Steamboat & Flat Tops

Avalanche

Jason Konigsberg · Jan 27, 2023 · Steamboat & Flat Tops

Weather

New snow in the last 24 hours was 35 cm (14 inches). It snowed another 2 inches during the day. Snow was picking up again in the late afternoon.

Snowpack

The storm snow was reactive with lots of shooting cracks 10 to 20 feet in length and a depth of about 8 inches. The weak layer was very low density snow. Temperatures rose throughout the storm from when snow started falling on Thursday night. The storm snow was more reactive where it was slightly stiffened from the wind and then more reactive directly below ridgetop where loading was occurring. Besides the storm snow instability, wind slabs were forming near ridges, and sluffing could be initiated especially on due south-facing slopes. Below the storm snow is 8 inches of snow that fell on Tuesday night which is now four-finger hard. Below this is a melt-freeze crust on east to southerly-facing slopes. In extended column tests, I got propagating results on isolation on the above-mentioned density change. I also got a moderate propagating result below the crust on a southeast-facing slopes. There weren't any signs that avalanches are breaking more deeply and on this crust/facet combo right now, but as snow continues it is something to watch. More so where wind-loading is greatest.

Avalanche

I triggered one small avalanche on a slightly wind-drifted easterly-facing slopes. The slab was only about 8 inches thick and it wasn't very wide. Avalanches will likely grow in size and get wider as the slab settles a little and becomes more cohesive.