AREA FORECAST DISCUSSION

 
 FXUS66 KSTO 241149
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 345 AM PST TUE NOV 24 2009
 
 .DISCUSSION...
 DRY AND MILD WEATHER WILL CONTINUE TODAY AND WEDNESDAY AS A BROAD 
 RIDGE OF HIGH PRESSURE ALOFT COVERS THE WESTERN US. A VERY WEAK 
 SHORT WAVE MOVING OVER THE RIDGE WILL BRING A FEW MID AND HIGH LEVEL 
 CLOUDS TODAY...BUT OTHERWISE CLEAR SKIES EXPECTED UNTIL 
 THANKSGIVING. THIS WILL CONTINUE TO RESULT IN GOOD RADIATIONAL 
 COOLING AT NIGHT LEADING TO PATCHES OF LATE NIGHT AND MORNING FOG IN 
 THE CENTRAL VALLEY AND MOUNTAIN VALLEYS. LOCALLY GUSTY 
 NORTHEAST/EAST WINDS WEST FACING CANYONS AND HIGHER ELEVATIONS 
 NORTHERN SIERRA EARLY THIS MORNING AND AGAIN TONIGHT AND EARLY 
 WEDNESDAY MORNING AS STRONG SURFACE HIGH PRESSURE REMAINS CENTERED 
 OVER THE GREAT BASIN.
 
 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 
 
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 .AVIATION...
 STRONG SURFACE HIGH PRESSURE HAS SHIFTED FARTHER EAST INTO NEVADA AS 
 STRONG RADIATIONAL COOLING HAS DEVELOPED IN THE CENTRAL VALLEYS. 
 AREAS 3-5SM BR WITH ISOLD IFR 1SM BKN005 TIL 17Z POSSIBLE AT 
 KSMF...KSAC AND KSCK. VFR LIKELY FOR KRDD AND KRBL AS HIGH CLOUDS 
 ARE LIMITING COOLING. IN GENERAL TODAY VFR SKC-SCT250 EXPECTED. 
 GUSTY EAST WINDS THROUGH E-W ORIENTED CANYONS THIS MORNING ALONG THE 
 W SLOPES OF THE SIERNEV AND OVER RIDGES. LOCAL LIFR 1/4SM FG IN HIGH 
 MOUNTAIN VALLEYS 13Z-17Z. SG
 
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 .STO WATCHES/WARNINGS/ADVISORIES...NONE. 
 
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