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000 FXUS66 KLOX 202006 AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 100 PM PDT SAT SEP 20 2008 NEW AVIATION DISCUSSION .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...20/2000Z. AN EDDY WILL SPIN UP A MARINE LAYER TONIGHT...BRINGING LOW CLOUDS AND PATCHY FOG WITH MVFR CONDITIONS TO AT LEAST LA AND VENTURA COUNTY COASTAL SECTIONS. OF GREATER UNCERTAINTY IS WHETHER THE LOW CLOUDS AND FOG WILL ALSO SPREAD TO THE SANTA BARBARA SOUTH COAST AND THE LA COUNTY VALLEY TAF SITES. THE CENTRAL COAST AND KPRB ARE LIKELY TO HAVE LOW CLOUDS AND FOG WITH MVFR CONDITIONS OVERNIGHT. KLAX...FAIR TO GOOD CONFIDENCE IN THE CURRENT TAF. CLEAR SKIES UNTIL 07Z WHEN LOW CLOUDS AND PATCHY FOG WILL ARRIVE WITH MVFR CONDITIONS. A 40 PERCENT CHANCE OF LOW CLOUDS AND FOG ARRIVING AS SOON AS 05Z OR AS LATE AS 09Z. THEN LOW CLOUDS AND FOG UNTIL LATE MORNING SUNDAY. KBUR...LITTLE OR NO CONFIDENCE IN THE TAF FORECAST FOR KBUR. A 50 PERCENT CHANCE OF LOW CLOUDS AND FOG ARRIVING AFTER MIDNIGHT...AND A 50 PERCENT CHANCE OF CLEAR SKIES. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXMWWLOX). && $$ PUBLIC...BRUNO AVIATION...SWEET WWW.WEATHER.GOV/LOSANGELES