEMPERATURES WILL CONTINUE INTO THE MIDDLE OF NEXT WEEK. THEN...A
WARMUP IS EXPECTED.

&&

.UPDATE...

ONSHORE FLOW REMAINS IN PLACE ACROSS THE AREA THIS EVENING AND IT
SHOULD STRENGTHEN THROUGH FRIDAY AS A BROAD TROUGH OF LOW PRESSURE
NEAR 50 N AND 140 W APPROACHES THE AREA. A COLD FRONT STRETCHING
SOUTH FROM THE TROUGH CENTER TO 30 N AND 135 W WILL APPROACH THE
AREA ON FRIDAY. A COOLING TREND IS EXPECTED AS THE TROUGH
APPROACHES THE REGION. THE MARINE LAYER NEAR 2500 FEET THIS
EVENING SHOULD DEEPEN THROUGH SATURDAY. PATCHY DRIZZLE...THOUGH
UNLIKELY...CANNOT BE RULED COMPLETELY OUT FOR FRIDAY MORNING.

A WEAK INVERSION IN PLACE THIS EVENING WILL MAKE FOR A DIFFICULT
CLOUD FORECAST. ADDED TO THE MIX...THE HIGH LEVEL CLOUDINESS OFF
THE CALIFORNIA COAST WILL PLAY TRICKS ON THE MARINE LAYER STRATUS
BENEATH. A FEW TWEAKS HAVE MADE TO THE PACKAGE TO ADD PARTLY TO
MOSTLY CLOUDY SKIES AREAWIDE. AN UPDATE WILL BE ISSUED SHORTLY.

&&

.PREV DISCUSSION...

SHORT TERM...ON SUNDAY...THE UPPER-LEVEL TROUGH MOVES EAST AND A
WEAK RIDGE BRIEFLY MOVES IN. THIS SHOULD RESULT IN A FEW DEGREES
OF WARMING FOR MOST OF THE AREA.

LONG TERM...LONG RANGE MODELS REMAIN IN FAIRLY GOOD SYNOPTIC
AGREEMENT THROUGH THE MIDDLE OF NEXT WEEK. ANOTHER TROUGH WILL
APPROACH THE REGION ON MONDAY...ONCE AGAIN BRINGING A SLIGHT
CHANCE OF RAIN TO NORTHERN SLO COUNTY SOMETIME BETWEEN MONDAY
AFTERNOON AND TUESDAY MORNING. PRECIP CHANCES ON THE CENTRAL DON'T
LOOK QUITE AS GOOD WITH THIS SYSTEM AS THEY DO WITH THE FRIDAY
NIGHT SYSTEM (NOT THAT THE CHANCES WITH THE FRIDAY NIGHT SYSTEM
ARE VERY GOOD). THE MORE IMPORTANT IMPACT OF THE PASSAGE OF THIS
SYSTEM COULD BE THE OFFSHORE THAT DEVELOPS BY WEDNESDAY OR
THURSDAY. THE GFS AND ECMWF ARE IN GOOD AGREEMENT WITH THE
DEVELOPMENT OF OFFSHORE FLOW FOR BOTH WEDNESDAY AND
THURSDAY...WITH THURSDAY BEING THE BETTER DAY. THE GEM SHOWS SOME
OFFSHORE GRADIENTS ON WEDNESDAY...BUT IS WEAKER ON THURSDAY. THE
GEM ALSO SHOWS A BROAD CYCLONIC FLOW ALOFT STARTING TO DEVELOP ON
THURSDAY...WHILE THE GFS AND ECMWF HAVE A LARGE RIDGE AT 500MB.
CURRENT FORECAST FOLLOWS THE GFS AND ECMWF LATER NEXT WEEK WITH
SOME WARMING FOR WEDNESDAY AND THURSDAY. RIGHT NOW...GOING WITH
HIGHS IN THE UPPER 80S AND LOW 90S FOR THE WARMER VALLEY AREAS ON
THURSDAY.

&&

.AVIATION...17/0520Z.
AT 0450Z AT KLAX...THE BASE OF THE VERY WEAK INVERSION WAS AT
3500 FEET. THE TOP OF THE INVERSION WAS NEAR 6500 FEET WITH A
TEMPERATURE OF 16C.

EXPECT WIDESPREAD MVFR TO DEVELOP IN COASTAL AREAS AFTER 
MIDNIGHT...WITH MAINLY IFR TO LIFR CONDS N OF PT CONCEPTIONS. EXPECT 
STRATUS TO PUSH INTO THE VLYS BY MORNING...WITH MAINLY IFR CONDS 
EXPECTED. SKIES SHOULD CLEAR IN THE VLYS BY MID TO LATE 
MORNING...AND BY AFTERNOON ACROSS THE COASTAL PLAIN. CIGS COULD 
LINGER INTO THE AFTERNOON NEAR THE BEACHES.


KLAX...MODERATE CONFIDENCE IN THE 06Z TAF. THERE IS A 20 PERCENT 
CHANCE CIGS COULD ARRIVE AS EARLY AS 08Z. THERE IS A 20 PERCENT 
CHANCE THAT CIGS COULD LINGER UNTIL AT LEAST 22Z.

KBUR...MODERATE CONFIDENCE IN THE 06Z TAF. THERE IS A 20 TO 30 
PERCENT CHANCE THAT CIGS COULD ARRIVE AS EARLY AS 10Z.


&&

.MARINE...16/900 PM.

LOCAL HAZARDOUS SEAS AROUND 10 FEET WILL PERSIST ACROSS THE OUTER
WATERS LATE THIS EVENING...THEN SUBSIDE. LOCAL GUSTS TO 25 KNOTS WILL
DEVELOP EACH AFTERNOON AND EVENING THROUGH THE WEEKEND BETWEEN
POINT SAL AND AREAS SOUTH TO SAN NICOLAS ISLAND...AND ACROSS THE
WESTERN PORTION OF THE SANTA BARBARA CHANNEL. HAZARDOUS SEAS IN
EXCESS OF 10 FEET COULD DEVELOP AGAIN BETWEEN MONDAY AND WEDNESDAY
ACROSS THE OUTER WATERS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).

&&

$$

PUBLIC...HALL/SUKUP
AVIATION...DB
MARINE...HALL/SIRARD
SYNOPSIS...B/HALL

WWW.WEATHER.GOV/LOSANGELES