[Printable]
Links in the discussion text will open a (small) new browser window with more information inside.
A more complete Weather Glossary is Available Here
000 FXUS66 KLOX 161620 AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 920 AM PDT TUE SEP 16 2008 .SHORT TERM...SIMI VALLEY PROFILER AND NKX/VBG SOUNDINGS ALL SHOWING WARMING IN THE LOW LVLS TODAY WHICH IS SUPPORTED BY MANY OBSERVATIONS THIS MORNING, ESPECIALLY INLAND. ALTHOUGH SOME OF THIS IS LIKELY DUE TO A SLIGHTLY WARMER START TO THE DAY I THINK THERE IS ENUOGH WARM AIR IN PLACE COMBINED WITH SLIGHTLY STRONGER OFFSHORE FLOW TO KEEP TEMPS AT LEAST AT MONDAY`S LEVELS. UPDATED THE ZONES THIS MORNING TO BUMP UP HIGHS A FEW DEGREES AND TO INCLUDE PARTLY CLOUDY MOST ZONES TODAY DUE TO THE THIN LAYER OF MID LEVEL MOISTURE MOVING OVERHEAD. THE POTENTIAL FOR CONVECTION TODAY APPEARS TO BE LOWER THAN PREVIOUSLY THOUGHT. MOISTURE IS VERY LIMITED AND CONFINED TO A VERY NARROW LAYER. INSTABILITY INDICES AREN`T OVERLY IMPRESSIVE. STILL HOWEVER, PARAMETERS AREN`T DOWN ENOUGH TO CONFIDENTLY REMOVE STORMS FROM THE FORECAST SO WILL LEAVE IN A SLIGHT CHANCE THIS AFTERNOON AND EVENING. ON A PROCEDURAL NOTE, THE LOS ANGELES COUNTY VALLEY ZONE (ZONE 47) HAS BEEN SPLIT INTO TWO ZONES THAT INCLUDE THE SAN FERNANDO VALLEY (ZONE 547) AND SAN GABRIEL VALLEY (ZONE 548). THE UPDATED ZONES THAT WERE ISSUED EARLIER INCLUDE THESE NEW ZONES. ALL FUTURE PUBLIC AND FIRE WEATHER PRODUCTS WILL INCLUDE THE NEW ZONES. ...REMAINDER FROM PREVIOUS DISCUSSION... THE GALE IN THE OUTER WATERS WILL SPIN AN EDDY UP TONIGHT AND THIS WILL BRING LOW CLOUDS TO THE L.A. COAST AND PATCHY CLOUDS TO VENTURA. THERE WILL BE BETTER ONSHORE FLOW AND LOWER HGTS AS WELL AS A DEEPER MARINE LAYER AND ALL AREAS SHOULD COOL EXCEPT THE CENTRAL COAST WHICH WILL REMAIN COOL. THE EDDY CONTINUES TO SPIN WEDNESDAY NIGHT AND THURSDAY BUT A LITTLE NORTH PUSH SHOULD KEEP THE CLOUDS MOSTLY OUT OF THE VLYS (EXCEPT THE SANTA YNEZ) THE NORTH PUSH WILL ALSO BRING ABOUT A WEAK SUNDOWNER AND SOME I-5 CORRIDOR WINDS. THE LOWER HGTS WILL ALSO CONTINUE THE COOLING TREND. .LONG TERM... GFS AND EC IN TOTAL DISAGREEMENT IN THE HANDLING OF AN UPPER LOW THAT MOVES INTO NORTHERN CALIFORNIA LATE THURSDAY. THE EC OPENS IT UP AND MOVES QUICKLY OUT INTO NRN NV WHILE THE GFS DEVELOPS A SLOW MOVING CUT OFF LOW WHICH SPENDS MUCH OF THE EXTENDED PERIOD MEANDERING OVER CALIFORNIA. GFS ENSEMBLES ALSO POINT OUT A VERY CONFUSED PATTERN WITH LITTLE OR NO AGREEMENT IN ANY OF THE PERTURBATIONS. THUS MADE LITTLE IN THE WAY OF CHANGES TO THE EXTENDED PERIOD AND WILL HOPE FOR SOME SORT OF AGREEMENT IN FUTURE RUNS. && .AVIATION... 16/1130Z MARINE LAYER NEAR 400 FEET AND ALL GRADIENTS OFFSHORE. SOUTH OF POINT CONCEPTION THE ONLY AVIATION HAZARD WILL BE LOCAL HZ RESTRICTIONS AROUND DAWN. NORTH OF POINT CONCEPTION LIFR CONDS WILL LAST THROUGH MID MORNING. LOW CLOUDS WILL LIKELY REFORM FROM KLAX TO KNTD LATE TONIGHT. KLAX...HIGH CONFIDENCE IN TAF. A CHANCE OF 5SM HZ AFTER DAWN THROUGH MID MORNING. KBUR...HIGH CONFIDENCE IN CAVU TAF. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXMWWLOX). && $$ PUBLIC...WOFFORD/RORKE AVIATION...BRUNO WWW.WEATHER.GOV/LOSANGELES