Island Park

In the Taylor Fork area of the Southern Madison Range, a group of three riders remotely triggered an avalanche on a nearby slope that broke nearly a mile wide. Dangerous avalanche conditions exist due to the threat of large slides failing on weak layers near the ground. Avoid being on or immediately underneath these slopes. Play on slopes less than 30 degrees in steepness with nothing steeper above you.

There were a couple of spectacular avalanches yesterday. Cooke City produced a slide on Scotch Bonnet that broke 8 to 12 feet deep and 1300’ wide (details and photo). In the Taylor Fork area of the Southern Madison Range, a group of three riders remotely triggered an avalanche on a nearby slope that broke nearly a mile wide (details and photos).

Persistent weak layers of sugary facets at the base of the snowpack have been trembling and cracking under the weight of recent snowfall, resulting in persistent slab avalanches. This structural flaw is present on nearly all middle- and upper-elevation slopes.

Additionally, winds are drifting snow onto slopes, where wind slab avalanches can break, catch, and bury riders or skiers. Wind-loaded slopes are often those immediately below ridgelines and in upper-elevation gullies, with instability indicated by avalanches and shooting cracks.

Persistent slab and wind slab instability are the commonalities. The differences result from the:

1. Amount of recent snowfall and wind (weather log)
2. Depth of snowpack, a proxy for the potential size of an avalanche (weather stations and SNOTEL Sites)
3. Observed instability (avalanche activity list).

Dangerous avalanche conditions exist in the Cooke City Area, with HIGH danger on upper-elevation wind-loaded slopes. In the last week, feet of snow containing 7” of snow water equivalent fell, loading the snowpack to failure. Yesterday, local guides reported additional slides on Republic Mountain, Sheep Mountain, and Henderson Mountain. On Monday, a group triggered a large wind slab avalanche from a safe position nearby. Avoid slopes steeper than 30 degrees and the runout zones below.

In the Madison and Southern Gallatin Ranges and the Lionhead and Island Park Areas - The avalanche danger is CONSIDERABLE at middle- and upper-elevations, where winds continue to load slopes during the break in snowfall. Another snowmobiler-triggered avalanche in the South Madison Range broke as wide and deep as the slope allowed (details and photo), and in my video from Lionhead, I discussed how it is easy to trigger weak layers. Avoid travel on or immediately below steep slopes with weak basal layers. Watch Ian’s video from Buck Ridge and my video from the Taylor Fork.

In the Northern Gallatin Range, strong winds are building unstable drifts at middle and upper elevations that could be large enough to bury or injure a skier or rider, and the danger is CONSIDERABLE. Seek out terrain sheltered from wind-loading and evaluate the snowpack for instability related to buried weak layers before considering steeper terrain. Avoid wind-loaded slopes. 

With less recent snow and avalanche activity, the danger in the Bridger Range is MODERATE. Seek out smaller, lower-consequence terrain free from terrain traps after evaluating the snowpack for instability related to persistent weak layers and wind loading. See recent videos from Saddle Peak and the Ramp.