Northern Gallatin

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

Is this evidence of an early slide / run out zone from the early snow (to left / East of photo) ?

This morning I toured up Mt Blackmore to check out the new snow. I tested the snowpack on a SE aspect of the east face of Blackmore at approximately 2905m in elevation. At this location, the new snow total was around 10cm. An ECT resulted in ECT16N @ 20cm. This failure occurred at an interface below a rain/ice crust that had pencil hardness and about 7cm thickness (photos). A shear test conducted on the remaining ECT column (photo), and a handful of hand shears on the approach, resulted in Q1 shears with medium to difficult effort. The new snow was well bonded to this crust and I observed no failures or movement at this interface. I observed small and isolated collapsing on the skin track during the approach (photo). Gaining the east ridge, I observed wind loading and a wet loose release on the east face (photo). With additional snow and sun in the forecast tomorrow, I am concerned with the potential for the below crust interface to propagate.

From obs: 5/9/21: "Yesterday we went to check out the new snow in Beehive Basin... Looking down into the face of Peruvian, we observed a natural dry loose slide that released from the ridge... We observed an increase in wind speed throughout the morning, and a shift in wind direction from west to southwest in the early morning moving to west to north west by the late morning. The combination of variable and high winds with the amount of new snow available for transport created a noticeable increase in the hazard of wind slabs on all aspects we observed during the morning..." Photo: E.

From obs: 5/9/21: "Yesterday... While traversing... along the north ridge of 10602 [in Beehive], we triggered a small wind slab  that carried down into Peruvian, which then released another small wind slab on a northeast aspect of the face (photo). The crown height of this wind slab was measured at 60cm at it's deepest point, and approximately 30ft wide by 10ft long. Looking down into the face of Peruvian, we observed a natural dry loose slide that released from the ridge.

Small wet loose slide that a skier triggered, running over an older crown from prior days. East aspect, 10,000'. From 5/7/21. Photo: D. Britt

Photo of a large natural wet avalanche in Taylor Fork, NNW aspect around 9,000' elevation near Koch Peak, on 5/3/21. Photo: D. Britt