000
FXUS66 KLOX 141633
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
914 AM PDT SUN SEP 14 2008

.SHORT TERM (TODAY-TUE)...MARINE LYR HAS DECREASED TO ABOUT 1800 FT
THIS MORNING AS HIGH PRESSURE BUILDS OVER THE STATE. ONSHORE IS ALSO
WEAKER THIS MORNING. THE SIMI VALLEY PROFILER IS SHOWING 5-10
DEGREES OF WARMING ABOVE THE MARINE LYR SO EXPECT FOOTHILLS AND
MOUNTAINS ALONG WITH THE SANTA CLARITA VALLEY TO SEE MUCH WARMER
TEMPS TODAY. THE AMOUNT OF WARMING TODAY WILL DECREASE TOWARDS THE
COAST AND EXPECT LITTLE CHANGE IN TEMPS AT THE BEACHES TODAY WITH
SOME CLOUDS AGAIN LINGERING THROUGH THE AFTERNOON.

NOT TOO MUCH CHANGE IN THE 12Z MODELS FOR MON AND TUE. BOTH THE GFS
AND NAM SHOW GRADIENTS TURNING OFFSHORE MONDAY MORNING, WITH THE
OFFSHORE FLOW STRENGTHENING TUESDAY MORNING. WITH 950 TEMPS EXPECTED
TO BE CLOSE TO 30C COMBINED WITH THE OFFSHORE FLOW TEMPS AT ALL
LOWER ELEVATION LOCATIONS SHOULD SEE IMPRESSIVE GAINS MONDAY AND
AGAIN TUESDAY. MOS GUIDANCE VALUES FOR TUESDAY SEEM WAY TOO LOW
GIVEN THE OFFSHORE FLOW AND CURRENT FORECAST NUMBERS ARE SEVERAL
DEGREES HIGHER. LOCAL TEMPERATURE GUIDANCE EVEN INDICATES HIGHS ON
TUE COULD EVEN BE WARMER THAN CURRENTLY INDICATED IF ALL FACTORS
COME TOGETHER AS CURRENTLY PROJECTED.

12Z MODELS SHOWED A NARROW BAND OF MOISTURE AROUND 700 MB FOR TUE
DUE TO THE INFLUENCE OF THE UPPER LOW OFF NRN CALIFORNIA. HOWEVER,
IT`S STILL VERY DRY AT LOWER LEVELS. NAM DID SHOW LI`S DROPPING
BELOW ZERO TUESDAY AFTERNOON OVER ERN LA COUNTY. FOR NOW HAVE
CONFINED AFTERNOON CLOUDS TO THE INTERIOR PORTION OF THE CWA. IF ANY
CONVECTION DOES DEVELOP IT LOOKS LIKE IT WOULD BE OVER ERN LA
COUNTY. BUT CHANCES ARE TOO LOW TO PUT IN THE FORECAST FOR NOW.

*** LONG TERM FROM PREVIOUS DISCUSSION ***

.LONG TERM...
EC AND GFS IN GOOD AGREEMENT THROUGH SATURDAY AND THEN DIVERGE. GFS
ENSEMBLES POINT TO A LOWER CONFIDENCE FORECAST STARTING FRIDAY BUT
MOST OF THE ENERGY IS WELL NORTH OF US AND NOT TOO SURE HOW MUCH THE
DEVIATIONS WILL AFFECT THE WEATHER DOWN HERE. IN SHORT THERE IS
LIKELY GOING TO BE TROFING THROUGH AT LEAST FRIDAY WITH A PM/AM
CLOUD PATTERN AND TEMPS A LITTLE COOLER THAN NORMAL. A SMALL RIDGE
WILL BUILD IN LATER FRIDAY AND SATURDAY PROBABLY TOO LATE TO AFFECT
THE MARINE LAYER OR COASTAL TEMPS SATURDAY MUCH BUT INLAND TEMPS MAY
RISE A FEW DEGREES SATURDAY.

&&

.AVIATION...14/1325Z.
IFR CONDITIONS WILL LIKELY REMAIN AT MOST TERMINALS THROUGH AT LEAST
16Z THIS MORNING. CLEARING IS STILL EXPECTED TO BE SLIGHTLY QUICKER
WITH VALLEY TERMINALS CLEARING AROUND 16Z AND COASTAL TERMINALS
CLEARING BETWEEN 16Z AND 18Z NORTH...TO 17Z TO 21Z SOUTH. AN EARLY
RETURN OF THE MARINE LAYER IS LIKELY TONIGHT FOR
KLAX...KLGB...KSMX...AND KSBP. OTHERWISE...KPMD AND KWJF WILL REMAIN
VFR THROUGHOUT THE PERIOD.

KLAX...IFR CONDITIONS WILL PERSIST WITH CEILINGS BELOW 1000 FEET
THROUGH AT LEAST 16Z...BUT AS LATE AS 18Z. LOW CONFIDENCE EXISTS IN
THE TIMING OF CLEARING...BUT CLEARING SHOULD BE SLIGHTLY
EARLIER...BETWEEN 19Z AND 21Z. VFR CONDITIONS SHOULD DEVELOP AFTER
21Z AND PERSIST THROUGH AT LEAST 01Z...OR AS LATE AS 04Z WHEN THE
STRATUS LAYER HAS A 70 PERCENT CHANCE OF RETURNING.

KBUR...IFR CONDITIONS HAVE DEVELOPED OVER KBUR AND VICINITY THIS
MORNING. VFR CONDITIONS SHOULD REDEVELOP BETWEEN 16Z AND 17Z THIS
MORNING AND WILL PERSIST THROUGHOUT THE REMAINDER OF THE PERIOD.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
FIRE WEATHER WATCH (SEE LAXRFWLOX).

&&

$$

PUBLIC...WOFFORD/RORKE
AVIATION...HALL

WWW.WEATHER.GOV/LOSANGELES