Human triggered avalanches are likely at the upper elevations today, especially in areas where wind affected snow overlies buried weak layers and crusts. These buried weak layers are located 1-3 feet down from the surface of the snow and DEEPER. Pay attention to signs of instability such as cracking within wind drifted snow and audible collapsing of the snowpack.
Wind slabs: Soft wind slabs that are 1-2 feet thick will be sensitive to human triggering at the middle and upper elevations. Winds averaged out of the SSW and will veer to the W today.
The failure plane for all new snow problems will likely be the most recent crust that was buried on 3/30.
The March 20th interface is now buried 1-3 feet below above a stout slab. Active loading of new snow with heavy wind transport will add stress and increase the chance of triggering a large avalanche. This layer is composed of facets/crusts on solar aspects and small preserved facets on northerly aspects protected by the sun. The sensitivity and distribution of this layer is hard to gauge due to the varying slab depths, recent temperature fluctuations, and differing characteristics across slope aspects. Remote triggering could occur from gentler slopes above, below, or adjacent to steep slopes. Wind loaded terrain will have the highest likelihood of finding reactivity. Long story short: persistent slab avalanches are unpredictable, so conservative decision making and careful snowpack evaluation are required.
Deeper weak layers formed earlier in the season composed of crusts, facets, and depth hoar remain a concern. Triggering a wind slab or persistent slab on the March 20th interface could step down to these layers resulting in a large to very large avalanche.
(3/27/2023)
Avalanche triggered from a low-angle ridgeline in adjoining steep terrain on a NE aspect around 10,000'.
Photo: Antonioli
Togwotee has picked up 6-8 inches of snow over the last 24 hours with winds on Grouse averaging 18 mph out of the SW. Current temperatures are in the teens on the peaks. The forecast for today is for more snow and breezy, with an additional 2-4 inches of accumulation possible.
Recent avalanches
