Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued Wednesday, December 11 at 7:30 a.m. Grizzly Outfitters in partnership with the Friends of the Avalanche Center sponsor today’s advisory. This advisory does not apply to operating ski areas.
The Bridger Bowl Cloud was in full force yesterday and dropped a total of 26 inches! Put the kids in daycare, call in sick, skip school and shred. This is why we live here, right? All other mountain ranges picked up 2-4 inches yesterday. Winds are still blowing at 20-30 mph, but the direction has switched from west to southwest. This morning is clear with mountain temperatures in the single digits, but this afternoon temperatures will rise into the 20s under partly cloudy skies. Winds will continue to be moderate out of the southwest and no precipitation is expected in the next 24 hours.
Northern Gallatin Range
Yesterday Mark and I went up Hyalite to scope out avalanche conditions for this week’s Ice Festival. What we found was not pretty. Hard slabs of windblown snow are sitting on large faceted grains and are very easily triggered. There were many avalanches yesterday: we kicked off the hangfire of a slide by the Dribbles (video, photo), a climber was almost swept off the Fat One (photo) and other climbers triggered slides and had shooting cracks throughout Hyalite and Flanders. We also had a slab of ice fracture on facets at Mummy 2, the first time I’ve ever seen anything like it (video, photo, photo), which we took as a serious warning. If the facets are weak enough to collapse and propagate a fracture under ice, wind slabs don’t stand a chance!
My advice is to stay away from all the gullies since they have wind-loaded snow that will very likely avalanche. Be careful climbing underneath them and be especially wary about triggering a slide onto someone below. Small avalanches that would be inconsequential to a skier are fatal to an ice climber. Outside of the ice climbing zone, the snowpack in Hyalite is deeper and more stable, but today’s winds will continue loading slopes at the higher elevations. The avalanche danger today is HIGH on all wind-loaded slopes and CONSIDERABLE on all others.
Bridger Range
The Bridger Range got walloped with over two feet of snow and ridgetop winds. This is a large load with wind slabs adding even more stress to the snowpack. I expect a few natural avalanches on wind-loaded terrain, and if folks are not careful, human triggered ones too. Lots of new snow plus wind will keep the avalanche danger at CONSIDERABLE on all wind-loaded slopes. Slopes without a wind-load will have a MODERATE danger. Moderate danger means human triggered avalanches are still possible so keep your powder enthusiasm in check.
Madison Range Southern Gallatin Range
Lionhead area near West Yellowstone Cooke City
The other mountains received the same winds, but only 4-8 inches of total snow over the last 36 hours. Weak snow exists about a foot off the ground in the southern Madison Range and around Big Sky. Outside Cooke City a skier remotely triggered a slide one to three feet deep. Wind slabs are the issue. Thick, meaty slabs of windblown snow have added stress to the snowpack. Slopes with weak facets will likely be triggered today. Besides digging snowpits and doing stability tests, pay close attention to collapses and cracks shooting out from your skis or snowmobile. These are bull’s eye data that the snow is ripe to avalanche. For today the avalanche danger is rated CONSIDERABLE on all wind-loaded terrain and MODERATE elsewhere.
Mark 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.
EVENTS/EDUCATION
BOZEMAN: Wednesday, December 11, 7 p.m., International Mountain Day, Emerson Cultural Center, Avalanche Forecasting and Awareness. http://www.mtavalanche.com/images/13/international-mountain-day
FOUR CORNERS: Wednesday, December 11, 7 p.m., 1-hour Avalanche Awareness for Snowmobilers at the GVSA Groomer Shed, http://gvsa.net/
BUTTE: Friday, December 13, 5-6 p.m. 1-hour Avalanche Awareness for Snowmobilers at the Depot Theater in Butte. This is the Thunderstruck Premier. Call Jeff at 406-560-0897 for more info.
BOZEMAN: Saturday, December 14, 10:30-11:30 a.m. Free Avalanche Transceiver Workshop, Bridger Bowl, next to the rental shop at Jim Bridger Lodge.
GARDINER: Thursday, December 19, 7-8 p.m. Avalanche Awareness, at the Yellowstone Association in Gardiner. Call Zachary for more info at: 406-848-2850.
WEST YELLOWSTONE: Snowmobiler Intro to Avalanches w/ Field Course; 19 and 20 December. Info and registration: https://www.ticketriver.com/event/7116