Trip Planning for Northern Gallatin

From Obs 1/23: "While on the ridgeline on the way up we triggered many small wind drifted pockets."

A view of Sacajewea Peak from the Fairy Lake road. Evidence of winds are seen on the right shoulder of the peak. Photo: GNFAC

Slopes on Hardscabble Peak in the northern Bridger Range show bare slopes that got blown clean by wind. Photo: GNFAC

In the northern Bridger Range we dug a pit at 8700 feet on a north facing slope before skiing the chute into the basin. Our stability tests did not break and all evidence pointed to a LOW danger. Photo: GNFAC

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

Looking up at the Fat Maid from Maid of the Mist basin. Strong winds over the last week have scoured the alpine, exposing lots of rock. Photo: GNFAC

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."

It was easy to crack the thin wind slabs that formed from strong wind the last 2 days. They were not propagating, but cracking indicated potential instability on wind drifts. Photo: GNFAC

Strong wind in the previous 2 days sculpted the snow surface into waves of sastrugi. Photo: GNFAC

Wind in the last 2 days gusted 45-70 mph and stripped some starting zones down to dirt in Beehive Basin. Photo: GNFAC

We intentionally triggered this 6-8" deep wind slab on Saddle Peak on December 23, 2021, E aspect at 9,000'. It showed us that recently formed wind slabs were still reactive. This hard slab formed over low density new snow which made it unstable. While not large, these slides will easily push you down and can be harmful if they push you into hazardous obstacles or terrain traps. Photo: GNFAC

Pit from 12/22/21 at 9,850' on the NE face/shoulder of Mt. Blackmore. Snow depth was 111cm, first ECT was ECTN10 below the wind slab then ECTN22 on facets at 70cm. A second test was ECTN17 on that facet layer, then ECTP20 on depth hoar at 35cm. A third ECT was ECTP17 on the facets at 70cm, then a fourth ECT was another ECTP17.... I was moving into shallower snow as I got more unstable results, down to about 90cm HS. These weak layers are not easy to trigger or showing obvious signs of instability, but we will need to be careful when we get more snow, especially during large cumulative loading or big wind events. Photo: GNFAC

North face of Mt. Blackmore on 12/22/21. South-southwest winds were moderate-strong and scouring more than loading it seemed like, but isolated slabs and whales of snow could be found. We did not get any drifts to crack or collapse. Fresh wind slabs were 2-4" thick, 1f-P hard, and not very continuous. Photo: GNFAC

Cornices that formed mid-slope, indicating recent heavy wind-loading in the Bridger Range. Strong southwest wind between 12/18 and 12/19/21 drifted recent snow into hard, pillowy drifts. We avoided these drifts on steep slopes to give them a day or two to stabilize. Photo: GNFAC

These pillowy, hard drifts formed from strong southwest wind overnight between 12/18 and 12/19/21 in the Bridger Range. We saw minimal signs of instability, lke whumphing or cracking in these drifts, but avoided these features on steep slopes until they have more time to gain stability. Photo: GNFAC

From obs 12/18/21: "95cm Snow depth at around 9400’ 40cm of new snow on early December ice crust Ectx18 Will have to see with more loading on early December interface if it becomes reactive All alpine terrain was heavily stripped from the wind."

On 12/16/21 A skier in a group of three triggered and was caught in this avalanche next to The Apron at Bridger Bowl. The ski area is closed and backcountry conditions exist. Nobody was injured.

From e-mail: "We had a group of three skiing up at the Bridger Apron today. We skied a more main slope in the field north of the slope with hidden couloir, snow was very stable and has been getting a lot of tracks. For a second run we skinned up the main slope under hidden and started our run in the trees slightly south of this slope. Not many tracks over there and not a good enough evaluation of the snowpack. We were planning on skiing a northeast facing chute through the trees that had very nice looking snow similar to what we had skiied earlier. I skiied in and had about 3 amazing turns, definitely partially due to the wind loading at this aspect. After three turns my feet were taking out from under me and I got caught in a slide keeping skis perpendicular to slope for 15-20’. This avalanche carried me rapidly and cleared the snow to the rocks below in which I was able to come to a hault and watch the rest of the sluff slide past me. After looking at the conditions after, this windy aspect seemed to have a very faceted layer about 8” down that acted as the crown. No injuries, a lost ski pole in the runout which extended down the slope maybe another 40’. The wind scoop on top and seeing these facets should have been a clear sign prior to skiing. Must be more diligent even in areas of high traffic. When dropping in to ski on first turn or so I remember hearing a possible whumpf."

