Northern Gallatin

We toured into Beehive and Bear Basins on the final day of the Arctic deep freeze. No forth coming signs of widespread instability, but we found unstable results in our snowpit on the SW facing slope to the south of Tyler's (ECTP18). The slab failed and propagated on depth hoar near the bottom of the snowpack. North of Spanky's in Bear Basin, there was plenty of weak snow but insufficient slab to propagate failure in tests (ECTX and PST 30/100 Slab Fracture). 

The weak snow making up the foundation is nearly universal, but the snowpack is not universally unstable. Where these weak layers are capped by a sufficient slab of cohesive snow from wind-loaded drifts or recent storms, they can produce avalanches. Avoid the avalanches by seeking out lower-angle terrain or minimize the odds of triggering a slide by selecting terrain sheltered from recent wind loading and testing for instability before considering steeper terrain.

Got some cardio in this morning due to lack of snow and a partner. Skinned to palisade falls and the cross country trail on the north side of sleeping giant. Went off trail a few times and instantly felt unstable. Falling through 2-3 different layers of snow. I also observed a few shooting cracks. Went off the side of the road on the inbankment and couldn’t even get up due to sugary snow just collapsing underneath me. A layer could be seen under the snow about 3-5 inches of the fresh snow and old snow. And another around the 6 inch deep mark. 

Skied the S/SE face of Blackmore this morning. Had several large collapses lower in the basin, as well as the ridge. As NOAA predicted, winds started cranking at 10:30am which was time to go, most of the tracks in the area were covered up within an hour.  

From Obs:  "While skiing one of our intended slopes, one of my partners skied over a small rollover and as he arrived at the bottom of the small slope a pocket had released above him and stopped just above where he was standing. The culprit was again the recent snow on top of older faceted snow." Photo: Anonymous 

Traveled into the Blackmore area to find some soft snow and compiled a number of observations. We performed a quick ECT on a NE facing slope at roughly 9000’ in a slightly wind loaded terrain feature and got a result of ECTX. In our pit we did identify the potential for a 3-5” slab consisting of the recent snow to avalanche in certain situations. We felt this was a manageable hazard as long as it was not on a large slope with exposure. While touring we also noticed a small avalanche (presumably natural) on the E face of Blackmore. It is in the attached photo. Later we dropped a refrigerator size cornice onto a steep slope and got a small pocket of the new snow slab to release confirming our earlier suspicion. While skiing one of our intended slopes, one of my partners skied over a small rollover and as he arrived at the bottom of the small slope a pocket had released above him and stopped just above where he was standing. The culprit was again the recent snow on top of older faceted snow. 
 

Overall was a successful outing and we scored some good snow while managing the hazard we had identified. 

Wind loaded gully above Crypt Orchid in Hyalite. Photo: T Hughes