Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, February 16, at 7:30 a.m. Alpine Orthopedics and World Boards sponsor today’s advisory. This advisory does not apply to operating ski areas.
Winter is working hard to make an appearance. Over the past 24 hours most mountain locations picked up 3-5 inches of low density snow with the exception of the mountains near West Yellowstone which picked up around one inch. Temperatures are also the coldest they have been in weeks. At 4 am, mountain temperatures are in the single digits to mid-teens F and winds are light out of N-NW. Today, a northwest flow aloft will continue to produce light snow showers in the mountains, although no real accumulation is expected. Temperatures will warm into the upper teens to mid-20s F and winds will remain light out of N-NW. Winter will try and stick around until tomorrow then spring like conditions return on Wednesday.
Bridger Range Madison Range Gallatin Range
Lionhead Area near West Yellowstone Cooke City
It’s time to hang up the mountain bikes and fishing rods for a day and indulge in a brief taste of winter. Although snow totals are not real impressive, they are enough to improve riding conditions and elevate the avalanche danger.
In the mountains around Bozeman, Big Sky and Cooke City, new snow instabilities are the primary avalanche concern. On all but north facing slopes, the new snow will move easily on top of a firm ice crust. Most avalanche activity will stay confined to loose snow avalanches or sluffs, but there is the possibility of small soft slabs releasing in upper elevation terrain below the ridgelines. Avalanches occurring in the new snow will not be exceptionally large, but may produce enough volume to carry a skier or rider. The danger becomes amplified it you’re skiing or riding in steep, high consequence terrain.
In the mountains near West Yellowstone, the primary avalanche hazard remains a layer of surface hoar buried 1-2 feet deep. Without the stress of new snow, triggering an avalanche on this layer is becoming more difficult. However, I still wouldn’t trust a 35 degree slope where this layer is present. The tricky part about buried surface hoar is its spotty distribution. The only real way to determine if the slope you want to ride has this layer is to put a shovel in the snow and dig a quick a snowpit (video, video, photo). Buried surface hoar typically presents itself as a gray stipe in the snowpit wall. If buried surface hoar shows up in the area you plan to ride, it’s best to keep slope angles on the low side.
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.
Doug 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.
AVALANCHE EDUCATION and EVENTS
Take a look at our Education Calendar for all classes being offered.
Snow Science and the Human Factor, Bozeman, MSU Procrastinator Theater, 6-8:00 p.m., Tuesday, February 17. The free event will feature a talk by Powder editor and MSU graduate John Stifter, multimedia presentations on the human factor in avalanche risk, a panel of experts from MSU’s Snow & Avalanche Lab and Gallatin National Forest Avalanche Center, as well as a Q & A session (poster).
Companion Rescue Clinic, Bozeman, REI, 6-8 p.m., Friday, February 20 and 10 a.m.-2 p.m. on Saturday, February 21 (field location TBD). Pre-registration is required: www.rei.com/stores/bozeman.html
1-hour Avalanche Awareness, West Yellowstone, Holiday Inn, 7 p.m., Saturday, February 21.
Companion Rescue Course for Snowmobilers, Cottonwood Drainage, Crazy Mountains, Saturday, February 21, 9:30 a.m. – 2 p.m. Please RSVP to your club officers or to kathrynjbarker@fs.fed.us if you are interested in participating.