Northern Gallatin

Toured in divide cirque today. There was about 24” of fresh snow which made trail breaking very difficult. I did a quick pit and found a fist hard slab sandwiched between two layers of very low density snow. My guess is this layer formed when the cold front passed last night. I stuck to low angle terrain. In the basin, between pt 10,201 and 10,024 there was a very large avalanche that must have slid yesterday or last night. It looks like it propagated at least 1000’ wide and at the deepest the crown was easily 5 feet. Visibility was low so it was hard to tell, but it was definitely a big slide. Light snow in the AM became moderate in the afternoon, and it began accumulating rapidly.

Skied off the shoulder of Blackmore today. No recent avalanche activity was evident, not even sloughs down the face. New snow was right side up and well bonded. Was still seeing propagation in pits in the low to mid 20s range though. Generally breaking on a layer of faceted snow sitting below a melt freeze crust about 2ft down.

NW aspect 6200’
37 degree slope
11:48am
27f
41cm snow pack
ECT6P
Full propagation on depth hoar layer 26cm deep.

PST 40/100 END

SW aspect at 6800’
Air temp -1c
CT16NP
ECT21NP
PST6
23” snowpack
The same two layers, wind/sun or rain crust with a surface hoar layer and 8-10” of depth hoar/facets at this location. We did not see cracking, collapsing or whoomphing. Traveled up the ridge of the south aspect of the sunshine mine drainage.
Approximately at 45 31’58”N 11101’45”W

There were many loose snow avalanches or sluffs with the 8" of new snow in Hyalite. These avalanches were not breaking as slabs but a thin layer of weak, near-surface facets caused the new snow to slide actively. Photo: N. Salsburg

There were many loose snow avalanches or sluffs with the 8" of new snow in Hyalite. These avalanches were not breaking as slabs but a thin layer of weak, near surface facets caused the new snow to slide actively. Photo: S. Reinsel

Toured in divide basin today. I dug a pit at 9400’ on a NE aspect (HS130) to look for weak layers and found 3. There is a layer of near surface facets at 110 cm, buried surface hoar at 92 and depth hoar 61 to the ground. Between 90 and 62 there is a 1 finger slab. The depth hoar is very weak. I did an extended column test and it did not propogate, but I was not planning on skiing slopes steeper than 30 degrees anyways. High clouds in the AM gave way to bluebird skies in the afternoon. Around 1:30 the temperature began to rise and I left before the snow got sticky. A SW wind was moving snow along hyalite ridge, where there were numerous small loose dry avalanches. Winds were fairly calm in the basin but there evidence of wind transport.

From obs: "A natural avalanche occurred on an East aspect in the Maid of the Mist basin. It appeared to have slid last night/this morning. Visibility made it difficult to determine the extent of the debris or the depth of the crown." Photo: S. Wilson