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000 FXUS66 KLOX 201555 AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 900 AM PDT SAT SEP 20 2008 .SHORT TERM... A TATTERED MARINE INVERSION IS ALL THAT IS LEFT AFTER SOME COLD AIR MOVED OVER THE AREA FROM THE NORTH LAST NIGHT. OTHER THAN A FEW STRANDS OF LOW CLOUDS NEAR THE IMMEDIATE LA AND VTU CO COAST...THE LACK OF A HEALTHY INVERSION HAS KEPT MOST OF THE AREA SOUTH OF POINT CONCEPTION CLEAR. THIS ALL HAS HELPED COOL THINGS OFF THIS MORNING...WITH A SLIGHT CHILL TO THE AIR. TO THE NORTH...THE NORTHERLY FLOW HAS HELPED STRATUS MOVE DOWN THE COAST FROM MONTEREY AND COVER A LARGE PORTION OF INTERIOR SLO CO AND THE CENTRAL COAST. WITH THE WEAK INVERSION...THINGS SHOULD CLEAR OUT FAIRLY QUICKLY. ALTHOUGH THE CLOUD COVERAGE AND WEAK NORTHERLY FLOW HAS HELPED KEEP MORNING MONS UP...THE COOLER AIR ALOFT WILL KEEP TEMPS THE SAME OR COOLER FROM YESTERDAY ACROSS THE ENTIRE REGION. FORECAST TEMPS REFLECT THIS CHANGE AND LOOK GOOD. WIND-WISE...BREEZY CONDITIONS EXPECTED THIS AFTERNOON OVER THE CENTRAL COAST...LA MTNS...AND THE ANTELOPE VALLEY. ALTHOUGH A FEW VERY LOCALIZED SPOTS MAY CLIP ADVISORY THRESHOLDS...THE MAJORITY OF THESE AREAS WILL REMAIN BELOW. ...FROM PREVIOUS DISCUSSION... THE UPPER LOW OVER NRN CA WILL OPEN UP AND LIFT NEWD TODAY...BUT A BROAD UPPER TROUGH WILL LINGER ACROSS THE AREA THROUGH MONDAY WITH WKLY CYCLONIC FLOW ALF. AT THE SFC DECENT LOW LVL N-S GRADS SHOULD CAUSE SOME GUSTY WINDS ACROSS THE CENTRAL COAST AGAIN THIS AFTERNOON...AND WITH GOOD W-E GRADS...STRONG WESTERLY WINDS SHOULD AFFECT THE ANTELOPE VALLEY. THERE WILL BE ANOTHER ROUND OF GUSTY WINDS THRU AND BELOW PASSES AND CANYONS OF SRN SBA COUNTY TONIGHT. IT LOOKS AS THOUGH NWLY FLOW WILL BECOME MORE WDSPRD ACROSS THE MTNS OF L.A./VTU COUNTIES TONIGHT...SO EXPECT LOCALLY STRONG WINDS NEAR THE INTERSTATE 5 CORRIDOR TONIGHT/SUN MORNING. IT LOOKS AS THOUGH WINDS WILL REMAIN BELOW ADVISORY LEVELS IN MOST AREAS. UPSLOPE NLY FLOW SHOULD BRING SOME LOW CLOUDS TO THE NRN SLOPES OF THE L.A/VTU COUNTY MTNS TONIGHT/SUN MORNING. THE WRF SHOWS A STRONGER EDDY CRCLN TONIGHT/SUN MORNING...WITH MORE IN THE WAY OF LOW CLDS/FOG IN CSTL SXNS OF L.A. AND PROBABLY VTU COUNTIES. CLOUDS SHOULD AGAIN BE FAIRLY WDSPRD ON THE CENTRAL COAST AND IN THE SANTA YNEZ/SALINAS VALLEYS. WITH THE EDDY CRCLN...SOME CLOUDS MAY PUSH INTO THE SAN GABRIEL AND POSSIBLY SAN FERNANDO VALLEYS LATE TONIGHT INTO SUN MORNING. WITH LITTLE CHANGE IN HGTS/THICKNESSES ACROSS THE AREA ON SUN...EXPECT LITTLE CHANGE IN MAX TEMPS IN THE MTNS AND DESERTS. ADDITIONAL SLIGHT COOLING AT 950 MB SHOULD BRING