Photos

From email: "Lots of collapsing and cracking throughout the day. At least a dozen big collapses for me (more than 25' in diameter). Most collapsing was on lower and mid-elevation solar aspects, but some collapses were on mid-elevation northerly terrain today too." Photo: B. Fredlund

Strong wind over the weekend deposited fresh drifts, about 10" deep, over weak snow. Bridger Bowl ski patrol triggered a few of these drifts on Monday (12/21) during avalanche mitigation. Photo: BBSP

We observed two natural avalanches that likely failed 2-3 days ago in the Sunlight Basin in the Taylor Fork. They broke ~150-250 feet wide and ran 250 vertical feet. Photo: GNFAC

We observed two natural avalanches that likely failed 2-3 days ago in the Sunlight Basin in the Taylor Fork. They broke ~150-250 feet wide and ran 250 vertical feet. Photo: GNFAC

This avalanche released while we were across Astral Lake digging snow pits today. South aspect 9500'. Approximately 18" storm total this weekend by yurt.  Only found new snow instabilities in our stability tests this weekend. HS around yurt zone 160-180 cm. Photo: B. Zavora

We remotely triggered (from 30' away) this avalanche at Ski Hill in the Lionhead area. These are red-flags! Stay off of and out from under steep slopes until the avalanche conditions improve. Photo: GNFAC

We triggered this avalanche from 50 feet away. We were walking on a low-angle slope, collapsed the slope, and where the pitch got steeper, we had an avalanche. This is an obvious sign of dangerous instability. If you are on steep slopes it is LIKELY that you will trigger an avalanche. Today, we triggered two avalanches. Photo: GNFAC

A skier kicked off a larger than expected cornice as they skinned up the ridge on the W side of Beehive basin on Sunday (12/20/20).

A skier kicked off a larger than expected cornice as they skinned up the ridge on the W side of Beehive basin on Sunday (12/20/20).

From obs.: "Kicked off a larger than expected cornice as we skinned up the ridge on the W side of Beehive basin. Wind was blowing 20-ish across the opening, cornice had grown pretty good-sized for so little snow. I was making a turn on skins to get back away from the edge when the cornice gave way, probably pulled 25 feet end to end and broke a good 5 feet back from the lee edge of the cornice. I was able to get off the cornice and avoid going over the edge. No activity on the slope below after cornice drop,... although there was a decent hard slab that pulled out just below the ridge when the cornice dropped onto it.... Hard slab on the edges was about 10" deep, some big chunks of cornice on the slope for any future riders..."

Natural slide off lower Hyalite Peak. Photo: H. Van Denburg

Snow plow triggered slide near Big Sky on 12/18/20.

Photo: A. Meng

From email on 12/18: "The avalanches looked to be about 36 hrs old, and were found on N/NE and SE aspects.  About 5 avalanches were observed in total.  Very minimal wind effect in regards to the avalanches, and the landscape in general.  The avalanches were all about 30-40cms deep, and a couple were over 100' wide.... The weak layer was a layer of 2mm facets that formed beneath a m/f crust."

Photo: B. Fredlund

Recent small snowmobile triggered slides along the Big Sky trail in the Cabin Creek area. Photo taken 12/18/20.

Photo: J. Norlander

Small slides on road cuts along the Big Sky trail triggered by the groomer on Thursday night (12/17/20).

Photo: M. Global

The Upper Yellowstone Snowmobile Club worked with the Friends of GNFAC to install two new Beacon Checkers near Cooke City. One is located on the north edge of town as you leave on Miller Rd. The second is at the intersection of Lulu Pas Road and the road to Round Lake. Photo (and assembly): B. Zavora

**Please note, these checkers are not a substitute for formal daily transceiver checks with your entire group. They are there as a reminder. It is important to ensure all of your group member's transceivers have full batteries, and their transmit and search functions work properly.

The Upper Yellowstone Snowmobile Club worked with the Friends of GNFAC to install two new Beacon Checkers near Cooke City. One is located on the north edge of town as you leave on Miller Rd. The second is at the intersection of Lulu Pas Road and the road to Round Lake.

**Please note, these checkers are not a substitute for formal daily transceiver checks with your entire group. They are there as a reminder. It is important to ensure all of your group member's transceivers have full batteries, and their transmit and search functions work properly. Photo (and assembly): B. Zavora

Doug intentionally triggered this wind-loaded sidehill. Weak, faceted snow broke under a 1' deep soft slab of windblown snow. Small avalanches like this are indicators of instability on bigger slopes. These conditions can be found throughout the southern Gallatin, southern Madison, Lionhead and Centennial Ranges. Photo: GNFAC

We observed a cluster of relatively small, loose snow avalanches in the Tyler's Slide area of Beehive Basin. We don't have the recipe for slab avalanches... yet. Wind-loading and/ or new snow could tip the scales. Both are coming this week and next, so stay heads-up! Photo: GNFAC

Small, loose snow avalanche in the Divide Cirque in Hyalite Canyon. These could push a skier into/ off obstacles such as trees and cliffs. Photo: GNFAC