Steamboat & Flat Tops
AvalancheRon Simenhois Jason Konigsberg · Mar 26, 2021 · Steamboat & Flat Tops
Weather
For most of the day, the weather was calm, with partly cloudy skies and dark skies to our north. At about 1 PM, the visibility became limited at above 11500 ft, and snow in the form of graupel started. We estimated the total snowfall throughout the day 1 to 2”.
Snowpack
The snowpack depth and strength changed dramatically with elevation and aspect. The snowpack below 10000 feet was less than 1 meter thick with a supportable crust on both north and south aspects. No avalanche hazard at these low elevations right now. Above 10000 feet and up to NTL, the snow depth is 120 to well over 2m on NW-N aspects. In a snowpit on a below treeline northwest aspect, we found a well-preserved faceted layer that propagated a fracture in an ECT test at about 1 m below the surface (see attached snowpit). In a deeper pit on a near treeline north aspect, we found a stable and deep snowpack. We tested the upper layers in the top 80 cm and found the upper snowpack unreactive to tests. The snowpack was well above 2 meters thick. In places, it was hard to probe to the ground through thick, hard layers on northeast and east aspects near and above treeline. Overall we encountered a stable snowpack with no signs of instability. There are a few worrisome areas like northwest slopes especially below treeline. We talked about avoiding open areas with protruding rocks on these slopes. There are also some northerly slopes with very uneven snow coverage where you may be able to trigger a large avalanche from a thin and rocky spot. Constant probing and evaluation of the snowpack is necessary to make sure the snow coverage is deep and consistent before committing to steep slopes.---The dust layer was 27 cm down from the snow surface below treeline and 45 cm down near treeline. This is a good marker for the amount of settled snow since March 10.
Avalanche
None observed. A large crown is still visible from mid-February below the summit of Parkview