SLIGHT COOLING TO COASTAL AND VALLEY AREAS ON SUNDAY. THE WRF SHOWS SOMEWHAT WEAKER N-S GRADS AND NWLY LOW LVL FLOW SUN NIGHT/MON...SO EXPECT LESS IN THE WAY OF WINDS IN THE MTNS AND ACROSS THE SANTA YNEZ RANGE AND THE SBA COUNTY S CST. THERE MAY BE SLIGHTLY DEEPER INLAND PENETRATION OF THE STRATUS SUN NIGHT/MON. WITH HEIGHTS/THICKNESSES BEGINNING TO EDGE UPWARD ON MON...THERE MAY BE A FEW DEGREES OF WARMING IN THE MTNS AND DESERTS...BUT WITH 950 MB TEMPS CHANGING LITTLE...EXPECT LITTLE CHANGE IN BELOW NORMAL MAX TEMPS W OF THE MTNS FOR MON. .LONG TERM...HEIGHTS WILL RISE ACROSS THE AREA TUE AS A FLAT RIDGE BUILDS ALONG THE W CST. AT THE SAME TIME...LOW LVL ONSHORE GRADS WILL WEAKEN. EXPECT THE MARINE LAYER TO BECOME MORE SHALLOW MON NIGHT/TUE...WITH CLOUDS PROBABLY CONFINED TO THE CSTL PLAIN. MAX TEMPS SHOULD BE UP A FEW DEGREES IN MOST AREAS ON TUE...MOST NOTICEABLY IN THE VLYS. MODELS ARE A BIT DIFFERENT WITH THE UPPER PATTERN LATER IN THE WEEK...SPECIFICALLY WITH THE PLACEMENT OF THE UPPER HIGH WHICH IS NOW FCST TO BE SE OF THE FCST AREA AS OPPOSED TO RIGHT OVER THE AREA. HEIGHTS ARE STILL RATHER HIGH...AND MODELS STILL SHOW WEAK OFFSHORE TO NEUTRAL LOW LVL FLOW...AT LEAST WED AND THU MORNINGS. THEREFORE...STILL EXPECT SIGNIFICANT WARMING ON WED... ESPECIALLY IN THE VALLEYS...WHERE TEMPS SHOULD RISE WELL INTO THE 90S IN WARMER LOCATIONS...THEN IT WILL CONT TO BE RATHER WARM THU AND FRI. MARINE LAYER SHOULD BE RATHER MINIMAL IN COVERAGE WED THRU MORNING...CONFINED MAINLY TO AREAS WITHIN A FEW MILES OF THE CST. && .AVIATION...20/1146Z. IFR TO MVFR CONDITIONS ARE SHOWING SOME SIGNS OF SCATTERING OUT AT TERMINALS NORTH OF POINT CONCEPTION. OCCASIONAL MVFR CEILINGS WILL CONTINUE TO OCCUR AT TERMINALS NORTH OF POINT CONCEPTION. IFR CONDITIONS WILL LIKELY REDEVELOP TONIGHT AROUND THE SAME TIME TO LATER THAN LAST NIGHT AT TERMINALS NORTH OF POINT CONCEPTION...WHILE MVFR CONDITIONS WILL LIKELY DEVELOP AFTER 08Z AT LOS ANGELES COUNTY COASTAL TERMINALS. THERE IS A CHANCE OF MVFR CONDITIONS PUSHING INTO KOXR...KBUR...AND KVNY AFTER 11Z TONIGHT. KLAX...VFR CONDITIONS WILL LIKELY PERSIST THROUGH AT LEAST 08Z TONIGHT...WITH A 20 PERCENT CHANCE OF MVFR CEILINGS PUSHING INTO THE KLAX AREA BETWEEN 12Z AND 15Z. AFTER 08Z TONIGHT...THERE IS A 80 PERCENT CHANCE THAT MVFR CONDITIONS WILL DEVELOP...BUT MVFR CONDITIONS COULD NOT ARRIVE UNTIL 11Z. KBUR...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD...EXCEPT FOR A 30 PERCENT CHANCE OF MVFR CONDITIONS AFTER 11Z TONIGHT. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXMWWLOX). && $$ PUBLIC...BRUNO AVIATION...HALL WWW.WEATHER.GOV/LOSANGELES