Forecasted highs for San Jose from Weather Underground http://www.wunderground.com/US/CA/San_Jose.html
indicating cooler and likely more unstable and soarable air for Saturday.
NWS discussion http://www.wrh.noaa.gov/forecasts/displ ... tr&pil=afd
A TROF WILL MOVE INTO THE PACIFIC NW AND NORTHERN CALIFORNIA ON SAT..
'TROF' is NWS for Trough: An elongated area of relatively low atmospheric pressure. Often colder and more unstable than the air in front of it. A 'Front', as in 'cold front' or 'warm front' is the boundary between two air masses, named for the advancing air mass.
Saturday looks like the day, but it is still a couple days away, things could change.