So, NOAA predicts up to 14 inches heading your way this week. I've been on Cassaval a number of times and I can almost guarantee you that once you reach the top of Giddy Giddy and you become exposed to some of those raunchy winds that Shasta is notorious for, you'd be hard-pressed to get your tent erected, much less make a push in cruel conditions for the summit. The avy advisory looks okay at "moderate" but watch out during your initial push to gain the ridge. That initial hump will be wind-loaded with all Horse camp as a terrain trap. Ive seen it slab off before, especially on the SE side.
If you go for it, I wish you good luck. Be careful out there though man.