029  
FXUS66 KSTO 200950  
AFDSTO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SACRAMENTO CA  
250 AM PDT WED SEP 20 2017  
   
SYNOPSIS
 
 
COOLER WEATHER CONTINUES THIS WEEK WITH A CHANCE OF SHOWERS INTO  
THURSDAY.  
 

 
   
DISCUSSION
 
 
WESTERN NORTH AMERICA TROUGH CONTINUES TO EVOLVE WITH THE INITIAL  
WAVE FROM EARLIER THIS WEEK NOW LIFTING OUT THROUGH THE NORTHERN  
GREAT PLAINS WHILE THE NEXT WAVE DROPS SOUTH OFF THE PACNW COAST.  
ACROSS INTERIOR NORCAL, SKIES ARE PARTLY TO MOSTLY CLOUDY TO THE  
NORTH OF I-80 WHILE THEY'RE CLEAR TO THE SOUTH. RADAR INDICATES  
SHOWERS HAVE SO FAR BEEN REMAINING OVER NORTHWEST CALIFORNIA.  
 
CURRENT TEMPERATURES RANGE FROM THE MID 30S TO MID 40S IN THE  
MOUNTAIN VALLEYS TO THE MID 50S TO MID 60S IN THE CENTRAL VALLEY.  
 
THE UPPER TROUGH IS FORECAST TO DEEPEN ACROSS NORCAL OVER THE NEXT  
24 HOURS PUSHING ANOTHER COLD FRONT SOUTHWARD LATER TODAY AND THIS  
EVENING. MOST PRECIPITATION IS EXPECTED OVER THE MOUNTAINS AS THE  
FRONT MOVES THROUGH, BUT SOME SPRINKLES OR LIGHT SHOWERS MAY  
BRUSH THROUGH PORTIONS OF THE VALLEY AS WELL. QPF WILL BE LIGHT,  
GENERALLY LESS THAN A THIRD OF AN INCH ACROSS THE HIGHER  
ELEVATIONS AND LESS THAN A TENTH OF AN INCH ELSEWHERE.  
 
COLDER AIR WILL MOVE INTO THE REGION TONIGHT BEHIND THE FRONT  
LOWERING SNOW LEVELS TO AROUND 5500-6500 FEET. EVEN A FEW INCHES  
OF SNOWFALL ACCUMULATION WILL BE POSSIBLE ACROSS THE HIGHER PEAKS.  
 
TEMPERATURES WILL BE WELL BELOW AVERAGE (10-20 DEGREES) ACROSS  
THE REGION THE NEXT FEW DAYS WITH HIGHS ONLY IN THE 70S ACROSS THE  
CENTRAL VALLEY THROUGH FRIDAY.  
 
DRY AND MILDER WEATHER RETURNS FOR THE WEEKEND.  
 

 
 
.EXTENDED DISCUSSION (SUNDAY THROUGH WEDNESDAY)  
HIGH PRESSURE RETURNS TO NORTHERN CALIFORNIA THIS WEEKEND WITH  
DRY CONDITIONS AND A WARMING TREND TO THE AFTERNOON TEMPERATURES.  
HIGH TEMPERATURES SATURDAY WILL REMAIN BELOW NORMAL, BUT  
TEMPERATURES SUNDAY INTO EARLY NEXT WEEK WILL RETURN TO NORMAL OR  
SLIGHTLY ABOVE NORMAL. BREEZY NORTH AND EAST VALLEY AND RIDGETOP  
WINDS CAN BE EXPECTED FOR THE WEEKEND AND INTO NEXT WEEK.  
 

 
   
AVIATION
 
 
VFR CONDITIONS FOR THE VALLEY TERMINALS FOR THE NEXT 24 HOURS  
WITH LIGHT WINDS. CHANCES FOR LIGHT MOUNTAIN RAIN SHOWERS AND  
INCREASING CLOUDS TONIGHT AND WEDNESDAY.  
 

 
   
STO WATCHES/WARNINGS/ADVISORIES
 
NONE.  
 

 
 

 
 
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