006   
FXUS66 KSTO 122018  
AFDSTO  
  
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SACRAMENTO CA  
118 PM PDT TUE AUG 12 2025  
   
DISCUSSION  
  
   
SYNOPSIS  
  
AREAS OF MODERATE HEATRISK WITH TRIPLE DIGIT HIGHS IN THE NORTHERN  
SAC. VALLEY THIS AFTERNOON AHEAD OF A COOLING TREND FOR THE  
REMAINDER OF THE WEEK. NON-ZERO CHANCE OF ISOLATED MOUNTAIN   
SHOWERS AND THUNDERSTORMS THIS AFTERNOON, SOUTH OF INTERSTATE 80.  
  
  
   
KEY MESSAGES  
  
*TODAY:  
 - AREAS OF MODERATE HEATRISK TODAY OVER THE NORTHERN/CENTRAL  
   SACRAMENTO VALLEY AND ADJACENT FOOTHILLS;COOLING TREND  
   ELSEWHERE  
 - PROBABILITY OF HIGH TEMPERATURES > 100F:   
    -NORTHERN SACRAMENTO VALLEY: 70-95%  
 - AFTERNOON HIGHS IN THE MID 90S TO MID 100S WITH DRY CONDITIONS  
   OVER THE NORTHERN SAC VALLEY (MIN RHS - 15-25%)  
 - NON-ZERO CHANCE OF ISOLATED MOUNTAIN THUNDERSTORMS MAINLY SOUTH  
   OF INTERSTATE 80 IF ANYTHING DOES DEVELOP  
  
*WEDNESDAY-FRIDAY:  
 - THE EAST PACIFIC RIDGE AXIS ALOFT WEAKENS AS AN UPPER TROUGH   
   FROM WESTERN CANADA DROPS DOWN BRINGING INCREASED ONSHORE FLOW,  
   COOLER TEMPERATURES, AND HIGHER RELATIVE HUMIDITY  
 - THE INCREASED DELTA BREEZE WILL GIVE NOTICEABLE RELIEF FOR THE  
   DELTA AND SOUTHERN SACRAMENTO VALLEY BY WEDNESDAY MORNING  
 - AFTERNOON HIGHS COOLING TO UPPER 80S TO UPPER 90S THIS WEEK  
    
*WEEKEND:  
 - NEAR TO BELOW AVERAGE TEMPERATURES THEN CONTINUE LATER THIS  
   WEEK AND INTO THE WEEKEND WITH RISING RELATIVE HUMIDITY  
 - PERIODICALLY BREEZY ONSHORE FLOW IS FORECAST AT TIMES,  
   STRONGEST IN THE DELTA VICINITY AND OVER THE SIERRA CREST  
 - LOW CONFIDENCE IN ISOLATED THUNDERSTORM POTENTIAL ALONG THE  
   HIGHER ELEVATIONS IN THE MOUNTAINS THIS WEEKEND (10-15% CHANCE),  
   DRY WEATHER ELSEWHERE  
    
CHANGES FROM PREVIOUS FORECAST  
  
- NO SIGNIFICANT CHANGES TO THE FORECAST AT THIS TIME.   
   
  
   
AVIATION  
  
VFR CONDITIONS CONTINUE THE NEXT 24 HOURS OVER INTERIOR NORCAL.  
SURFACE WINDS GENERALLY BELOW 12 KNOTS, WITH A BRIEF PERIOD FROM  
AROUND 22Z TODAY THROUGH 16Z WEDNESDAY WITH WEST-SOUTHWEST   
SURFACE WINDS GUSTING UP TO 30 KNOTS IN THE DELTA AND SOUTHERN   
SACRAMENTO VALLEY.   
  
  
   
STO WATCHES/WARNINGS/ADVISORIES  
  
NONE.  
  
  
  
 
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