Good morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued Friday, December 13 at 7:30 a.m. A Montana FWP Recreation Trails Grant sponsors today’s advisory. This advisory does not apply to operating ski areas.
Temperatures this morning were mostly in the mid to high teens F with winds blowing 10-15 mph from the W and SW gusting to 20 mph. Today will be cloudy and some snow will fall but only an inch or two will accumulate. Temperatures shouldn’t warm much and winds will shift a little through the day towards the NW blowing 10-15 mph gusting 20-30 mph.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
Last week extreme cold temperatures weakened the snowpack. This week cold weather ended, snow fell, and the wind blew - a perfect combination for avalanches. Many occurred during the last few days. See photos of these recent slides here. A skier near Hyalite Peak found at least 5 recent avalanches on wind loaded slopes including one that may have been triggered by a mountain goat. Yesterday there was only one reported avalanche that a skier triggered on a heavily wind loaded, S facing slope on Ross Peak in the Bridger Range (photo).
Yesterday Doug and Eric went to Hyalite near some popular ice climbs (video). They didn’t think avalanches would be occurring on their own but could definitely be triggered by a climber or skier (or even a goat). The reason is that the structure and layering of the snowpack has not changed. In many places a hard slab of wind-blown snow rests on very weak facets.The problem with ice climbing is that any slide, even very small ones, can be deadly.
On Wednesday, my partner and I remotely triggered avalanches on Buck Ridge (video). A skier remotely triggered a slide near Cooke City on Tuesday. These slides are ones triggered from some distance away on low angle slopes. Remotely triggered avalanches indicate very unstable conditions. Things may not be as sensitive today, but I would not trust the snowpack. In many places the snowpack has fresh wind slabs on top and weak, facets near the bottom. Neither should ever be trusted alone. Together they make the perfect recipe for human triggered avalanches.
Today the avalanche danger is CONSIDERABLE on all wind loaded slopes where human triggered avalanches are likely. Slopes without a wind load have a MODERATE danger but should still be approached with caution.
Eric 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
BUTTE: Today, 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. NO registration required. Just show up.
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