Glenn is partly right, these tents are not extreme winter tents, but that is not what they are designed for. However the Cirque, the Arete and similar models can be closed up, just like mine.
From the REI website-
•Cirque can be used in a variety of seasons and climates: inner tent is fully closeable with zippered panels that cover the mesh doors and vents
There are ways to make a 3 or 3/4 season tent more likely to survive in extreme weather-one way if the snow is deep enough is to dig out a hole for it so it sits below the snow level. That's where a shovel comes in. Even on Denali, in winter tents, climbers will dig in the tents and make wind walls; then again, Denali can get winds up to 100mph from what I have read. I mentioned a shovel in another thread asking a similar question -I carry a Voile Mini in winter, not that heavy and very handy. I always take mine if there is snow on the ground, even on a day hike.
If you want to learn more about winter camping, get yourself a copy of Allen & Mike's Really Cool Backcountry Ski Book, about $10 at Amazon. Don't be put off by the title, about half the book is about winter camping.
Edited by TomD (10/08/12 12:53 AM)
Don't get me started, you know how I get.