Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 270518
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
918 PM PST MON JAN 26 2015

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

LOW PRESSURE WILL CONTINUE TO BRING MAINLY SCATTERED LIGHT
SHOWERS TO THE AREA OVERNIGHT...THEN WEAK HIGH PRESSURE WILL
BUILD IN FOR MIDWEEK AND BRING A DRYING TREND. ANOTHER LOW
PRESSURE IS EXPECTED THURSDAY INTO FRIDAY WITH COOLER TEMPERATURES
AND POSSIBLE LIGHT MOUNTAIN RAIN. A RIDGE OF HIGH PRESSURE SHOULD
BUILD IN OVER THE WEEKEND...WITH POSSIBLE SANTA ANA WINDS AND
WARMER TEMPERATURES.

&&

.UPDATE...

SHOWERS CONTINUE TO STREAM OVER THE SOUTHERN PORTION AREA THIS
EVENING AS A TROUGH OF LOW PRESSURE CENTERED NEAR 32N AND 119W
CONTINUES TO MOVE NORTH OVER THE REGION. MEASURABLE RAINFALL
AMOUNTS HAVE MAINLY OCCURRED OVER LOS ANGELES AND VENTURA COUNTIES
THIS EVENING...WITH A SMALL SWATH OF MEASURABLE PRECIPITATION INTO
EASTERN SANTA BARBARA COUNTY. GENERALLY...TOTALS AROUND 0.10 INCH
HAVE BEEN OBSERVED...WITH TOTALS UP TO 0.50 INCH IN THE SAN
GABRIEL RANGE. TOTALS MAY STILL RISE SLIGHTLY AS THE MAIN SHOWER
BANDS ARE MOVING OVER THE AREA CURRENTLY. CURRENT POPS AND WEATHER
SEEMS AGREEABLE AND NO CHANGE WILL BE MADE.

OF NOTE...A FEW LIGHTNING STRIKES CONTINUE TO OCCUR NEAR THE LOW
CENTER THIS EVENING...BUT ALL MODEL SOLUTIONS SUGGEST THE TROUGHS
COLD POOL REMAINING OFFSHORE OVER THE COASTAL WATERS. A MARINE
WEATHER STATEMENT WAS ADDED FOR THE SOUTHERN OUTER COASTAL
PORTIONS WHERE THE MOST FAVORABLE LIFTED INDEX VALUES ARE PROGGED
TO BE. AT THIS TIME...NO THUNDERSTORMS ARE EXPECTED OVER THE LAND
MASS.

AS THE TROUGH EXITS ON TUESDAY...A SHORTWAVE RIDGE OF HIGH
PRESSURE SANDWICHED WILL BUILD IN OVER THE AREA. THE
RIDGE...LOCATED BETWEEN THE TROUGH IMMEDIATELY OFFSHORE AND THE
TROUGH CENTERED NEAR 24N AND 135W...WILL BUILD IN OVER THE REGION
THROUGH WEDNESDAY AND BRING A DRYING TREND WITH LESS CLOUDS
FOR TUESDAY AND WEDNESDAY.

&&

.PREV DISCUSSION...

SHORT TERM...WEDNESDAY LOOKS DRY WITH A FEW CLOUDS AT TIMES.
LIGHT EASTERLY FLOW WITH A SMALL INCREASE IN OFFSHORE PRESSURE
GRADIENTS WILL SET UP OVER THE REGION...ESPECIALLY OVER THE
CENTRAL COAST. WITH RECOVERING THICKNESS VALUES...THIS SHOULD ADD
UP TO A NICE WARMING TREND TO ABOVE NORMAL BY WEDNESDAY. A VERY
WEAK TROUGH OF LOW PRESSURE WILL STALL OVER CALIFORNIA ON
THURSDAY...BUT WITH CONTINUED WEAK OFFSHORE FLOW AND LITTLE CHANGE
TO THE AIRMASS...TEMPERATURES SHOULD BE ABOUT THE SAME AS
WEDNESDAY.

