By Chuck Nottingham
Montana provides all three corners of the "avalanche triangle," elements necessary for potential catastrophes estimated to take place a million times a year in the right (or wrong) places on our planet: Steep mountainsides, dense winter snow-packs, and quickly-changing weather.
Montana avalanches slide into (sorry) the three distinct categories.
Dry avalanches let go when tons of powdery snow accumulate on slopes with few or no rocks or trees to hold it in place. Gravity overcomes resistance, and it slides, producing little friction so the mass can roar down at 100-plus miles per hour generating hurricane-like winds. Dry avalanches are those people and animals miraculously survive by "swimming" along at its surface but most die of trauma and suffocation.
Wet avalanches also consist of loose snow, but partially melted and more weighty. Also often prevented from becoming avalanches by rock formations and tree-stands, wet avalanches move much slower, but often make little sound to warn people below except snapping trees as they begin to move. Most people and animals surviving wet avalanches see them coming and move out of their paths.
Slab avalanches are as destructive as dry avalanches. Large sections of solid ice and snow break loose from dense snow-fields and slide as slabs, fragmenting and tumbling, grinding all they roll across like juggernauts. Little in their paths survive.
Like flash floods and lightning strikes discussed in later issues of this outdoor section, nature and terrain give us warnings of avalanches when we pay attention. Unlike flash-floods and lightning, avalanches are similar to hunting "accidents," in that they are often caused by the victim or someone in the group.
Although "acts of God" such as winds and tremors touch off avalanches, it's no coincidence many that injure and kill are triggered by people around them. Skiers, snowshoers, and snowmobilers start hundreds of avalanches every year.
Learn the signs. If you're in a sloping trench swept clean of other vegetation than snapped-off tree-trunks, you're in an avalanche chute. If the snowfield you're on or above you is large, crowned, and steep especially with no rocks or trees protruding from it you're in the right (or wrong) place for the ride of your life, short as that may be. Conditions are worsened after heavy snowfalls or after a day or two of warm weather.
Do not cross the snowfield. Get off, and do not traverse below it. If that means turning back, then turn back.
Always check for avalanche conditions at the nearest U.S. Forest Service station before entering avalanche country.
Glacier Country Avalanche Center features snow-pack analysis, avalanche outlook, instability advisory, and danger classification. Missoula Regional Avalanche Advisory updates every Friday at noon. Gallatin National Forest Avalanche Center in Bozeman is also available by phone, (406) 587-6984, and e-mail.
Those who work or play in avalanche country should always carry and know how to use safety equipment. A few items are extra food and water, flashlights, probes to find people under the snow, entrenching tools to dig out or dig others out, radios or transceiver-locators.
A gruesome tip should members of your group be caught in an avalanche: Time is of the essence. Make sure victims are dead before going for help, or you can be sure they'll be dead when you return.