Steamboat & Flat Tops

Avalanche

CMC AIARE Lvl 1 · Jan 23, 2021 · Steamboat & Flat Tops

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Weather

Blowy and snowy in the 8500-9000ft range. 10-12" of new snow overnight with another 3" falling during the day. Winds were light with moderate to strong gusts out of the WSW during the height of the storm. Snow transport was moderate to intense during this time as well and was building some stiffer wind slabs during our tour, some of which failed naturally on 40 degree slopes. Most intense snowfall rates were probably in the 3-4cm/hr rate. Storm began to lift and exit the zone around 2:00pm and winds and precip slowed down as well. Temps in the mid-20's most of the day.

Snowpack

Toured thru east and SE facing terrain, 8500-9000ft. ~100cm snow depth, with 30-45cm storm snow in some areas. SE faces had 2-3cm sun crusts with facets above and below and we got some medium to hard CT results on this layer, no surprise as the persistent slab has been active in most pits this year. We did find the storm slab was cracking in and around the skin track and in some cases was fairly reactive in snow pits (2 CTE results and two CTM results on the storm slab layer). We also had a few localized whumphs during the tour. Test slopes showed movement in the storm slab under the weight of a single skier.

Avalanche

Two small (D1) natural slabs released on ~40 degree E & NE aspects below treeline during the day and crown lines quickly filled back in with new snow. Three to four more loose, dry slides seen in very steep creek banks & road cuts.