Locally, it looks like snow levels have stayed high thus far in the San Gabriel Mountains. Consequently Mountain High says they're closed and the Mt. Baldy Website is down. That makes it hard to predict what's going on at higher elevations, but even if heavy snow is falling above 9500', heavy rain has likely destroyed much of the existing snow at lower elevations.
The same can not be said of the Sierra. This looks like a storm for the books, with ESAC reporting several feet of dense snow has fallen throughout the Sierra in the last 18 hours—and another 2-3 on the way.
These giant snowfall totals in such a short time, coupled with extreme winds, make large, dangerous avalanches a virtual certainty in the backcountry. As ESAC forecaster Sue Burak says, "It really is foolish to think about skiing anywhere except Mammoth Mountain."
Baldy Bowl Avalanche & Level I SoCal Class
Avy Education: Motivation
SoCal Avalanche Classes
Avalanche Education: Reluctance