Stay or go? That depends on what gear you have and what the consequences are. If the rest of my family are safe I would stay put. If not, its time to move. Bear in mind that I am an experianced, properly equipped, mountain survival trained individual and not an office wallah. Move from shelter to shelter and use the lee side of buildings as windbreaks. Move slowly. Drink plenty of water (use thermos flask so that it does not freeze.) Be aware that buildings can tunnel wind and snow. Keep carefull track of where you are. Expect it to take 8-10 hours or so to cover 21 miles. More if you have to move into the wind.

Don't try this unless you know EXACTLY WHAT YOU ARE DOING! Otherwise take Martin''s advice.