Though the list, changed to 10 essential systems such as navigation and insulation in 2003, is designed for year-round use, your risk for running into deep trouble is higher in winter.
It's colder, wetter and darker. And, admit it, you don't always bring those 10 essentials, even in summer.
Here are 10 important items to take with you, in addition to the essentials, if you want to stay safe and comfortable in the great outdoors this winter.
Rain gear: Waterproof rain gear, including pants, really should be in your pack all year long, but especially in winter, not just to keep out moisture, but to block brutal winter winds, which can be shockingly cold in exposed conditions.
Dark sunglasses: Shades are important in summer, but they're actually more important in winter if you're traveling on snow or ice.
Bring your darkest shades in winter when sunlight reflected off snow can be blinding, even on cloudy days.
Extra light: With so few hours of daylight available this time of year, you're far more likely to end up staying outside after dark.
It can be surprisingly hard to see, especially at dusk, in the shadows of the mountains.
Everyone in your party should have a flashlight or headlamp and backup devices, too, in case a battery or bulb dies in the cold.
Illumination is part of the traditional 10 essentials, but it often gets left behind.
Snow shovel: You never know what lies beneath those serene mounds of snow.
Streams, logs and other obstacles can easily hide and make what seems like flat ground quite unstable.
One wrong step and you can posthole through the surface, even if you're wearing snowshoes.
If you find yourself waist deep in water or snow -- or, worse, buried in an avalanche, a shovel is a far better tool than your bare hands for digging out.
Outfitters make a variety of small but effective backcountry shovels that are light and compact enough to fit inside a medium-sized backpack, such as a SnowClaw. In an emergency, you could use the shovel to a make a shelter.
Sit pad: Sitting on a cold rock or icy snow can sap your warmth in minutes. Bring a lightweight foam sit pad, such as a ThermaRest Z seat or an emergency blanket so you have a soft, warm spot to sit during breaks.
Hand warmers: You've heard stories of winter travelers losing fingers and toes to frost bite.
Give yourself and edge with disposable hand warmers. If you get cold feet, opt for toe warmers that last six or more hours and stay put in your boots thanks to adhesive backing.
Extra socks: If you accidentally step into a creek and fill your boot with water, you can minimize the discomfort with a dry pair of wool socks.
Wool, even when wet, can keep you warm, unlike cotton.
Extra hat and gloves: Both these items can become easily soaked in rain and sodden snow. Bring extras in zip-close bags just in case. Avoid cotton.
Thermos: Warm up from the inside out with an insulated container of hot cocoa, coffee or even soup for comfort and extra body heat.
Carrie Strandell with the Everett Mountaineers recommends bringing a backpacking stove so you can make extra hot drinks or instant soup.
Good judgment: Sometimes the best winter essential you can have is the ability to turn back or not set out at all when conditions are not safe, said Everett Mountaineer Mike Mashock.
Knowing the mountain weather is important when venturing out, he said.
"Heavy snow accumulation and high winds are both harbingers of increased avalanche risk and make navigation very difficult," Mashock said. "The trip starts with the weather report and the plan of travel. Then comes the 10 essentials and the proper clothing."
See the Washington Trails Association at www.wta.org for trip reports and the Northwest Weather and Avalanche Center at www.nwac.us for local mountain weather and avalanche danger forecasts.
1. Navigation: Map and compass.
2. Sun protection: Sunscreen, SPF lip balm and sunglasses.
3. Insulation: Enough clothes to keep you warm if you have to stay the night.
4. Illumination: Flashlight or headlamp, plus spare batteries and bulbs or a backup device.
5. First-aid supplies.
6. Fire: Two butane lighters or waterproof matches.
7. Repair kit and tools: Knife or multitool.
8. Nutrition: Food and emergency food in case you have to stay the night or longer.
9. Hydration: Two quarts of water for a day hike and a water purifier for long trips.
10. Emergency shelter: Tent, tarp, emergency blanket or even a trash bag.
Source: Adapted from "Mountaineering: The Freedom of the Hills"
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