Trip Planning for Southern Madison

Chris Hericks, snow ranger on Beaverhead Deerlodge NF, points to the lower of two surface hoar layers. We are finding similar layering throughout our entire forecast area. The top 18" of the snowpack is weak and will quickly become unstable when it snows. Photo: GNFAC

The crown is not visible (it is down and right) but the X marks the approximate spot the rider was found. Photo: GNFAC

The crown was measured 4-11 inches deep and 75 feet wide. Photo: GNFAC

Looking at a weak layer of facets that the avalanche propagated on. Photo: GNFAC

Looking at the crown from below. Photo: GNFAC

On Sunday, February 6, Gallatin Country Sheriff Search and Rescue and the GNFAC responded to a avalanche in Lionhead. A snowmobiler was killed on a small steep slope when a shallow avalanche carried him into a terrain trap of trees. Photo: GNFAC

This morning while ascending a line on Sawtooth Mountain (Lower Novocain) we triggered an avalanche (ASu-SS-R2-D2-O)  that caught and carried my partner an estimated 180M and partially buried him. His leg and hand were unburied and excavation of the head was done in less than 2 minutes of the incident. The avalanche only involved new snow from the last 48hrs and was triggered on a MF crust/facet combo 30cm down(formed 1/30/22). The avalanche was 30cm at its deepest and 20-30M wide and ran 250M. We were lucky to find both skis and poles a little ways downslope. No injuries were sustained.

We both agree that we were trying to outsmart the instability that was present on steeper S facing terrain and should have turned around much sooner, we were very lucky. There was 30+cm HST in favored areas and the high winds from 1/31/22 formed some sensitive windslabs in specific areas. 

Graph of Snow Water Equivalent (SWE) at SNOTEL sites in the GNFAC forecast area from October 1, 2021 to January 30, 2022. It highlights the extended dry conditions in January that contributed to weak layers forming at the top of the snowpack. GNFAC

A layer of surface hoar that was buried by the recent snow in the southern Madison Range. Photo (1/22/22): G. Turnage

A group at Ernie Miller Ridge had an unstable test score in their second snowpit of the day (1/16/22). Lingering instabilities are isolated but it is an excellent idea to dig down and test the snowpack before getting into avalanche terrain. Photo: T Dumbrovsky

Riders reported on 1/15/22: "Some surface hoar is forming on nearly every aspect at all elevations. over 1 cm thick in some areas." Photo: B. Rasmussen

Riders reported on 1/15/22: "Some surface hoar is forming on nearly every aspect at all elevations. over 1 cm thick in some areas." Photo: B. Rasmussen

Settlement rings around the base of trees near Cooke City, January 15, 2022. Photo: B. Fredlund

Seen 1/14/22, R1-D2 on west aspect at 9,500'. Photo: GNFAC

Avalanche that is likely 5-7 days old in Sunlight Basin, Taylor Fork, southern Madison Range. Photo taken 1/14/22 by GNFAC

Avalanche that is likely 5-7 days old in Sunlight Basin, southern Madison Range. Photo taken 1/14/22 by GNFAC

Avalanche that is likely 5-7 days old in Taylor Fork, southern Madison Range. Photo taken 1/14/22 by GNFAC

Avalanches on Red Mountain. Photo taken 1/13/22. Likely broke around 1/8/22. Photo: M. Standal

A group in Cabin Creek saw a very large crown from an avalanche that occurred on the east aspect of Sage Peak last weekend (1/7 or 1/8). Photo: Anonymous

From email 1/9/22: "Skier triggered cornice failure avalanche. Broke at skis 10-12 feet from the lip. No one caught or injured."

From email 1/9/22: "Skier triggered cornice failure avalanche. Broke at skis 10-12 feet from the lip. No one caught or injured."

