Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Saturday, February 13, at 7:00 AM. Today’s advisory is sponsored by Spark 1 and Mystery Ranch. This advisory does not apply to operating ski areas.
Over the past 24 hours no new snow has fallen. At 4 a.m. mountain temperatures range from the mid-20s to low 30s F under partly cloudy skies. Winds are blowing 15-25 out of the west with a few ridgetop gusts reaching over 30 mph. Today, clouds will increase as a weak pacific storm system moves into the area. Valley rain and mountain snow will develop by mid to late afternoon. Temperatures will warm into the mid to upper 30s F and winds will continue to blow 20-30 mph out the west. Snow accumulations of 1-3 inches are likely in the mountains by tomorrow morning.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
Unseasonably warm temperatures have helped overall stability, but have deteriorated skiing and riding conditions. Before yesterday’s 1-2 inches of high density snow, Big Sky Ski Resort closed the tram due to firm-slide for life conditions. Today, I expect a stout melt freeze crust to exist on all but upper elevation, north and east facing slopes.
On slopes where a surface curst does exist it will be difficult to impact weak layers buried mid pack and near the ground, plus you won’t want to ride these slopes anyway. This will make human triggered avalanches unlikely. However, if temperatures warm enough to break the curst down it will be possible for skiers or riders to trigger both loose snow and slab avalanches in steeper terrain. On Thursday, Alex made a video in Cooke City pointing out a few different layers to watch out for on south facing slopes (video, photo).
On upper elevation, north and east facing slopes dry, powdery snow still exist. In these areas it remains possible for skiers or riders to trigger an avalanche on faceted layers buried mid pack and near the ground (photo). While the likelihood of triggering a slide on deeper weak layers is quite low, the consequences remain high. Areas to watch out for will be slopes with a shallower snowpack, primarily those in steep-rocky terrain or slopes that have already avalanched.
Increasing clouds and wind will help keep the wet snow avalanche danger to a minimum today. However, there is the potential for wet snow avalanches to occur in steep, lower elevation terrain where the snowpack has gone isothermal. This hazard poses the most significant threat on slopes with terrain traps such as steep creek beds or gullies.
Today, human triggered avalanches are possible on slopes steeper than 35 degrees which have a MODERATE avalanche danger. Less steep slopes have a LOW avalanche danger.
I will issue the next advisory tomorrow morning by 7:30 a.m. If you have any snowpack or avalanche observations to share, drop us a line at mtavalanche@gmail.com or leave a message at 587-6984.
Darren Johnson Avalanche Education Memorial Fund
The National Avalanche Foundation set up an education fund in memory of Darren Johnson, the Yellowstone Club ski patroller who died in an avalanche on January 19. You can check out details and make donations here: http://www.mtavalanche.com/sites/default/files/NAF%20Darren%20Johnson%20Memorial%20Fund.pdf.
EVENTS and AVALANCHE EDUCATION
A complete calendar of classes can be found HERE.
West Yellowstone: Saturday, February 20, 7-8 p.m., 1-hr Avalanche Awareness for Snowmobilers at the Holiday Inn.
Bozeman: Wednesday, February 24, 6-7 p.m. 1 hr Avalanche Awareness, Roskie Hall, MSU