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000 FXUS66 KLOX 191924 AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 1220 PM PDT FRI SEP 19 2008 NEW AVIATION DISCUSSION .SHORT TERM...SKIES WERE CLEAR ACROSS THE ENTIRE AREA THIS MORNING... AND ARE EXPECTED TO REMAIN SO TODAY. UPPER LOW OFF THE COAST OF NRN CA WILL LIFT NEWD AND OPEN UP LATER TODAY AND TONIGHT. THE SRN END OF THE WEAKENING SFC BOUNDARY ASSOCD WITH THIS SYSTEM WILL MOVE THROUGH THE FCST AREA LATER TODAY AND TONIGHT. SOME COOLING AT 850 MB BEHIND THIS BOUNDARY MAY BRING SLIGHT COOLING TO INTERIOR SECTIONS N OF PT CONCEPTION TODAY. WITH LITTLE CHANGE IN 850/950 MB ELSEWHERE...AND ONLY A SLIGHT INCREASE IN ONSHORE GRADS...EXPECT MOSTLY MINOR CHANGES IN MAX TEMPS TODAY COMPARED TO THOSE REACHED THU. LOW LVL NLY GRADS ARE FCST TO INCREASE ACROSS THE CENTRAL COAST LATER TODAY AND TONIGHT...AND THERE WILL SOME DECENT SUBSIDENCE AND A PERIOD OF FAIRLY NW TO NLY WINDS OF UP TO 30 KT ACROSS SRN SBA COUNTY TONIGHT. EXPECT SOME GUSTY WINDS ON THE CENTRAL COAST THIS AFTERNOON...AND THRU AND BELOW PASSES AND CANYONS OF SRN SBA COUNTY TONIGHT. WINDS COULD APCH ADVISORY LEVELS IN THE SANTA YNEZ MTNS AND BELOW ADJACENT PASSES AND CANYONS OF SRN SBA COUNTY TONIGHT. THE WRF IS SHOWS AN EDDY CRCLN TRYING TO DEVELOP LATE TONIGHT...WITH SOME INCREASE IN LOW LVL MOISTURE ACROSS AT LEAST COAST SECTIONS OF L.A. AND POSSIBLY VTU COUNTIES. STILL...DO NOT EXPECT WDSPRD STRATUS TONIGHT/SAT MORNING...AND WHAT OCCURS WILL LIKELY BE CONFINED TO THE L.A. COUNTY COAST. WHILE THICKNESS VALUES CHANGE LITTLE...INCREASING ONSHORE GRADS AND SOME COOLING AT 850 AND 950 MB SHOULD KNOCK A FEW DEGREES OFF MAX TEMPS IN MOST AREAS ON SAT...WITH TEMPS GENERALLY SLIGHTLY BELOW NORMAL ACROSS THE FCST AREA. THERE COULD AGAIN BE SOME LOCALLY GUSTY WINDS THRU AND BELOW PASSES AND CANYONS OF SRN SBA COUNTY SAT NIGHT...BUT THEY ARE NOT EXPECTED TO BE AS STRONG AS ANY UPPER SUPPORT FADES. GUSTY WINDS MAY ALSO AFFECT THE I5 CORRIDOR SAT NIGHT. BROAD CYCLONIC FLOW ALF WILL CONT ACROSS THE AREA SAT NIGHT AND SUNDAY...WITH MINOR CHANGES IN HEIGHTS/THICKNESSES. THERE WILL PROBABLY BE SOMEWHAT MORE IN THE WAY OF NIGHT THRU MORNING LOW CLOUDS AND FOG IN CSTL SXNS OF L.A. AND VTU COUNTIES AND ON THE CENTRAL COAST...AND SOME CLOUDS COULD SPREAD INTO THE SAN GABRIEL VALLEY. THERE COULD BE SOME SLIGHT COOLING ON SUNDAY...ESPECIALLY IN CSTL AND VLY AREAS AS 950 MB TEMPS DROP A BIT MORE. .LONG TERM...THERE WILL BE LITTLE CHANGE IN THE UPPER PATTERN SUN NIGHT AND MONDAY. THE WRF SUGGESTS A MORE WIDESPREAD AND INVASIVE STRATUS FIELD SUN NIGHT/MON MORNING...WITH CLOUDS PROBABLY SPREADING INTO MOST VLY AREAS. WITH THE INCREASED CLOUD COVER...THERE WILL LIKELY BE ADDITIONAL COOLING IN CSTL AND VALLEY AREAS MON. HEIGHTS BEGIN TO RISE ON TUE AS RIDGING AMPLIFIES OFF THE W CST. EXPECT SOME WARMING IN MOST AREAS ON TUE...AND THE MARINE LAYER SHOULD BECOME MORE SHALLOW. AN UPPER HIGH OFF THE CST IS FCST TO MOVE RIGHT OVER THE AREA WED AND LINGER THRU THU. AT THE SAME TIME...LOW LVL ONSHORE GRADS WILL TURN WEAKLY OFFSHORE OR AT LEAST NEUTRAL WED MORNING AND THU MORNING. IF THIS OCCURS...EXPECT A SHARP REDUCTION IN THE STRATUS...WITH CLDS LIKELY CONFINED TO THE CST DURG THE LATE NIGHT THRU MORNING HOURS WED AND THU. SIGNIFICANT WARMING IS EXPECTED WED...ESPECIALLY IN THE VALLEYS AND ACROSS INTERIOR SXNS OF THE CSTL PLAIN...WITH SLIGHT ADDITIONAL WARMING THU AS THICKNESSES EDGE UPWARD. && .AVIATION...19/1915Z. A VERY LOW CONFIDENCE FORECAST FOR THE COASTAL TAFS. A TROUGH ALONG THE WEST COAST WILL DRAG A WEAK FRONT WITH SOME LOW CLOUDS INTO THE COASTAL WATERS LATER TODAY AND TONIGHT. COASTAL TAFS WITH THE GREATEST VULNERABILITY TO LOW CLOUDS AND FOG MAY EXPERIENCE PATCHY LOW CLOUDS AND FOG TONIGHT. THE TIMING OF THE LOW CLOUDS WILL BE VERY DIFFICULT TO PINPOINT...BUT WILL PROBABLY OCCUR EARLY THIS EVENING ON THE CENTRAL COAST AND LATER OR NOT AT ALL SOUTH OF POINT CONCEPTION. VALLEY TAFS ARE EXPECTED TO BE CLEAR THROUGH SATURDAY. KLAX...A 40 PERCENT CHANCE OF LOW CLOUDS AND FOG WITH MVFR CONDITIONS AFTER MIDNIGHT...OTHERWISE MOSTLY CLEAR. KBUR...HIGH CONFIDENCE IN CLEAR SKIES THROUGH SATURDAY. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXMWWLOX). && $$ PUBLIC...BRUNO AVIATION...SWEET WWW.WEATHER.GOV/LOSANGELES