000 FXUS66 KLOX 042136 AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 135 PM PST THU DEC 4 2008 .SHORT TERM (TODAY-SUN)...UPPER LOW 500 MILES WEST OF PT CONCEPTION CONTINUES TO RETROGRADE AWAY FROM THE WEST COAST AND IS NO LONGER A FEATURE OF INTEREST. MEANWHILE, A WEAK TROF MOVING THROUGH THE GREAT BASIN TODAY WILL CONTINUE TO MOVE SOUTH TONIGHT. IN ITS WAKE NORTHEAST FLOW ALOFT WILL DEVELOP TONIGHT ALONG WITH DECENT OFFSHORE GRADIENTS. THE COMBINATION OF WHICH WILL RESULT IN A MUCH WARMER DAY AT LOWER ELEVATIONS FRIDAY WITH HIGHS MOSTLY IN THE 70S. WINDS ACROSS VENTURA AND LA COUNTIES ARE NOT EXPECTED TO REACH ADVISORY LEVELS OVER A WIDESPREAD AREA, BUT LOCAL GUSTS UP TO 40 MPH ARE POSSIBLE AT THE USUAL FAVORED LOCATIONS IN THE MOUNTAINS AND UP TO 30 MPH IN THE VALLEYS. OFFSHORE WINDS ALSO EXPECTED TO REACH THE VENTURA COUNTY COASTAL PLAIN. MARINE LYR WILL BE TRICKY TONIGHT AS THERE MAY BE ENOUGH ONSHORE PUSH IN THE EVENING TO GET SOME CLOUDS ACROSS THE COASTAL PLAIN. HOWEVER, WITH OFFSHORE FLOW DEVELOPING AFTER MIDNIGHT ANY CLOUDS THAT DO FORM SHOULD BE PUSHED WESTWARD WITH CLEAR SKIES EXPECTED IN ALL AREAS S OF PT CONCEPTION BY MORNING. N OF PT CONCEPTION, LOW CLOUDS AGAIN EXPECTED TO FILTER INTO INTERIOR SLO COUNTY WITH LIGHT EASTERLY FLOW FROM THE CENTRAL VALLEY. AND PATCHY LOW CLOUDS EXPECTED ALONG THE COAST AS WELL. MODELS NOW SHOWING SOME ENERGY FROM THE GREAT BASIN TROF SPLITTING OFF JUST OFFSHORE FRIDAY. IT`S TOO DRY TO HAVE ANY IMPACT ON OUR AREA, THOUGH DEPENDING ON EXACTLY WHERE IT CUTS OFF IT COULD RESULT IN SLIGHTLY WEAKER OFFSHORE WINDS AND LESS OF A WARMING TREND. OFFSHORE BREEZES WILL DIMINISH LATER FRIDAY WITH VERY LITTLE UPPER SUPPORT AND WEAKER GRADIENTS ON SATURDAY. THIS WILL LEAD TO A LITTLE BIT OF COOLING AT LOWER ELEVATIONS. MEANWHILE, THE AIRMASS AS A WHOLE WILL BE WARMING SLIGHTLY AND THIS WILL LEAD TO WARMER TEMPS IN THE MTNS AND DESERTS. THE UPPER LOW THAT SPLITS OFF JUST TO OUR WEST IS EXPECTED TO BE PULLED INTO THE WESTERLIES SUNDAY. AS IT DOES, ONSHORE FLOW WILL RETURN BRIEFLY, BRINGING FURTHER COOLING TO COASTAL AND VALLEY AREAS. LOW CLOUDS ALSO EXPECTED TO RETURN, ESPECIALLY FOR THE COASTAL ZONES SOUTH OF SBA. .LONG TERM (MON-THU)...CONFIDENCE IN THE EXTENDED IS UNUSUALLY HIGH GIVEN THE VARIOUS CUTOFF LOWS IN OUR PART OF THE WORLD AS THE GFS, ENSEMBLES, AND EURO MODELS ALL