Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, February 9, at 7:30 a.m. Team Bozeman and Yamaha, in cooperation with the Friends of the Avalanche Center, sponsors today’s advisory. This advisory does not apply to operating ski areas.
Under clear skies mountain temperatures are in the single digits below zero this morning. In the Bridger Range winds shifted last night from the east to the west at 20-25 mph. West to northwest winds are blowing 15-25 around Big Sky, but are less than 10 mph around West Yellowstone and Cooke City. Mostly sunny skies will help raise temperatures into the low teens as high pressure builds this weekend. Temperatures will drop to near zero tonight with no likelihood of precipitation.
The Bridger and northern Gallatin Ranges:
The Bridger and northern Gallatin Ranges got hit with east winds yesterday, a rare occurrence. These created cornices and drifts on west facing slopes that are now getting re-blown 180 degrees. I get dizzy just writing about it. The bottom line is that winds are depositing snow in unusual places. With almost 30 inches from the weekend, there’s more than enough snow to drift. Besides windblown snow, there are small grains of facets underlying the new snow. This layer avalanched on Sunday near Frazier Lake in two separate skier triggered slides. One person was flown by helicopter to the hospital with a broken femur (accident report). Yesterday, Eric took a picture of an avalanche in Argentina Bowl to the south of the Bridger ski area. We know that winds stripped this weak layer away on some slopes, but certainly not all. On Sunday, Eric and I found that it’s alive and well around Mount Blackmore (photo). Given the large snow load, buried weak layer and recent winds, the avalanche danger is rated CONSIDERABLE.
The Madison and southern Gallatin Ranges, the Lionhead area near West Yellowstone, the mountains around Cooke City and the Washburn Range:
From Big Sky to West Yellowstone to Cooke City, the new snow buried a weak layer of facets that formed on the snow surface 10 days ago. This layer is now under varying depths: 8 inches in the Lionhead area to over 20” outside Cooke City. A natural avalanche on Fan Mountain on a wind-loaded slope, coupled with smaller avalanches in Beehive Basin illustrates this instability around Big Sky. Mark and I got a slope to collapse and crack on this layer in Lionhead, and we found this weakness to be widespread (video) (photo). This layer is easy to find. Simple hands pits uncover it. Riding around we found that slopes touched by the wind cracked and small pockets avalanched. Around Cooke City there was minimal avalanche activity with the new snow, but we know the recipe for avalanches is the same as elsewhere: soft slabs of snow capping a weak layer. For today, given the increasing winds and lots of snow available for loading, the avalanche danger is CONSIDERABLE on all wind-loaded slopes steeper than 35 degrees. All other slopes have a MODERATE danger.
Mark will issue the next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations, drop us a line at mtavalanche@gmail.com or call us at 587-6984.
9th ANNUAL KING AND QUEEN OF THE RIDGE
The 9th Annual King and Queen of the Ridge will be held at Bridger Bowl this Saturday, February 12. ALL proceeds go to the Friends of the Avalanche Center who use the money to promote avalanche education in southwest Montana. You can help raise money to continue this education in two ways: 1). Get pledges and hike the ridge. You don’t have to do 20 laps – you can get flat pledges and hike just once! 2). Sponsor someone. If you don’t have someone to sponsor, consider sponsoring the GNFAC since we’ll be hiking for dollars. Go to http://bridgerbowl.com/events/view_event/81/ for more information and registration forms.
Avalanche Education
TONIGHT in Bozeman
Lucas Zukiewicz-NRCS, from the Montana Snow Survey will present information about the SNOTEL system in Montana, and how to gather and interpret SNOTEL information for backcountry avalanche conditions and travel planning. This free lecture will be held at the REI on 19th Street, from 6:30 p.m. to 8:00 p.m. More info can be found at: http://www.rei.com/event/16591/session/20368
TONIGHT in Butte
Dale Gullett will present a one-hour avalanche awareness lecture at Redline Sports at 7 p.m.
For additional information and a listing of other avalanche classes, go to: http://www.mtavalanche.com/workshops/calendar