Backcountry Avy Hazard High

Written by wade on February 1, 2010 – 11:03 am -

Here is the report from the Bridger-Teton National Forrest Backcountry Avalanche Hazard & Weather Forecast. Go to www.jhavalanche.org to read the entire report.

January 30, 2010

Dangerous conditions exist. Multiple incidents occurred in all of our forecast areas yesterday afternoon. Snowmobilers in terrain above Ski Lake reported that an extremely large full depth hard slab avalanche released on a northeast aspect. The crown was reported to be up to 12 feet deep and 2,000 feet long. It took out mature trees. In the Snake River Range a skier was caught and deployed an airbag as he was being swept downhill. He was partially buried but not injured. A different slope failed after being crossed by the fifth skier. On Togwotee Pass two snowmobilers were caught and injured by a hard slab avalanche. Three people have been killed or seriously injured by avalanches in the past three days in Utah and Idaho. On steep slopes, dangerous full depth hard slabs could be triggered by a single person or more likely by a snowmobile. Conservative decisions regarding terrain selection are essential today.

January 31, 2010

Multiple incidents occurred in all of our forecast areas Friday afternoon. Yesterday, a snowmobiler was killed by a 3 to 4 foot deep hard slab avalanche in the Big Holes. Our deepest condolences go out to the victim’s family and friends. New snow, falling upon crusts and surface hoar, will slowly increase the possibility for backcountry travelers to trigger new, shallow soft slabs and loose snow sloughs. Far more dangerous are the deep slab instabilities that plague the region. These hard slabs lie upon a base of weak, faceted snow, and could fail to the ground. A single person, and more likely a snowmobile, could trigger these avalanches even after a slope has been crossed multiple times. Conservative decision making regarding terrain selection will be essential for safe travel in the backcountry today.

Feb. 1, 2010

At upper elevations eighteen inches of new snow in the past 24 hours has been drifted by southwest winds into easily triggered or naturally releasing soft slabs to three feet in depth. The new snow rests on good sliding surfaces of sun crusts or buried surface hoar. The snow is light density but has added strain to the deep, hard slab instabilities that plague the region. These poorly supported slabs that also exist at mid elevations could fail to the ground and may be triggered by new snow surface slides, a single person, and more likely a snowmobile even after a slope has been crossed multiple times. At the mid and low elevations sloughs could build to dangerous size in steep areas and terrain traps. TRAVEL IN AVALANCHE TERRAIN AT UPPER ELEVATIONS IS NOT RECOMMENDED TODAY

 


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