24-25

Plenty of wind slabs ranging in size on Lionhead ridge and on surrounding slopes. Photo: Riley

Some recent avalanche activity noted on east Mt. Henderson. Photo: B Fredlund

Some recent avalanche activity noted on Miller Ridge. Photo: B Fredlund

Saw a number of slides today, as to be expected. All the large ones I noticed were north facing. Also, the dirty snow was so odd to see mid winter. It was brown all over the sled zone.


 N face of crown butte, looks like it slid before the dirt event (we think the end of the storm yesterday/ or last night must have been dirty snow?). It was extremely deep and terrible vis yesterday, but blower snow. Not the case today with how warm it got.


This is the N side of scotch bonnet, looks like a big break, didn’t get any closer than this however.

Also saw some decent sized slides on the N side of Henderson, but was too far away to get photos.


Just a little wind load cornice break, but it broke while I was coming down that track to the right.

Skier triggered wind slab avalanche on Saddle Peak. Photo: BBSP

While sledding today we observed 3 different avalanches. The first was on E Henderson above the bench in nearly the same spot as the 12/30 avalanche. It ran sometime between 11:30 and 12:30 today. 

The second was on the north aspect of Scotch Bonnet. The third was on the north aspect of Crown Butte. We don't think these broke on any deep PWLs, since none of the crowns were impressively deep. The latter two likely ran at the end of the storm yesterday. The crowns were starting to drift in, but there was little to no new snow on the debris. 

Notably, there is a widespread dust layer on the snow surface, and possibly another layer further down within the recent storm snow. 

Blowing snow was moderate to intense at ridgetops and west aspects are scoured. Winds were light to moderate out of the S and W. Skies were SCT to BKN.

This slab from my ski cut was about 20” deep and 60’ wide. It’s NE facing so pretty wind blown. Photo: S Budac

Shooting cracks on Tick ridge in the Dudley drainage. This slab from my ski cut was about 20” deep and 60’ wide. It’s NE facing so pretty wind blown. I took a gladed path but in more open sections I imagine this would have propagated much wider and further downslope. Probably 35 degrees here.

Today, we had the pleasure of riding with USFS Snow Rangers from Bozeman, Livingston, Gardiner and Cooke City. We rode into First and Second Yellow Mule and Buck Creek drainages. 

Temperatures were warm, topping nearly 40 degrees at the parking lot around 4pm. Strong winds blew all day from the SW, sustaining 30mph at ridgelines. Snow was actively transported all day by winds, and plumes were visible on far away ridgelines and summits. There was around 1.5-2' of new snow from the weekend. Widespread dirt and/or dust was also noted on snow surfaces.

Our primary concern today was slopes where strong winds had formed thicker slabs from recent snowfall. On the headwall of the Second Yellow Mule, we saw two recent wind slab avalanches. These were small (R1 D1), immediately below the ridge, and likely broke late last night or this morning. 

Our snowpits today were relatively anticlimactic. We were curious as to how recently buried weak layers were reacting to the new snow. In three separate locations, we performed multiple tests and saw high scoring propagation in only 2 of 9 total tests. This propagation was difficult to replicate. We had ECTN's within the new snow and on the new/old interface. We found broken surface hoar feathers and facets under the new snow, but even those weak grains were not visible in every pit. That being said, we did not travel into Bear Basin, where, prior to the recent snow, Alex found large, buried surface hoar  (https://www.mtavalanche.com/node/33832). We did not observe any cracking or collapsing.