552   
FXUS66 KSTO 062356 AAA  
AFDSTO  
  
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SACRAMENTO CA  
330 PM PST TUE JAN 6 2009  
   
DISCUSSION  
  
TEMPERATURES WARMED INTO THE UPPER 50S IN MANY VALLEYS AFTER THE LOW   
CLOUDS AND FOG CLEARED OUT. THE EXCEPTION HAS BEEN THE STOCKTON AND   
MODESTO AREAS...WHERE STRATUS CLOUDS ARE JUST NOW BEGINNING TO THIN.   
HIGH PRESSURE ALOFT AND AT THE SURFACE WILL ALLOW TEMPERATURES TO   
COOL RAPIDLY TO THE DEWPOINT OVERNIGHT. EXPECT WIDESPREAD FOG TO   
DEVELOP AND BE DENSE IN SOME AREAS. PRESSURE RISES OVER THE GREAT   
BASIN SHOULD KEEP LOCALLY BREEZY NORTHEAST WINDS IN THE EASTERN   
FOOTHILLS AND MOTHERLODE...AND KEEP FOG FROM FORMING THERE. FOG IS   
ALSO LIKELY IN MOUNTAIN VALLEYS OVERNIGHT. THE TEMPERATURE AT BLUE   
CANYON...NEAR 5280 FEET...WAS NEARLY THE SAME AS IT WAS IN   
SACRAMENTO TODAY.    
  
BELIEVE THE FOG WILL LIFT TO A STRATUS LAYER TOMORROW. IT MAY HANG   
AROUND FOR MOST OF THE DAY. WE TRENDED HIGH TEMPERATURES BELOW MOS   
GUIDANCE AND INDICATED ONLY PARTIAL CLEARING IN THE AFTERNOON   
TOMORROW. THE SOUTHWEST FLOW ALOFT INCREASES WEDNESDAY NIGHT AHEAD   
OF A FAIRLY POTENT SHORT WAVE THAT IS EXPECTED TO WEAKEN AS IT   
APPROACHES CALIFORNIA THURSDAY. THIS SYSTEM HAS A DECENT MOISTURE   
TAP ON THE SATELLITE AND TIME/HEIGHT SECTIONS INDICATE FAIRLY STRONG   
VERTICAL MOTION PEAKING AROUND 18Z THURSDAY. MODEST 90KT JET AND   
700MB WINDS UP TO 50 KTS WILL PROVIDE A BRIEF PERIOD OF MODERATE TO   
HEAVY VALLEY RAIN AND MOUNTAIN SNOW SHOWERS THURSDAY. THE GFS   
INITIALIZED WRF BRINGS THE COLD FRONT THROUGH SACRAMENTO AROUND 21Z   
THURSDAY. WITH PERHAPS 0.5 INCHES OF QPF WE COULD HAVE A 6 TO 12   
INCH SNOWFALL OVER THE HIGHER MOUNTAIN PASSES...MAINLY FROM I-80   
NORTH. THE 18Z GFS CAME IN A BIT MORE PROGRESSIVE WITH THE   
LOW...SIMILAR TO THE ECMWF. THE EASTERN PACIFIC RIDGE BUILDS   
STRONGLY TOWARD THE COAST AS THE PATTERN AMPLIFIES FRIDAY. SOME   
MODELS...ESPECIALLY THE ECMWF IS SUGGESTING STRONG NORTH WINDS AND   
WELL ABOVE NORMAL TEMPERATURES WILL DEVELOP FRIDAY. INDICATED   
MILDER AND BREEZY WORDING IN THE FRIDAY FORECAST FOR NOW. SG  
   
EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)  
  
RELATIVELY LITTLE WEATHER EXPECTED IN THE EXTENDED PERIODS AS THE   
EASTERN PACIFIC RIDGE BUILDS TOWARDS CALIFORNIA. THE EXPECTATION IS   
FOR MODERATE OFFSHORE FLOW TO DEVELOP AS SURFACE HIGH PRESSURE   
BUILDS INTO THE GREAT BASIN SATURDAY. THIS SHOULD BRING WARMER THAN   
NORMAL TEMPERATURES AND CONDITIONS DRY ENOUGH TO PUSH THE THREAT OF   
FOG INTO THE SOUTHERN HALF OF THE CENTRAL VALLEY. THE HANDLING OF   
HOW FAR THE RIDGE PUSHES EASTWARD BECOMES A BIT MORE UNCERTAIN BY   
THE EARLY PART OF NEXT WEEK. IF THE UPPER RIDGE MAKES IT OVER   
CALIFORNIA...FOG IS LIKELY TO REDEVELOP UNDER WIDESCALE SUBSIDENCE   
AND LIGHT WINDS. IF THE UPPER RIDGE STAYS OFF THE COAST...OFFSHORE   
FLOW WOULD CONTINUE AND MITIGATE FOG DEVELOPMENT. AT THIS POINT HELD   
OFF ON ANY MENTION OF FOG...BUT WILL NEED TO SEE HOW THIS   
MATERIALIZES OVER THE NEXT FEW MODEL RUNS. DANG  
  
  
   
AVIATION  
  
MOST OF THE MORNING STRATUS AND FOG HAS BURNED OFF NORTH OF HWY   
50...WITH MVFR STRATUS REMAINING IN THE NORTHERN SAN JOAQUIN VALLEY.   
EXPECT AREAS OF IFR TO LIFR FOG TO REDEVELOP LATE THIS EVENING   
THROUGH MOST OF THE CENTRAL VALLEY WITH LIGHT WINDS...AND LIFT TO A   
VFR TO IFR STRATUS DECK AFTER 20Z WEDNESDAY.  
  
  
   
STO WATCHES/WARNINGS/ADVISORIES.  
NONE.   
  
  
  
  
 
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