Issued by NWS Sacramento, CA
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-- Discussion containing changed information from previous version are highlighted. --000 FXUS66 KSTO 221145 AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 345 AM PST SUN NOV 22 2009 .DISCUSSION...-- Changed Discussion --SYSTEM MOVING ACROSS NORTHERN CALIFORNIA EARLY THIS MORNING. SO FAR...RADAR HAS INDICATED MUCH OF THE LIGHT PRECIPITATION ASSOCIATED WITH WARM ADVECTION HAS BEEN LIMITED TO THE NORTHERN SIERRA NEVADA NORTH OF I-80 WITH A LITTLE MORE SUBSTANTIAL PRECIPITATION ASSOCIATED WITH A WEAKENING COLD FRONT OVER NORTHWEST CALIFORNIA. FRONT WILL CONTINUE TO WEAKEN AS IT MOVES SOUTHEAST TODAY AND HEAVIER QPF WILL REMAIN TO THE NORTH OF THE AREA VICINITY OF STRONGER UPPER JET ALONG THE OREGON/CALIFORNIA BORDER. MUCH OF THE PRECIPITATION IS EXPECTED TO TAPER OFF BY MIDDAY AS WEAK LIFT DIMINISHES...THOUGH CROSS-SECTIONS INDICATE QUITE A BIT OF LOW-LEVEL MOISTURE HANGING AROUND UNTIL LATER IN THE DAY. RIDGING SURFACE AND ALOFT BEGINS TO TAKE HOLD TONIGHT AND CONTINUES THROUGH MID-WEEK PROVIDING DRY AND MILD WEATHER FOR THE REGION AS LIGHT TO MODERATE OFFSHORE FLOW DEVELOPS. MEDIUM RANGE MODELS IN SOMEWHAT BETTER AGREEMENT WITH PATTERN LATER IN THE WEEK AS THEY ADVERTISE ANOTHER WEAK SYSTEM DENTING THE RIDGE THANKSGIVING NIGHT INTO FRIDAY BRINGING A CHANCE OF PRECIPITATION TO THE NORTHERN PORTION OF THE FORECAST AREA.-- End Changed Discussion --&& .AVIATION...-- Changed Discussion --WK CDFNT AND UPR TROF WILL MOV ACRS INTR NORCAL TDA FLWD BY HI PRES BLDG INLD TNGT INTO MON. FOR CNTRL VLY...AREAS OF MVFR AND LCL IFR CONDS MNLY N OF I-80 POSS THRU 00Z THEN MNLY VFR AFT EXC AREAS IFR/LIFR IN FOG POSS BTWN 12Z-17Z. FOR FTHLS/MTNS...WDSPRD IFR AND LCL LIFR CONDS...MNLY N OF I-80...WITH CONDS GRDLY IMPVG AFT 03Z MON EXC AREAS IFR/LIFR IN FOG/ST IN MTN VLYS BTWN 11Z-18Z. SN LVLS ARND 045 OVR NRN INTR MTNS...AND 050-060 OVR SIERNEV. LCL SW-NW SFC WND GSTS TO 30 KTS OR GTR OMTNS TIL 04Z MON THEN LCL ELY SFC WND GSTS TO 30 KTS OR GTR OVR SIERNEV AFT 06Z MON TIL ARND 18Z MON.-- End Changed Discussion --&& .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
