Ten Day precipitation and temperature map:

http://wxmaps.org/pix/prec1.html

Technical (!) forecast discussions by state meteorologists:

http://www.weather.gov/view/prodsByState.php?state=ca&prodtype=discussion

Seven day forecast for South Lake Tahoe and above 7000 feet:

http://www.wrh.noaa.gov/forecast/MapClick.php?minlon=-123&maxlon=-115&minlat=37.39&maxlat=42.03&mapwidth=354&site=rev&map.x=137&map.y=182

California Highway conditions:

http://www.dot.ca.gov/hq/roadinfo/