Steamboat & Flat Tops
AvalancheJason Konigsberg, Austin Divesta · Mar 24, 2025 · Steamboat & Flat Tops
Weather
Warm and sunny. It was breezy and cool in the wind through open parks and near ridgetop.
Snowpack
At higher elevations (~11,300 ft) at the top of the below treeline elevation band, the snowpack was 2 meters deep on northerly-facing slopes. We didn't dig to the ground, but this fits the pattern in other Northern Mountains areas where basal weak layers are hard to affect. On east through south-facing slopes at this elevation, the snowpack was 140 to 160 cm deep with much deeper drifted spots. We dug on an east-facing drifted slope and found a 70 cm thick cohesive slab resting over a thin layer of facets on top of a thick impenetrable melt-freeze crust (from the late Feb/early March warm-up). We got east propagating results in an ECT on the facets below the slab. In general, at the upper end of the below treeline elevation band, upper snowpack weak layers are more concerning than basal layers. These upper snowpack layers could also be a problem for future wet slab conditions to develop, especially if freezing levels are above 11k ft at night. At lower elevations, the snowpack is thinner and weaker. We dug on a north-facing slope at 10,700 feet and found a snowpack that was 150 cm deep with weak basal layers. There was an especially weak layer below a rain crust in the bottom portion of the snowpack. Again, this is shallower than normal for the Flat Tops, but I have dug at a similar elevation in other parts of the N Mts and found a similarly weak snowpack at 10,700 feet on north-facing slopes. This structure is concerning for a large storm or high freezing levels and wet slabs with a big warm up. Southerly slopes below treeline are generally well consolidated with many ice bodies and melt-freeze crusts throughout the snowpack. There is 15 cm of recent snow that was starting to get wet. This will generally be a loose wet problem until all of the new snow transitions to melt forms. These southerly below treeline slopes don't seem to have the structure for wet slab avalanches.
Avalanche
We saw a couple of small wind slab avalanches. One was near White Owl Lake and one was above the cliffs of Blair Mountain. We observed a lot of steeper east and southeast terrain in the ravines of the Flat Tops and only saw rollerballs, no wet avalanches.