What is the best (including weight and volume) options for the winter sheltering in places like Sierras (Tahoe and Yosemite areas)? I like snowcave/ quinzee but it takes a while to build (especially the latter) and for safety reasons it is highly recommended that one is used by at least two people so I guess it is not an option for solo trips. 

The options I am considering are: bivy, MegaMed tent (I saw members of backcountry ski patrols use them) or plain 3-season tent. What are the prone and cons for these options?