342  
FXUS66 KSTO 262205  
AFDSTO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SACRAMENTO CA  
305 PM PDT THU APR 26 2018  
   
SYNOPSIS
 
 
ISOLATED SHOWER/THUNDERSTORM POSSIBLE OVER THE HIGHER TERRAIN  
THIS AFTERNOON INTO EVENING. COOLING WITH AN INCREASING CHANCE AND  
AREAL COVERAGE OF SHOWERS AND AFTERNOON THUNDERSTORMS FRIDAY INTO  
THE WEEKEND. THREAT OF MOUNTAIN SHOWERS/THUNDERSTORMS LINGERS  
INTO EARLY NEXT WEEK.  
 

 
   
DISCUSSION
 
 
CU/TCU DEVELOPING OVER THE HIGHER ELEVATIONS OF THE WESTERN PLUMAS  
MOUNTAINS AND SIERRA NEVADA THIS AFTERNOON. NAM 3KM SHOWING  
ISOLATED STORMS DEVELOPING LATER THIS AFTERNOON INTO EVENING NEAR  
THE CREST. AFTERNOON TEMPERATURES ACROSS INTERIOR NORCAL RUNNING  
ABOUT 3 TO 9 DEGREES COOLER WITH GREATEST CHANGE OBSERVED IN THE  
SOUTHERN AND CENTRAL SAC VALLEY. DELTA BREEZE IS MODERATE TO  
STRONG THIS AFTERNOON AND WILL CONTINUE SIMILAR STRENGTH THIS  
EVENING.  
 
CLOSED UPPER LOW IS FORECAST TO GRADUALLY SHIFT INLAND FRIDAY INTO  
THE WEEKEND WITH LOW CENTER TRACKING ACROSS OREGON. INCREASED  
SYNOPTIC FORCING AND INSTABILITY WILL RESULT IN HIGHER PROBABILITY  
OF MOUNTAIN SHOWERS AND THUNDERSTORMS. THREAT ALSO EXTENDS INTO  
PORTIONS OF THE CENTRAL VALLEY AND FOOTHILLS WITH BEST CHANCES IN  
THE AFTERNOON AND EVENING FROM AROUND KCIC NORTHWARD. STRONGEST  
CELLS LOOK TO OCCUR OVER NORTHERN PORTIONS OF THE CWA, CLOSER TO  
LOW CENTER. ENHANCED ONSHORE FLOW AND SYNOPTIC COOLING WILL  
RESULT IN HIGH TEMPERATURES DROPPING ABOUT 5 TO 15 DEGREES FRIDAY  
INTO THE WEEKEND. COOLEST DAY LOOKS TO BE SATURDAY WITH HIGHS  
EXPECTED IN THE 60S FOR THE CENTRAL VALLEY, WITH 40S TO 50S FOR  
THE MOUNTAINS AND FOOTHILLS.  
 
PCH  
 

 
 
.EXTENDED DISCUSSION (MONDAY THROUGH THURSDAY)  
LARGE SCALE UPPER LEVEL DISTURBANCE WILL BEGIN SHIFTING EAST  
MONDAY, BUT ANOTHER FAST MOVING SHORTWAVE TROUGH WILL DIVE  
SOUTHWARD ALONG THE COAST TO CONTINUE TO BRING CHANCES FOR  
MOUNTAIN SHOWERS AND ISOLATED THUNDERSTORMS AND COOLER WEATHER  
ACROSS INTERIOR NORTHERN CALIFORNIA. AFTERNOON HIGH TEMPERATURES  
MONDAY WILL BE SLIGHTLY BELOW NORMAL, BUT WILL REBOUND TO NEAR TO  
SLIGHTLY ABOVE NORMAL BY THE MIDDLE OF NEXT WEEK.  
 

 
   
AVIATION
 
 
VFR CONDITIONS FOR THE TERMINALS OVER THE NEXT 24 HOURS WITH  
INCREASING HIGH LEVEL CLOUDS. LOCAL IFR CONDITIONS POSSIBLE NEAR  
THE BAY / DELTA REGION DURING THE MORNING HOURS, AND ISOLATED  
THUNDERSTORMS ARE POSSIBLE OVER THE HIGH SIERRA THIS AFTERNOON.  
 

 
   
STO WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
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