Ski resorts in California are regularly blessed by sunshine, clear blue skies and joyous powder dumps. Snowboarding in a T-shirt is possible on certain days, but be careful of face-planting. The variety at Tahoe is great and there's something for all skill levels. You can improve your technique at a cheap resort like Donner and work upto the bigger expensive resorts of Squaw and Heavenly.
The only downside to Tahoe is that some of the resorts are fairly low in elevation for the mild California weather conditions. This can lead to days where you're boarding in the rain (strangely?) or screeching to a halt as your board hits the slushy snow. You can't have everything I suppose.