BTNF Backcountry Avalanche Bulletin
General Avalanche Hazard is MODERATE - Caution Advised
January 5, 2007
Since snow started falling on Wednesday afternoon, approximately 10" has fallen in the upper elevations of Western Wyoming. The snowpack now consists of two primary concerns. The most evident is new snow soft slabs that lie upon sliding surfaces varying from hard crusts to surface hoar. Pockets of such slab were sensitive to skier triggers today in very steep wind loaded terrain but were small in size. The other concern lies in a weak faceted layer at or near the base of the snowpack. This layer is harder to predict as slopes may be skied or ridden many times before the failure occurs. The new snow has added additional stresses to this layer, making triggering slightly more likely. This weak layer is thicker and therefore a bigger concern in the Togwotee and Grey's areas than in the Tetons, however activity has occurred in all three areas on this layer in the past week.
FORECAST FOR Friday January 05, 2007
The General Avalanche Hazard is expected to be MODERATE on Friday. Backcountry skiers and riders will have the potential to trigger soft slabs to eighteen inches in depth that lie upon hard snow surfaces and surface hoar in steep avalanche terrain. The potential also will exist to trigger deeper slabs that lie upon a well developed and preserved weak faceted layer especially in the Greys and Togwotee area where the weak layer is more developed, and is more significantly stressed by the new snow load.
Southwest Trails/Grey's River Area
The General Avalanche Hazard is MODERATE today, however DANGEROUS CONDITIONS EXIST. New soft surface slabs up to 18 inches deep formed by southwest to northwest winds lie on good sliding surfaces and weak layers and will be easily triggered by humans on steep slopes. The weight of this new snow increases the potential for backcountry users to trigger dangerous deep slabs to the ground. Yesterday afternoon a large slab avalanche 4 to5 feet deep was triggered on a north-northwest facing slope on Grayback Ridge at an elevation of 7,400 feet. Similar events are likely today. CAUTION IS ADVISED.
Sensitive soft surface slabs 6 to 18 inches deep formed by southwest to northwest winds lie upon slick crusts and buried surface hoar. These slabs were easily triggered by skiers yesterday, some on approach, and a large natural avalanche was observed on Mt. Hunt.
In the Southern Teton Range, seven skiers were caught in three separate incidents. One was buried to his waist in a small slide on Mt. Taylor. Four were caught with one completely buried and recovered alive by companions south of the Jackson Hole Mountain Resort. Another three were caught on a northerly aspect in Granite Canyon. Similar events are likely today. The load of the recent snow also presents the potential for deeper dangerous hard slabs to be human triggered on a buried weak layer of faceted snow.
Continental Divide Trails/Togwotee Pass
The General Avalanche Hazard is MODERATE today, however DANGEROUS CONDITIONS EXIST. New soft surface slabs up to 18 inches deep formed by southwest to northwest winds lie on good sliding surfaces and weak layers and will be easily triggered by humans on steep slopes.
Bridger-Teton National Forest Avalanche Center www.jhavalanche.org
Wyoming SNOTELs Snow Depth Measurements