Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, March 1, at 6:30 AM. Today’s advisory is sponsored by Yellowstone Ski Tours and the Community Food Co-op. This advisory does not apply to operating ski areas.
There’s been no new snow in the last 24 hours, but gusty winds yesterday morning topped 60 mph at the ridgetops. This morning, west winds are averaging 20 to 30 mpg under clear skies with mountain temperatures of 10F. Clouds will increase today and temperatures will warm into the 30s. Tonight winds will increase from the southwest at 20-40 mph and 1-2 inches of snow is expected by morning.
Southern Madison Range Southern Gallatin Range Lionhead area near West Yellowstone Cooke City
Yesterday was a windy day with gusts of 60+ mph blowing from all directions. The 6-8 inches of snow that fell in the southern mountains since Sunday morning got blown around at all elevations (photo). There’s been no avalanche activity reported and the wind slabs are bonding well. Buried 1-2 feet under the snow surface is a layer of feathery surface hoar crystals (video, photo). Although every mountain range south of Big Sky has them, they are not found on every slope. This variable distribution means you have to dig down to see if they are present. If they are, ski or ride elsewhere as slopes with surface hoar can avalanche.
The last signs of instability were on Friday when Eric got cracking and collapsing at Bacon Rind. Fresh wind slabs and a layer of buried surface hoar are keeping the avalanche danger MODERATE since it’s still possible to trigger slides today.
Bridger Range Northern Madison Range Northern Gallatin Range
In the northern mountains the snowpack is mostly stable. Eric found consolidated snow in his pits on Buck Ridge on Sunday (photo) and spoke about fresh wind slabs forming from winds in his video. I saw plumes blowing off the ridges up Hyalite on Sunday and the Big Sky Ski Patrol found a few 1-foot deep wind slabs during avalanche control yesterday that would only release with explosives. Because of the strong, swirly winds, wind slabs are not confined to the ridgelines. Most of these slabs will be unmovable and stable, but a few steep pockets could be triggered. These conditions are reminiscent of the avalanche that killed a skier on Beehive Peak last April: a relatively stable snowpack with isolated pockets of wind slabs above cliffs.
For today, avalanches are unlikely and the danger is rated LOW.
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.
EVENTS and AVALANCHE EDUCATION
A complete calendar of classes can be found HERE.
Bozeman: Wednesday, March 9, 6-7 p.m. 1-hr Avalanche Awareness, REI.