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AREA FORECAST DISCUSSION

 
 FXUS66 KSTO 241717
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 915 AM PST TUE NOV 24 2009
 
 .DISCUSSION...
 HIGH PRESSURE CONTINUES TO DOMINATE OVER INTERIOR NORTHERN 
 CALIFORNIA BRINGING DRY AND MILD WEATHER. DECOUPLING OF THE BOUNDARY 
 LAYER OVERNIGHT ALLOWED PATCHY DENSE FOG TO DEVELOP THIS 
 MORNING...PRIMARILY IN THE SOUTHERN SACRAMENTO AND NORTHERN SAN 
 JOAQUIN VALLEYS AND NEAR THE DELTA. THIS FOG WILL SLOWLY DISPERSE 
 THROUGH LATE MORNING AS WE START TO SEE MORE DAYTIME HEATING. 
 
 BESIDE THE EARLY MORNING FOG/STRATUS...EXPECT PLENTY OF WARMING THIS 
 AFTERNOON UNDER MOSTLY SUNNY SKIES. TEMPERATURES THIS AFTERNOON 
 SHOULD WARM INTO THE 60S FOR MOST VALLEY LOCATIONS WITH A FEW 
 ISOLATED 70S TOWARDS THE NORTHERN SAC VALLEY AND FAVORED DOWNSLOPING 
 LOCATIONS. SHOULD SEE HIGHS IN THE 50S OVER THE HIGHER ELEVATIONS. 
 NOT EXPECTING THE PRESSURE GRADIENT TO BE QUITE AS STRONG TODAY AS 
 YESTERDAY BUT SHOULD STILL SEE A LIGHT NORTHERLY BREEZE DURING THE 
 DAY. SURFACE HIGH PRESSURE REMAINS OVER THE GREAT BASIN BUT THE 
 STRONG KATABATIC WINDS WE HAVE SEEN THE LAST FEW NIGHTS SHOULD 
 BECOME MORE ISOLATED TONIGHT. THE CURRENT FORECAST LOOKS GOOD...NOT 
 EXPECTING ANY FORECAST UPDATES AT THIS TIME. THE FOCUS IN THE SHORT 
 TERM REMAINS TO BE THE THANKSGIVING STORM SYSTEM...WILL HOPEFULLY 
 SEE SOME BETTER MODEL AGREEMENT WITH THE 12Z MODEL RUNS. DANG
 
 .PREVIOUS DISCUSSION...
 NEXT SYSTEM APPROACHES THANKSGIVING BRINGING A CHANCE OF 
 PRECIPITATION TO THE NORTHERN MOUNTAINS AND NORTHERN SACRAMENTO 
 VALLEY BY LATE IN THE DAY. A BETTER CHANCE OF PRECIPITATION IS 
 EXPECTED TO SPREAD ABOUT AS FAR SOUTH AS I-80 THURSDAY NIGHT AND 
 EARLY FRIDAY. SIMILAR TO THE LAST COUPLE OF SYSTEMS...QPF EXPECTED 
 TO BE QUITE LIGHT AS SYSTEM WEAKENS AS IT SPLITS MOVING INTO THE 
 WEST COAST RIDGE. DRY WEATHER WITH BREEZY NORTH WINDS DEVELOPS IN 
 THE SYSTEM/S WAKE ON FRIDAY.
 
 .EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)...
 MODELS BUILD A HIGH AMPLITUDE RIDGE ALONG THE WEST COAST THROUGH THE 
 PERIOD. THE 06Z RUN OF THE GFS HAS A 110KT JET ON THE BACKSIDE OF A 
 DEPARTING SHORT WAVE AIMING INTO THE NORTHERN GREAT BASIN SATURDAY 
 MORNING...WHILE THE 00Z ECMWF WAS LESS PROGRESSIVE...KEEPING THE  
 JET DIRECTLY OVER NORTHERN CALIFORNIA. THE GEM SOLUTION WAS 
 SOMEWHERE IN-BETWEEN. MODELS ARE NOT QUITE AS STRONG WITH THE 
 SURFACE HIGH OVER IDAHO (1031MB OR SO) AS THEY WERE YESTERDAY... 
 HOWEVER THE EC STILL INDICATED 30KTS OF N WIND AT 925 MB ALONG THE 
 WEST SIDE OF THE SAC VALLEY SATURDAY MORNING. SURFACE GRADIENTS 
 INITIALLY DO NOT LOOK ALL THAT STRONG BUT WE BUMPED UP TEMPERATURES 
 INTO THE MID 60S SATURDAY AND PUT IN SOME BREEZY WORDING. EASTERLY 
 GRADIENTS REMAIN IN PLACE THROUGH SUNDAY NIGHT / MONDAY MORNING 
 BEFORE A SHORT WAVE EJECTS FROM THE GULF OF ALASKA LOW AND FLATTENS 
 THE RIDGE MONDAY AFTERNOON. FARTHER OUT IN THE EXTENDED 
 PERIOD...ABOUT HALF OF THE GFS ENSEMBLE RUNS DEVELOP A TROF ALONG 
 130W BY THE MIDDLE OF NEXT WEEK WHILE THE OTHER HALF HOLDS THE RIDGE 
 IN PLACE LONGER. SG 
 
 &&
 
 .AVIATION...
 PATCHY FOG THIS MORNING PRIMARILY IN THE NORTHERN SAN JOAQUIN AND 
 SOUTHERN SACRAMENTO VALLEYS. EXPECT AREAS OF 3-5SM BR WITH LOCALIZED 
 1/4SM FG THROUGH 19Z. OTHERWISE VFR CONDITIONS ARE EXPECTED WITH A 
 FEW HIGH CLOUDS. GUSTY EAST WINDS THROUGH E-W ORIENTED SIERRA 
 CANYONS PRIMARILY IN THE MORNING. PATCHY FOG IS EXPECTED TO 
 REDEVELOP IN SIMILAR AREAS TONIGHT. 
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...NONE. 
 
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