IN VERY CLOSE AGREEMENT THROUGH THE MIDDLE OF NEXT WEEK. WHILE THE SUNDAY CUTOFF LOW MOVES EAST OF THE AREA MONDAY, THE OTHER CUTOFF IS EXPECTED TO TAKE A POSITION NEAR 20N/140W. AS THIS HAPPENS, A STRONG HIGH PRESSURE RIDGE WILL DEVELOP IN BETWEEN THEM EARLY NEXT WEEK. THE EC IS A LITTLE COLDER WITH A TROF DROPPING OVER THE TOP OF THE RIDGE AND SOUTH INTO AZ/NM ON TUE. THE IMPACT OF THIS IS BETTER UPPER SUPPORT FOR OFFSHORE FLOW TUE AND WED AND PROBABLY NOT QUITE AS WARM FOR THE COAST AND VALLEY. BOTH THE GFS AND EC INDICATE AT LEAST A MODERATE OFFSHORE GRADIENT DEVELOPING WITH THICKNESS APPROACHING 570. HISTORICAL GUIDANCE GIVEN THE PARAMETERS IN THE MODEL SUGGEST HIGHS IN THE 70S TO LOWER 80S, HOWEVER IF THE THERE ISN`T AS MUCH COLD AIR ADVECTION AS SHOWN BY THE ECMWF THEN HIGHS COULD EASILY GET IN THE MID OR EVEN UPPER 80S, WHICH WOULD BE NEAR OR SLIGHTLY BELOW RECORD LEVELS. FOR NOW I`VE GONE WITH TEMPS IN THE WARMEST AREAS IN THE LOW TO MID 80S WHICH WOULD BE PROBABLY A FEW DEGREES ON THE WARM SIDE IF THE ECMWF ENDS UP VERIFYING CLOSEST. OFFSHORE FLOW WEAKENS AT THE END OF NEXT WEEK RESULTING IN COOLER TEMPS IN ALL AREAS, BUT LONGER RANGE MODELS ARE NOT SHOWING ANY RAIN IN THIS AREA THROUGH AT LEAST NEXT SAT. && .AVIATION...04/1945Z. LOW CLOUDS AND FOG ARE LIKELY TO RETURN TO MANY COASTAL SECTIONS TONIGHT...HOWEVER THERE IS SOME CONSIDERABLE DOUBT AS TO HOW LONG THE MARINE CLOUDS WILL PERSIST OVERNIGHT...RESULTING IN A LOW CONFIDENCE FORECAST. THE CURRENT FORECAST SHOWS SOME KIND OF MARINE INFLUENCE AFFECTING COASTAL TAFS TO VARYING DEGREES...FOLLOWED BY EARLY CLEARING ON FRIDAY...EXCEPT FOR KSBA WHERE IT MAY ACTUALLY REMAIN CLEAR OVERNIGHT. OFFSHORE FLOW WILL AFFECT MANY AREAS FRIDAY MORNING AND FACILITATE AN EARLY CLEARING FOR MANY COASTAL SITES. KLAX...SOME DEGREE OF MARINE INFLUENCE IS EXPECTED TONIGHT...WITH A 50 TO 60 PERCENT CHANCE OF BKN SKIES BEFORE MIDNIGHT AND A 30 TO 40 PERCENT CHANCE OF BKN SKIES AFTER MIDNIGHT. OTHERWISE SKIES WILL BE CLEAR WITH VFR TO MVFR VISIBILITY. KBUR...DO NOT EXPECT A RETURN OF LOW CLOUDS AND FOG TONIGHT...SO THERE IS FAIRLY HIGH CONFIDENCE IN CLEAR SKIES AND GOOD VISIBILITIES THROUGH FRIDAY. && .LOX WATCHES/WARNINGS/ADVISORIES... HIGH SURF ADVISORY (SEE LAXCFWLOX). HIGH RIP CURRENT RISK (SEE LAXSRFLOX). && $$ PUBLIC...WOFFORD AVIATION...SWEET WWW.WEATHER.GOV/LOSANGELES