Front Range
AvalancheRyan Lewthwaite · Mar 2, 2020 · Front Range
Weather
Sunny skies became overcast and a snow rate of S2 was observed. The winds at ridgeline were moderate gusting strong with banners of snow. Air temperature of 20F.
Snowpack
4 to 6 inches of new snow fell overnight. The moderate to strong northwest winds were transporting the new snow to lee aspects and features. The deposits of drifted snow were denser than the snow underneath, especially in exposed areas near treeline. Cracking, collapsing, and hollow sounds were observed in the drifted snow. Convex steep roll-overs and concave gullies showed these signs of unstable snow. Northeast aspects near treeline have over 60cm of depth hoar at the base of the snowpack. With hard forces the weak basal layers can collapse, and is a catalyst for the large step-down avalanches we have seen. Propagations are stubborn to initiate but are not out of the question.
Avalanche
I observed the remnants of a large slab avalanche across the Herman Gulch valley. The crown was barely visible along a southeast ridgeline above treeline. The debris was nearly 3/4 of the way down the runout with large intact chunks. It appears to be a cornice fall avalanche that stepped down into deeper weak layers of the snowpack.