Tuesday, February 23, 2016

Winter Backcountry Travel 101: Improvised Snow Shelters


What to do with spare time at 14,000ft camp on Denali?  
Build a 16-person igloo! (Photo Credit: Dylan Cembalski)

So you're getting ready to spend an overnight in the mountains in winter. Even seasoned summer backcountry campers will find significantly more difficult challenges in winter camping; shorter days, a harsher climate, harder-earned water sources, and a deep snowpack as the only available medium on which to camp. With a little know-how and practice however, the latter can become your friend.

Snow is an excellent insulator. Snow inherently has so much air inside of it that it traps up to 95% of heat transfer. Also, because of this very principle, the snow closer to the ground will be warmer than the snow at the surface. This is why snow caves can be so comfortable. I have dug many snow caves, and spent many nights 10 ft deep in a Pacific Northwest snowpack, and while snow caves are super warm, they are time consuming to create. With two people, the fastest I have been able to dig out a proper cave is about 2 hrs. These days, I pretty much always just dig what is known as an improvised snow shelter. The improvised snow shelter doesn't have quite the insulating ability of a proper cave, but can be dug in 30 minutes and, if sealed proper, can retain a lot of heat without the moisture associated with the dripping roof of a slept-in snow cave.

Improvised Snow Shelter

The gear needed for an improvised snow shelter is pretty minimal. The shelter can take many forms to match the terrain and weather constrictions. If you have a lee-side incline with safe snow conditions, this will provide the best coverage with the least amount of digging. All you will really need is an ultra-light tarp equipped with guy-lines and stakes, and a shovel. I find that adding an extra-large emergency blanket to my sleeping setup really makes a difference in staying warm and dry. The idea is simple- measure out the area you have to work with by spreading out the tarp over the spot you've chosen. Mark the boundaries, then dig out the area, going as deep into the snow as you can- at least 6 feet. Flatten out the bottom of your pit. I like to dig out an area in the pit heading into the hillside that will be used for my kitchen. Make sure to poke some good-sized holes through the snow above this area to allow for adequate ventilation.

 After the pit is dug, carve out an entryway in one of the downhill corners. At a minimum, I try to make my entryway two feet deeper than the floor of my pit. This will create a 'cold-sink' (a place for cold air to escape thus allowing more hot air into the enclosure), provide protection from the elements, and a comfortable seat to put boots on. I then make sure to put an angle or curve into the walkway to further block wind from entering the shelter. When this is all complete, I tension out the tarp over the pit. Once it is tight, seal off the pit by putting snow on top of the tarp's edges and corners. Voila! Improvised shelter, complete!

                  Laying the groundwork for an improvised snow       The final product. (A.Stephen)
                      shelter (A. Stephen)


Staying Dry and Warm

The hardest part about camping and sleeping directly on snow is staying dry and warm.  The first step in this process begins when you leave the car.  Throughout the day, including when you begin to dig out your shelter, be cognizant of keeping crucial layers dry.  Any items that are impossible to keep dry such as gloves and socks, you should double up on.  While down jackets and sleeping bags are warm and packable, consider bringing either a jacket or sleeping bag that is synthetically insulated, since these pieces will retain their warmth even if they get wet.  If anything you are wearing starts to get full-on soaked, switch it out or find a way to dry it out immediately.  Drying out clothing in your sleeping bag at night is possible, but keep in mind that anything that is completely soaked is highly unlikely to be dry by morning, and the more wet things you pack around you, the more potential there is to spend the night shivering instead of sleeping.

An emergency blanket will come in handy to line the floor of your shelter so as to provide a bit of reflective heat, as well as a barrier from the snow in case your bag slides off your pad in the night, or if you need to make a quick exit.  If you are religious about staying dry, chances are you will be able to escape being cold, but going to sleep with a nalgene filled with boiling water can go a long ways toward making sure of this.

As with most mountain travel principles, experience is an equal to knowledge.  So go out and practice before you put yourself in a situation where you are fully dependent on your shelter.  I recommend packing extra warm layers your first few times using an improvised snow shelter so you can dial in your sleeping system without worrying about the consequences of any missteps.  As always, the American Alpine Institute is available to teach these skills in a more comprehensive, hands-on manner, helping you gain the knowledge and experience to become a smart and self-reliant backcountry traveler, climber, and skier. 

-Andy Stephen, Instructor and Guide

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