Skiers up the East Fork of Hyalite Creek observed this small avalanche on a road cut. Photo: S. Reinsel

From IG 12/12/21: @montanamountainmedicine

From obs: 12/12/21: "Shooting cracks and whoomphing in wind loaded areas. An approximately 15x30ft wind slab cracked along the base of a rock band and settled at the base of P2 on high fidelity. Was triggered while traversing along the rock band to gain the second pitch, 1-2 inches of facets on the ground. Wind slab of 6-36in in the gullies." Photo: M. Hearley

In the Bridger Range on December 10, 2021 2-3" of low density new snow was drifted into small soft slabs that were easy to trigger. Photo: GNFAC

This pit was dug in Hyalite Canyon near Twin Falls. It showed 2 mm facets (sugar snow) underlying the snowpack. This layer did not break in stability tests, but anticipate these grains will get weaker with time. Photo: GNFAC

For the Bozeman Ice Fest we investigated the Silken Falls and Avalanche Gulch gulleys. They were wind-loaded and had weak snow mid-pack that was unreactive. Avalanches in these gulleys would be deadly, so be extra vigilant in your assessment before crossing. Photo: GNFAC

For the Bozeman Ice Fest we investigated the Silken Falls and Avalanche Gulch gulleys. They were wind-loaded and had weak snow mid-pack that was unreactive. Avalanches in these gulleys would be deadly, so be extra vigilant in your assessment before crossing. Photo: GNFAC

We found 80 cm (2+ feet) of snow on a NE facing slope at 8,000 feet outside Bridger Bowl's Boundaries. The snow was supportable with a weak layer at the blue card. Faceted, weak, sugary snow is the layer of concern, but it was not that bad...yet. We'll be watching to see if it gets weaker. Photo: GNFAC

Monday night's new snow formed wind slabs from the strong wind on Tuesday. We are finding these throughout southwest Montana. Photo: D. Britt

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

This post and picture was on the FB ice climbers page. This is from Comet Alley, a steep gully off the East Fork Road:

Today we found that this gully has some significant loading. We triggered a few wind slab slides on the approach. We managed to get a quick lap on the route and got out before it got loaded more. TBH with more unconsolidated snow I’d reconsider going there.

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 in Hyalite Canyon observed a small wind slab avalanche just below the ridgeline in Divide Cirque (below cornice on the peak in the center of the photo). Photo: T. Saulnier

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

This powder cloud from a large avalanche was seen on Black Mountain, up Pine Creek outside Livingston. Located outside our advisory area it is a sign of unstable snow, likely from wind-loading, that can be found throughout southwest Montana. Photo: Anon

Skiers found a shallow snowpack and very windy conditions today. Snow was moving and loading slopes. Photo: H. Darby

From an obsevation: Skied up towards Arrowhead Bowl from Fairy Lake road. Snowpack is still very thin in the trees as you ascend towards the ridge. Strong westerly winds and exposed rocks deterred us from skiing the bowl itself. Down low we found variable conditions ranging from a few cm of graupel to a few cm of windboard and ice in places. We dug a pit at 8140 feet, 143º SE. The snowpack is 55 cm deep with a very distinct knife hard crust layer from 0-20cm above the ground, we were thinking that could be due to a rain on snow event that fell on top of the October snow. There is also a distinct knife crust 40 cm above the ground with new snow/wind blown snow on top of that. Weather today was mostly clear with a few scattered clouds and consistent winds, with very strong gusts from the west. Photo: H. Darby

A natural avalanche on Saddle Peak on 11/10/21. Strong winds drifted recent snow into thick slabs near the ridge. This slide was probably one of those wind slabs breaking and/or being triggered by a cornice fall. Photo: P. Hinz

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

From e-mail 11/4/21: "Hiking up in the Bridger Range from Sacagawea Pass and noticed no faceting of the current snowpack. The snow near the pass and on the ridge is very wind affected as is to be expected and dropping into the bowl on the east side of the Pass the snowpack there has a distinct sun crust. Dug around a little bit at 8600 ft on a NE aspect and found a sun crust of about two inches with what felt like rounded grains below that. Even in the direct sun, the crust was taking a long time to rewarm and was pretty slippery..." Photo: H. Darby