FXUS66 KSTO 290027
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 PM PST SAT NOV 28 2009

.DISCUSSION...
THE NLY MFR-SAC GRADIENT STILL RUNNING ABOUT 15 MBS WITH RDD-SAC 
DOWN TO AROUND 6 MBS. NLY BARRIER JET FORECAST TO WEAKEN OVERNITE 
AS SUGGESTED BY THE 925 MBS WINDS AND WRF MODEL. THE 18Z NAM 925 MBS 
WINDS SHOWED A BAND OF N TO NELY WINDS FROM THE UPPER 30S KT RANGE 
AROUND RDD TO NEAR 50 KTS IN WRN SOLANO CO...AND THESE WINDS ARE 
INDICATIVE OF THE GUSTS THAT OCCURRED AROUND THE AREA...SUU G51 
KTS...VCB G46 KTS...RBL G37 KTS...SAC G38 KTS...SMF AND MYV G35 KTS. 
THE 925 MBS WIND FORECAST SUGGESTS THE BARRIER JET WILL WEAKEN AFT 
00Z...ALTHO IT MAY PERSIST IN WRN SOLANO CO INTO THE EVENING... AND 
OVER THE COASTAL MTNS UNTIL MIDNIGHT OR SO...AND HAVE EXTENDED THE 
WAD IN THESE AREAS FOR THE AFTERNOON PACKAGE. 

FOR THE MTNS IT IS A LITTLE DIFFERENT SCENARIO AS THE NLY GRADIENT 
IS FORECAST TO SHIFT TO A MORE ELY GRADIENT TONITE AND SUN AS 
SURFACE HIGH PRESSURE OVER ORE MOVES INLAND INTO ID AND NV. STRONG 
SUBSIDENCE OF 12 UBAR/S IS FORECAST OVER THE W SLOPE OVERNITE BUT 
WINDS ALOFT ARE FORECAST TO WEAKEN FROM 33-55 KTS TODAY TO 25-30 KTS 
TONITE AND SUN. MID LEVEL 750-500 MBS CAA IS FORECAST TO BE QUITE 
STRONG...-20 DEG C/12 HR...RESULTING IN STEEP LAPSE RATES AND 
EXCELLENT MOMENTUM TRANSFER DOWN TO THE GROUND OVER THE W SLOPES OF 
SIERNEV. THE STRONG SUBSIDENCE...INCREASING ELY PRESSURE GRADIENT 
AND STRONG MID LEVEL CAA CREATES A HIGH PROBABILITY OF EXCEEDING WAD 
CRITERIA OVER THE SIERNEV. THE STRONGEST WINDS OVER THE W SLOPES 
OF THE SIERNEV ARE LIKELY TO BE IN THE MORE E TO W ORIENTED 
CANYONS...AND ALTHO SUSTAINED WINDS MAY BE MORE WIDESPREAD...WIND 
GUSTS MAY NOT BE AS STRONG AS THIS MORNING DUE TO WEAKER UPPER LEVEL 
SUPPORT. MEANWHILE...FOR THE COASTAL RANGE...THE WEAKER WINDS ALOFT 
WILL ALSO CAUSE THE BARRIER JET TO WEAKEN OVERNITE AS WELL.  

