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000 FXUS66 KLOX 141742 AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 1045 AM PDT SUN SEP 14 2008 UPDATED AVIATION SECTION .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...14/1730Z. MARINE LAYER DEPTH FAIRLY UNIFORM THIS MORNING...CURRENTLY AROUND 1800 FEET. MODEL CROSS SECTIONS CONTINUE TO ADVERTISE A WEAKENING OF THE ONSHORE FLOW LATER TONIGHT AND MONDAY...WITH A CORRESPONDING SHARP REDUCTION OF THE MARINE LAYER DEPTH. BY MONDAY MORNING...WOULD EXPECT MARINE LAYER DEPTH TO BE LESS THAN 1000 FEET IN MOST AREAS...BRINGING THE POTENTIAL FOR IFR/LIFR CONDITIONS TO COASTAL TAF LOCATIONS...WITH A MORE RAPID CLEARING TREND EXPECTED MONDAY MORNING. KLAX...WITH SATELLITE IMAGERY SHOWING A SOLID BLANKET OF OVERCAST ACROSS THE LA COASTAL PLAIN...WOULD EXPECT CEILING TO LINGER TO AROUND 21Z AT KLAX. WITH MARINE LAYER DEPTH AROUND 1500 FEET LATER THIS AFTERNOON AND EVENING...THERE WILL BE THE POTENTIAL FOR SOME SEA BREEZE STRATUS. PRETTY GOOD CONFIDENCE THAT A CEILING WILL REDEVELOP OVERNIGHT...WITH TIMING MOST LIKELY BETWEEN 04Z-06Z. AT THIS TIME... APPEARS THAT CEILING HEIGHTS WILL RANGE BETWEEN 300 AND 600 FEET. KBUR...CEILING EXPECTED TO BURN OFF WITHIN NEXT HOUR OR SO...WITH SOME HAZE LINGERING THROUGH EARLY AFTERNOON HOURS. WITH MARINE LAYER BECOMING MORE SHALLOW OVERNIGHT...IT IS LIKELY THAT VFR CONDITIONS WILL PREVAIL FOR REMAINDER OF PERIOD. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXMWWLOX). FIRE WEATHER WATCH (SEE LAXRFWLOX). && $$ PUBLIC...WOFFORD/RORKE AVIATION...HALL WWW.WEATHER.GOV/LOSANGELES