Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, December 29, at 7:30 a.m. Today’s advisor is sponsored by Cooke City Super 8/Bearclaw Bob’s and Community Food Co-op. This advisory does not apply to operating ski areas.
Last night the mountains around Cooke City picked up 1-2 inches of new snow with the rest of our area getting a trace. Temperatures are near 10F this morning with light east to north winds blowing at 5-10 mph. Today will be partly to mostly cloudy, winds will be calm and temperatures will rise into the mid-20s. Light flurries will continue today and tonight, but only add up to an inch or two at most. Looking towards the weekend there are no major storms on the horizon.
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke City
Since yesterday morning many avalanches were reported and I added seven photos to our collection spanning Cooke City, the northern Gallatin and southern Madison Ranges. Some of the larger ones occurred outside Cooke City where natural slides were seen in Republic Creek and likely human-triggered avalanches were seen on the NW face of Crown Butte and above Henderson Bench which was a deep, hard slab. All avalanches, here and elsewhere, are breaking at the ground on the sugary snow (depth hoar). Over 50 avalanches were seen from Bozeman to Cooke City by a small plane pilot (Mt. Fox avalanche).
Poor stability is also found from the Bridger Range to Big Sky to West Yellowstone. Instead of listing every occurrence, I encourage you to check out the Daily Weather Log for a list of avalanche activity. Trust me, the snowpack is unstable; avalanches are undeniable proof and every range has had recent activity.
Depth hoar is having a difficult time supporting all the snow weight from last week. As days pass without storms, natural avalanches are subsiding along with tell-tale signs of instability such as collapsing (whumphs) and cracking. In the absence of new or windblown snow triggering slides, the weight of a skier or snowmobiler will do. I outlined this issue in a video, “Should You Ski It?” which also applies to snowmobilers.
The snowpack is no longer hair-trigger. People are boldly venturing onto big, steep slopes with their sleds and skis. Cooke City has more human-triggers per square mile than any other piece of real estate on the forest and I expect we’ll hear of a corresponding number of avalanches too. The other ranges are not immune, yet the stoke of powder is a sirens’ song luring folks into unstable avalanche terrain. For today, the avalanche danger is rated CONSIDERABLE on all slopes steeper than 35 degrees since triggering slides is likely. Slopes less than 35 degrees are rated MODERATE and a scary moderate at that! Be certain that lower angled terrain is not attached to steeper slopes. This recipe killed a snowmobiler 10 days ago.
Good stuff not to be missed:
Eric wrote a great article on Depth Hoar.
Video: “Still bad on Mt. Ellis and everywhere else”.
Video: “Unstable Snow on Mt. Blackmore”.
I will issue the next advisory tomorrow morning at 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.
West Yellowstone: January 2, 1hr Avalanche Awareness, West Yellowstone Holliday Inn, 7-8:30 p.m.
Bozeman: January 6, Women’s Avalanche Awareness and Beacon 101, Beall Park, 6-8 p.m.
January 9 and 10, Companion Rescue Clinic, REI, Fri 6-8p.m., Sat 10a.m.-2p.m.
January 13, 1hr Avalanche Awareness, REI, 6-7:30 p.m.
Livingston: January 14, 1hr Avalanche Awareness, Neptune’s Brewery, 6-7:30 p.m.
Dillon: January 19, 1hr Avalanche Awareness, UM Western Library, 6:30-8 p.m.
ASMSU Intro to Avalanches w/ Field Course
January 20, 21 and 23 or 24: https://www.ticketriver.com/event/16861
The workshops will be held on Wednesday and Thursday evenings, with a field course on either Saturday or Sunday. Different topics will be presented each evening. Topics include: avalanche terrain recognition, the effect weather has on avalanche hazard, the development of the mountain snowpack, decision making skills, and basic search and rescue procedures.