A sled was recovered uphill of the 2 avalanche victims in the same area it was stuck. The sled was found with a probe line and is buried 3-4 feet deep. The avalanche crown can be seen in the upper slopes above them. Photo: GNFAC

The crown of the avalanche that killed two snowmobilers on December 27, 2021 was 300 feet wide and 4-5 feet deep. Photo: GNFAC

These are the two sites where the 2 snowmobilers were recovered. They were buried 4-5 feet deep in debris piles that measured 9 feet deep. Photo: GNFAC

Ian Hoyer stands next to the crown where we dug a snowpit and investigated the snow structure. The crown averaged 4-5 feet deep. Near his right knee is the layer of weak faceted snow that broke 40 cm above the ground. Above this layer was a thick slab of windblown snow. Photo: GNFAC

Dave Zinn of the GNFAC gets 3 layers breaking in his Extended Column Test. About 3 feet of snow fell in the last 4 days which got blown into wind slabs. The weight of the new snow is also creating instability on a weak layer of sugary facets near the ground. Photo: GNFAC

Bare ground on the ridge between Tepee Basin and Bacon Rind Creek. Nearby we found 4 ft deep drifts. 12/22/21. Photo: GNFAC

An avalanche in Tepee Basin appears to have failed within or under the new snow around 12/15/21. Photo taken 12/22/21.

Photo: GNFAC

An avalanche in Tepee Basin that broke under new snow on facets near the ground. Likely occurred on 12/15/21. Photo taken 12/22/21.

Photo: GNFAC

Digging a snowpit in 4 feet of drifted snow in Tepee Basin (12/22/21). Photo: GNFAC

Natural avalanche in Taylor Fork that broke 100ft wide, 2-3 ft deep, beneath the recent storm snow. Appears to have failed towards the end of the storm (likely 12/15/21). Photo: GNFAC

This avalanche was remotely triggered by snowmobilers from over 100 ft away on 12/15. It broke beneath the recent storm snow, 1-2 ft deep.

Photo: GNFAC

A skier in the Southern Madison Range remotely triggered this avalanche in the Bacon Rind area from a flat bench above the slope. It broke over 50-75' away where the slope got steeper. Human-triggered avalanches are likely. Avoid steep terrain until the snowpack stabilizes. Photo: Anonymous 

From obs: 12/12/21: "Heavy wind loading from gusty SW winds and recent snowfall. Made for some touchy conditions. This was at 9100’ between Sage and Sunlight basins." Photo: JR Mooney

New snow was blown into thick drifts that can be triggered by skiers or riders. Cracking like this is a sign that drifts are unstable and could slide on steeper slopes. Photo: GNFAC

From obs (12/5/21): "Went poking around in the Taylor Hilgard today looking for snow. As expected, found a thin and faceted snowpack at lower elevations. Snowpack improved considerably above 8500', often .5-1m. I dug a quick pit to the ground on a N-NE facing slope at around 9300'. Pit measuded 1.1m, and to my surprise consisted of a relatively compacted and consolidated snowpack, almost entirely 4f hardness. I was expecting to find layers of facets near the base of the snowpack, and between crusts in the middle, but did not."

Photo: L. Heine

From email (12/5/21) : "Small avalanche triggered while approaching ice climb in East fork of Hyalite basin. 

Another D1 natural avalanche was observed later in the day similar aspect/elevation

NE @7600’
SS-AFu-D0.5-I"

Photo: A. Schoening

Skiers on Mount Blackmore observed cracking within the freshly wind-loaded snow on a southeast-facing slope just below the ridge (11/24/21). Photo: J Schack

From e-mail 11/7/21: "...Once in airplane bowl we saw multiple large slides that ran last night, syn-storm. Most of which came down from the East face of Sac. A few 200-300’ wide and running the length of the bowl.,,, attached is a grainy cell phone pic of the slides in Airplane Bowl." -Anonymous.

From email 11/4/21: "...noticed two small wet loose avalanches in the east facing bowl between Pomp and Hardscrabble Peaks." Photo: H. Darby