Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Monday, December 12th at 7:00 a.m. Today’s advisory is sponsored by Spark R&D and Yellowstone Club Community Foundation. This advisory does not apply to operating ski areas.
AVALANCHE FATALITY
Yesterday afternoon a skier was killed in an avalanche on Henderson Mountain outside Cooke City. The avalanche was reported to be upwards of 6 feet deep and 100 feet wide and ran through timber. The victim was completely buried and located with an avalanche transceiver by members of his party. One other skier was partially buried, but uninjured. The victim was dug up within 15 minutes and given CPR, but resuscitation was unsuccessful. Doug and Eric will investigate the avalanche today and write a full report in the coming days.
Our condolences go out to his family and friends.
Since yesterday morning the mountains near Big Sky and Cooke City received 3-4” of new snow, other mountains in our area got 1-2” of snow, and the Bridger Range did not get any new snow. Temperatures this morning are in the single digits to low teens F. Wind has been out of west-northwest at 15-25 mph with gusts between 30-50 mph. Westerly wind will continue today at 25-30 mph. Temperatures will be reminiscent of last week with highs in the low teens F. The mountains will get 1-2” of new snow by tomorrow, with more near Cooke City.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
The mountains throughout our advisory area have 2-4 feet of snow resting on a weak layer of facets near the ground (photo, video, video, video). Heavy snowfall and strong wind over the weekend pushed this weak layer to its tipping point, and many large avalanches were triggered. On Saturday, a snowmobiler was caught and fully buried in an avalanche in the second Yellowmule on Buck Ridge; and yesterday, a skier was buried and killed in an avalanche near Cooke City.
Over the weekend, ski patrols triggered deep avalanches that ran long distances into flat terrain, and broke on the weak facets resting over a hard crust on the ground (photo, photo, photo). These avalanches were triggered with explosives, but smaller triggers cannot be ruled out. A natural avalanche was reported on the north face of Mt. Blackmore and likely broke on these weak facets as well. Today, large avalanches are possible to trigger by the added weight of a skier or rider, or a smaller avalanche that breaks deeper into the snowpack.
Wind gusts of 50 mph were recorded over the past two days. These strong winds dirfted snow into slabs that could release as small avalanches on their own, or trigger a deeper avalanche. Avoid steep wind loaded slopes and practice cautious route selection. The avalanche danger today is CONSIDERABLE.
Doug will issue the next advisory tomorrow morning at 7:30 a.m.
We rely on your field observations. Send us an email with simple weather and snowpack information along the lines of what you might share with your friends: How much new snow? Was the skiing/riding any good? Did you see any avalanches or signs of instability? Was snow blowing at the ridgelines? If you have snowpit or test data we'll take that too, but this core info is super helpful! Email us at mtavalanche@gmail.com or leave a message at 406-587-6984.
BOZEMAN
15 December, Avalanche Awareness and Beacon Practice, 6-8 p.m. at Beall Park.
WEST YELLOWSTONE
15 and 16 December, Snowmobile Introduction to Avalanches w/ Field Day, West Yellowstone Holiday Inn Conference Hotel. More info and sign up HERE.
COOKE CITY
Every Friday and Saturday, Weekly rescue training and snowpack update, Super 8 on Friday 6-7:30 p.m. and field location TBA for Saturday.
BILLINGS
15 December, Snowmobiling In and Identifying Avalanche Terrain, 6-8 p.m., Big Horn Resort.