Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 021627
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
925 AM PDT WED SEP 2 2015

.SYNOPSIS...MODERATE ONSHORE FLOW WILL GRADUALLY WEAKEN HEADING INTO
LABOR DAY WEEKEND. AS A RESULT...MORNING CLOUD COVER TO THE WEST OF
THE MOUNTAINS WILL BECOME CONFINED TO THE COASTAL PLAIN...PRIMARILY
SOUTH OF POINT CONCEPTION. BELOW NORMAL TEMPERATURES THROUGH
SATURDAY WILL REBOUND TO NEAR NORMAL VALUES BY EARLY NEXT WEEK.

&&

.SHORT TERM (TODAY-FRI)...A TROUGH WILL CONTINUE ALONG THE WEST
COAST THIS WEEK MAINTAINING A RELATIVELY DEEP MARINE LYR AROUND
2500` AND TEMPERATURES THAT ARE A FEW DEGREES BELOW SEASONAL NORMS.
THUS, MINIMAL CHANGES IN THE DAY TO DAY WEATHER THROUGH FRIDAY.
CLOUDS WILL PUSH INTO THE VALLEYS EACH NIGHT AND CLEAR TO NEAR THE
COAST BY AFTERNOON. HIGH PROBABLY A DEGREE OR TWO COOLER THROUGH
FRIDAY.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (SAT-TUE)... THE GFS AND ECMWF ARE IN A SLIGHT
DISAGREEMENT WITH THE PLACEMENT OF THE UPPER LOW ON SATURDAY. THE
GFS IS SLIGHTLY MORE AGGRESSIVE IN DIGGING THE UPPER LOW INTO
NRN NEVADA...WHILE THE EC MODEL SHOWS THE LOW FILLING IN AS IT PULLS
NE INTO IDAHO. THE GFS 500 MB ENSEMBLE SEEMS TO BE A BIT
INCONSISTENT FROM SATURDAY ON. SO FIGURING THE UPPER LOW WILL BE A
TAD FARTHER NE ON SATURDAY. STILL ADJUSTED HIGH TEMPS DOWN A COUPLE
DEGREES. ONE NOTABLE ISSUE IS THAT ON SUNDAY MORNING...THE GFS IS
INDICATING A DECENT SURFACE OFFSHORE GRADIENT. IF THIS HOLDS
TRUE...THERE WILL BE SIGNIFICANT WARMING ACROSS THE
REGION...ESPECIALLY THE VALLEYS WITH SOME WARMING TO THE
COAST AS WELL. LOW CLOUDS SHOULD BE LIMITED N OF POINT CONCEPTION
WITH ONLY PATCHY LOW CLOUDS FOR THE CENTRAL COAST. TRICKY FORECAST
FOR STRATUS FOR THE LA/VTU COAST AND VALLEY SAT NIGHT INTO SUNDAY
DUE TO THE OFFSHORE TRENDS. FOR MON-TUE...BOTH MODELS ARE OUT OF
SYNC AS THE GFS SHOWS A WEAK UPPER LOW OFF THE CENTRAL CALIF COAST
WHILE THE EC BRINGS IN A WEAK UPPER RIDGE. FOR NOW...HAVE KEPT WHAT
EARLIER SHIFTS HAD... A SLIGHT WARMING TREND THROUGH EARLY NEXT
WEEK.

&&

.AVIATION...02/1145Z.

AT 1107Z...THE MARINE LAYER AT KLAX WAS 3100 FT DEEP. THE TOP OF THE
INVERSION WAS AROUND 5100 FT WITH A TEMPERATURE OF 18 DEG CELSIUS.

WIDESPREAD MVFR CIGS IN ALL COASTAL AND VALLEY AREAS S OF PT
CONCEPTION...WITH IFR TO LIFR CIGS IN THE FOOTHILLS AND
COASTAL SLOPES. N OF PT CONCEPTION PATCHY LOW MVFR TO IFR
CIGS WERE AFFECTING THE CENTRAL COAST. ABOVE THE STRATUS
PLENTY OF MID AND HIGH CLOUDS WILL STREAM ACROSS THE REGION
THIS MORNING. THERE COULD BE A FEW SPRINKLES S OF PT CONCEPTION
THIS MORNING. EXPECT CLEARING OF THE STRATUS TO BE FAIRLY SLOW
TODAY. CIGS MAY LINGER IN SOME AREAS S OF PT CONCEPTION WELL
INTO THE AFTERNOON...ALTHOUGH THEY MAY RISE INTO THE VFR CATEGORY AS
WELL. EXPECT WIDESPREAD STRATUS AGAIN IN MOST COASTAL AREAS
TONIGHT/THU MORNING...WITH MOSTLY MVFR CONDS EXPECTED.

KLAX...MODERATE CONFIDENCE IN THE 12Z TAF. THERE IS A
20 TO 30 PERCENT CHANCE THAT CIGS COULD LINGER THROUGH
THE AFTERNOON.

KBUR...MODERATE CONFIDENCE IN THE 12Z TAF. THERE IS A
20 TO 30 PERCENT CHANCE THAT CIGS COULD LINGER THROUGH THE
AFTERNOON.

&&

.MARINE...02/900 AM.

NORTHWEST WINDS ARE EXPECTED TO INCREASE FROM PIEDRAS BLANCAS TO
NORTH OF SAN NICOLAS ISLAND THURSDAY NIGHT AND THERE IS A CHANCE
SMALL CRAFT ADVISORY CONDITIONS WILL EXIST THURDAY NIGHT THROUGH
SATURDAY.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...MW/KAPLAN
AVIATION/MARINE...DB/30

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