It's gonna be nasty ... but see the NWS note that main stem rivers are expected to be OK. That's probably because we've had so little rain that they're very low and any reservoirs on them are nearly empty. And they're predicting 15-20 inches in the heavy spots - still a little on the low side for a big event. And finally the heaviest blast seems to be heading for central/south state not north, so the N.State rivers (Eel etc.) may not be as hard hit as the smaller ones around the Bay and in the Sierra. Napa will almost certainly flood.

The better part of the picture is 10' of snow at the higher Sierra elevations by the end of the week (with 60-100 mph winds over the crest i.e. "blowing" snow). Good for the water supply and the skiers, but will it bring out the UP snow gear or will they just stop running and settle in for the duration?

BTW, if you type "Island Mountain, CA" into the location box it comes up with a local forecast for the spot.