I study the Sierra snowpack levels pretty steadily every spring as I plan my backcountry ski trips. The one thing you can count on is that at this point in the season we don't know diddly about what the snowpack will be come June. The odds of a low total snowpack are higher this year given what is up there now, but if we get a big fat Feb and Mar we could get right back up to average. The official average is based on the April 1st measurement, and at that point you have a fair idea of how things will pan out, but even then you cant tell for sure - April and May could be cold and snowy. Personally, if I had the schedule flexibility, I'd wait until May 1st. By then it should be pretty clear what's going on. Here's a link to the page with all the snow survey stuff, including real-time sensors which are the most fun:
It's a litle confusing at first. For the real-time stuff, look for " Latest Real-time Snow Water Content Data". they have it arranged by river basin, and there are links to rather sketchy maps of where the sensors and snow courses are located.