GNFAC Avalanche Advisory for Sun Apr 6, 2014

Not the Current Forecast

Good Morning. This is Doug Chabot with the 134th and last daily avalanche advisory of the season issued on Sunday, April 6 at 7:30 a.m. Today’s advisory is dedicated to everyone who supported our operation by reading these advisories; taking an avalanche class; donating money, time or gear; or sending in a backcountry observation. Our success is directly related to the backing of the community and Forest Service. Thank you for a great 24 seasons. This advisory does not apply to operating ski areas.

Mountain Weather

A trace to two inches of new snow fell in the last 24 hours. Under cloudy skies temperatures are in the low twenties as winds blow 20-30 mph from the southwest. A moist northwest flow will keep skies cloudy today and bring snow showers. I expect 1-3 inches by tonight with a bit more in the Bridger Range. Today winds will increase slightly and temperatures will reach the high 20s. Behind this storm a high pressure ridge will bring a week of sunny skies and warm temperatures (60F!).

Snowpack and Avalanche Discussion

Bridger Range   Gallatin Range   Madison Range   Cooke City   Lionhead area near West Yellowstone  

Yesterday the Bridger Range got a trace and Cooke City got closer to two inches of new snow with other areas receiving about an inch. A skier south of Cooke City triggered a small soft slab avalanche in the new snow, but otherwise the backcountry has remained quiet. A layer of surface hoar formed on north facing slopes in Beehive Basin on Wednesday (photo) and is now buried six inches under the surface. This layer may have formed in other ranges too. It’s unlikely to survive this week’s warm temperatures, but it’s worth looking for since it would be the weakest layer in the snowpack.

Strong winds today will form soft wind slabs near the ridgelines. These will crack and possibly avalanche as you pass by. Cornices are large and Big Sky Ski Patrol reported one cracking 10 feet back. These can pose dangers to passing skiers and trigger avalanches below. 

To recap, new snow avalanches, wind drifts, cornices and shallowly buried surface hoar are on our radar. While no single threat overwhelms the backcountry, any one of these could ruin your day. For this reason the avalanche danger is rated MODERATE on all slopes throughout our advisory area.

Cornices: Cornices are growing at a fast rate and are getting quite enormous this season. They can break with a passing skier and deserve a wide berth. A falling cornice can also be a very good trigger for deep slab avalanches. 

If conditions warrant we will issue intermittent avalanche information. If you have any snowpack or avalanche observations drop us a line at mtavalanche@gmail.com or call us at 587-6984.

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