Trip Planning for Southern Gallatin

From 5/21/22: "Triggered a small slide underneath the cornice of the southeast chute off of Emigrant peak. The slide was 50 ft wide,  4 inches deep, and ran for about 100 ft. The slide was not large enough to knock you off your feet (D1). The latest storm had deposited about 12 inches of new snow underneath the cornice." Photo: C. Chupik

Natural avalanche that occurred at Bridger early on 5/9/22. There were many similar depth natural crowns along the ridge that broke within the recent snow that fell over the weekend.

Crown of a natural avalanche that occurred at Bridger on 5/9/22. There were many similar depth natural crowns along the ridge that broke within the recent snow that fell over the weekend.

Obs 5/9/22: "found an intact graupel layer buried by 10-14” of fresh snow. Got cracking on it (ectn 17, ct 18) but no propagation. Also saw lots old of storm slabs/wind slab crowns."

Natural wet loose avalanche in Beehive Basin. Occurred on Wednesday 5/4 after new snow fell on Tuesday.

Wet loose snow avalanches of recent 6" of snow. They likely occurred when the sun came out Wednesday morning, or at the end of the storm on Tuesday. GNFAC

"5/3/22 at approximately 4:00pm a storm slab avalanche occurred in beehive basin on a west aspect @9000 ft. This slab was 6-8” deep and propagated around 50’. No one was buried, however we aren’t sure if anyone was caught because we were not the party who triggered this avalanche. We did witness the party drop in but quick went out of sight." Photo: H. Bigos-Lowe

Skiers reported shooting cracks from their skis while ascending the terrain at Bridger Bowl. The group later remotely triggered an avalanche from 100'+ away that ran through the "Pearly Gates" and "Patrol Chute". 

On 4/18/22 near Cooke City we witnessed natural rollerballs and pinwheels by 11 am, and a couple wet loose slides below cliffs on southerly slopes around noon, and were able to easily trigger pinwheels on west-southwest aspects around 1230-1pm. Photo: GNFAC

A large drift on the Ramp just north of Bridger Bowl. Photo: GNFAC

Drifts cracked and slid on steep rollovers north of Bridger Bowl. Photo: K Hammonds

An avalanche on Wilson Peak that caught two skiers and injured one on 4/3/22. Photo: GNFAC

On 3/27/22 Big Sky ski patrol witnessed many natural wet slides in closed terrain. Photo: BSSP

"We also conducted avalanche mitigation on our Cabin’s Road at 4:30pm. The snowpack in this zone doesn’t get skied and is representative of the backcountry. The slope is ENE around 8,400’. Several wet slab avalanches were produced with explosives and ski cutting. The avalanches ranged from R4/D2 to R2/D1. They all hit the road and several crossed, and buried, the Cabin’s Road. Although most of this mitigation was done with explosives, it took minimal effort with skis to get snow moving. The crowns were 2-3’ deep and ran on the ground." Photo: YCSP

"A wet loose avalanche was seen in the Apron (closed terrain that hasn’t been opened this season) around 3:00pm. It was an R2/D2 on a east facing slope around an elevation of 8,500’." Photo: YCSP

Natural wet slab avalanche on Cedar Mtn. Observed 3/26/22. Photo: J. Gerardi

Natural slab avalanche on the Sphinx. Observed 3/26/22. Photo: J. Gerardi

From obs 3/26/22: "Freezing temps overnight created breakable crust in the morning which quickly deteriorated as the day warmed. (Temps rose surprisingly faster than we anticipated.  Experience large whumphs while ascending the NW shoulder of Electric Pk. at 9600 ft. Without hesitation we turned back and skied out the skin track. The snow became very rotten and we penetrated to boot-tops often while exiting." Photo:  S. Miller

On March 26 many natural wet slides occurred in closed terrain at Bridger Bowl. Photo: BBSP

We saw this natural avalanche on 3/19/22 appeared to be within 24 hours old and triggered by cornice fall that broke out a slab below. Northeast aspect at 8,800' on Lionhead Ridge. Photo: GNFAC

Wet slides occurred near Quake Lake on 3/3 or 3/4. Photo. T. Hansen

From obs 2/27/22: "Shooting cracks in a thin wind slab on a ridge crest. The slab was small but the collapse was abrupt and propagated 20 feet." Photo: J. Taylor

From obs. 2/27/22: "Shooting cracks in a thin wind slab on a ridge crest. The slab was small but the collapse was abrupt and propagated 20 feet." Photo: J. Taylor

"[Natural] Avalanche on the south side of Cabin Creek filled the creek and up the opposite bank." Appeared to be up to a week old. Photo: T. Sizemore

This is the slope that avalanched and killed a snow bike rider (motorized) on 2/19/22. Photo is from the Search and Rescue team who were leaving the site as it was getting dark, and did not have time to gather more info. Click link below for more details. Photo: B. Zavora

We saw this fairly recent, very small cornice fall avalanche on Cedar Mtn. on 2/12/2022. Photo: GNFAC

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

Looking up from the bottom of the avalanche that killed one snowmobiler on Ski Hill. The crown is visible at the top of the hill. The men in the photo are standing near the trees where the victim was buried. 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

A small, skier-triggered avalanche on Mt Blackmore on Sunday (Feb 6) would be unlikely to bury a skier or rider, but could push them into or off obstacles. Photo: E Stutzman

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

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