OTHERWISE DRY WX IS EXPECTED OVER INTERIOR NORCAL AS A POSITIVELY 
TILTED RIDGE BUILDS OVER THE AREA FOR THE NEXT FEW DAYS...AND 
YESTERDAY'S CLOSED LOW...NOW OVER SOCAL...DROPS SWD INTO OLD MEX. 
CYCLONIC FLOW N OF THE CLOSED LOW WILL TRANSITION TO ANTICYCLONIC 
TONITE AND SUN...AND THE BACKWASH CLOUDS BANKING UP AGAINST THE E 
SLOPES OF THE SIERNEV IN OUR SRN ZONE 69 WILL BE ERODING/ 
DISSIPATING EARLY THIS EVENING. RADAR DETECTS SOME LIGHT SNOW OR 
FLURRIES SPILLING OVER THE E SLOPES AND INTO OUR ALPINE CO AND ERN 
TUOLUMNE COUNTIES. THIS OFFSHORE FLOW PATTERN WILL PRECLUDE FOR THE 
NEXT COUPLE OF DAYS...AND RESULT IN MAINLY CLEAR SKIES...COLD MINS 
DUE TO DRY CONDITIONS AND STRONG RADIATIONAL COOLING WHERE WINDS 
DIMINISH...AND SEASONABLY MILD DAYTIME TEMPS. SOME HIGH LEVEL 
CLOUDINESS IS LIKELY BY TUE AS THE RIDGE BEGINS TO FLATTEN. ELY 
GRADIENT FORECAST TO LINGER INTO MON...BUT THEN LIGHTER WINDS ARE 
FORECAST BY TUE MORNING WHEN PATCHY FOG MAY REAPPEAR. WITH MIN TEMPS 
IN THE 30S...SOME PATCHY FROST MAY OCCUR IN THE VLY EARLY NEXT WEEK 
ESPECIALLY IN THE RURAL AREAS.     JHM             

.EXTENDED DISCUSSION (WEDNESDAY THROUGH SATURDAY)...
STILL A FAIR BIT OF MODEL DISCREPANCY IN THE EXTENDED 
PERIOD...ALTHOUGH ALL MODELS CONTINUE WITH A DRY FORECAST. THE 
GFS/CANADIAN/ECMWF ALL HINT AT A PIECE OF ENERGY DROPPING OUT OF A 
GULF OF ALASKA TROUGH EARLY NEXT WEEK. THE GFS AND GEM HAVE 
MAINTAINED THIS PIECE OF ENERGY DROPPING SOUTHWARD AND MOVING INLAND 
TOWARDS BAJA CALIFORNIA WHILE THE ECMWF IS FASTER AND BRINGS THE 
SHORTWAVE INLAND TOWARDS THE PACIFIC NORTHWEST. THE GFS AND GEM HAVE 
SHOWN FAR SUPERIOR CONSISTENCY AS OF LATE AND PREFER THEIR 
SOLUTIONS. THESE TWO MODELS ARE HINTING AT A LONGWAVE TROUGH 
DROPPING SOUTHWARD INTO THE GREAT BASIN TOWARDS NEXT WEEKEND. WHILE 
THIS IS A DRY SOLUTION...IT COULD BRING ABOUT ANOTHER ROUND OF GUSTY 
NORTHERLY WINDS. DANG

&&

.AVIATION...
VFR CONDITIONS OVER THE SACRAMENTO AND NORTHERN SAN JOAQUIN VALLEYS 
THE NEXT 24 HOURS. NORTH WINDS 15-30KT WITH LOCAL GUSTS UP TO 45KT 
IN THE VALLEY WILL BEGIN TO SUBSIDE BY 02Z. MOUNTAINS GUSTS 40-60 KT 
POSSIBLE OVER HIGHER TERRAIN AND THROUGH CANYONS TONIGHT INTO SUNDAY 
MORNING.

&& 

.STO WATCHES/WARNINGS/ADVISORIES...
...WIND ADVISORY UNTIL 5 PM PST THIS EVENING FOR SACRAMENTO AND 
NORTHERN SAN JOAQUIN VALLEYS AND COASTAL RANGE INCLUDING 
SOUTHWESTERN SHASTA AND LAKE COUNTIES. 

...WIND ADVISORY UNTIL 6 PM PST THIS EVENING FOR THE CARQUINEZ 
STRAIT AND DELTA. 
 
...WIND ADVISORY UNTIL 10 AM PST SUNDAY FOR WEST SLOPE NORTHERN 
   SIERRA NEVADA-WESTERN PLUMAS COUNTY/LASSEN PARK-NORTHEAST 
   FOOTHILLS/SACRAMENTO VALLEY.

&&

$$