LONG TERM...THE TROUGH THAT MOVED OVER CALIFORNIA ON THURSDAY
WILL SHIFT OVER TO ARIZONA ON FRIDAY. THE RESULTING NORTHERLY FLOW
HAS SOME MOISTURE TO WORK WITH...WHICH COULD PRODUCE A SHOWER OR
TWO OVER AREAS NORTH OF THE COASTAL RANGE. THE REST OF THE AREA
SHOULD SEE COOLER TEMPERATURES WITH THE COOLER AIR MASS.

THE TROUGH WILL SLOWLY CONTINUE EASTWARD OVER THE WEEKEND...AND TILT
NEGATIVELY ON SATURDAY. WITH BOTH THE GFS AND ECMWF SHOWING
THIS...THERE IS SOME CONFIDENCE IN THIS RARER SOLUTION. THIS WOULD
SET UP A 90 KT NORTHEASTERLY JET...WITH MODERATE NORTHEAST FLOW ALL
THE WAY DOWN THE AIR COLUMN. DESPITE MARGINAL PRESSURE GRADIENTS AT
THE SURFACE...A SOLID SANTA ANA WIND EVENT LOOKS ON TRACK FOR
SATURDAY. THE UPPER LEVEL SUPPORT BREAKS DOWN ON SUNDAY AND MONDAY
AS A SUMMER LIKE RIDGE PUSHES IN. WITH CONTINUED OFFSHORE PRESSURE
GRADIENTS...THE START TO NEXT WEEK LOOKS WARM AND POSSIBLY NEAR
RECORDS.

&&

.AVIATION...27/0515Z.

AT 0515Z AT KLAX... THERE WAS NO INVERSION AT KLAX.

MODERATE CONFIDENCE IN THE 06Z TAFS. FOR AREAS S OF POINT
CONCEPTION...RAIN SHOULD TAPER OFF AFTER 10Z THIS MORNING. 30
PERCENT CHANCE FOR MVFR CIGS THROUGH THE 24 HOUR PERIOD.

AREAS N OF POINT CONCEPTION...RAIN SHOULD CONTINUE THROUGH AROUND
12-14Z THIS MORNING. 30 PERCENT CHANCE OF MVFR CIGS WITH RAIN. 20
PERCENT CHANCE FOR LIFR CIGS NEAR KSMX FROM 10Z TO 16Z THIS MORNING.

KLAX...MODERATE CONFIDENCE IN THE 06Z FORECAST. THERE IS A 30
PERCENT CHANCE OF MVFR CEILINGS OR VISIBILITY RESTRICTIONS. 20
PERCENT CHANCE THAT SHOWERS WILL LINGER UNTIL 14Z THIS MORNING.

KBUR...MODERATE CONFIDENCE IN THE 18Z FORECAST. THERE IS A 30
PERCENT CHANCE OF MVFR CEILINGS OR VISIBILITY RESTRICTIONS. 20
PERCENT CHANCE FOR SHOWERS TO LINGER THROUGH 14Z.

&&

.MARINE...26/900 PM.

AN AREA OF LOW PRESSURE WILL CONTINUE TO MOVE NORTH FROM THE
OFFSHORE COASTAL WATERS INTO THE COASTAL WATERS TONIGHT. MAINLY
ISOLATED TO SCATTERED SHOWERS WILL CONTINUE OVER THE COASTAL
WATERS...BUT AN ISOLATED LIGHTNING STRIKE OR TWO CANNOT BE RULED
OUT THROUGH EARLY TUESDAY MORNING ACROSS THE SOUTHERN OUTER
COASTAL WATERS...MAINLY 30 TO 60NM OFFSHORE.

OTHERWISE...WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT
ADVISORY LEVELS THROUGH THURSDAY.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).

&&

$$

PUBLIC...HALL/KITTELL
AVIATION...CK
MARINE...HALL
SYNOPSIS...B/HALL

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