Avalanche Forecast

Moderate - Intensity of incoming weather systems is uncertain on Tuesday

MONDAY: Mainly sunny, with increasing clouds late in the day. Light winds. Treeline temperature near -10.TUESDAY: 20-30 cm snow. Moderate westerly winds. Treeline temperature near -5.WEDNESDAY: Flurries. Light winds. Treeline temperature near -8.More details can be found in the Mountain Weather Forecast.

A very large, widespread avalanche cycle was observed on Thursday and Friday. Slopes of all aspects and elevations ran full path and reached valley floor. In some cases, mature timber was destroyed. Many of these failed on persistent weak layers, while some involved only the recent storm snow. The natural cycle has wound down, but human-triggering remains a real concern. Avalanches are most likely to be triggered with a large load, (like a snowmobile landing a jump, a cornice fall, or a solar-triggered avalanche stepping down), or from a thin-spot trigger point, like around trees or rocks. You might be surprised by how large an avalanche can be triggered and how far it could run.

Strong north to north-westerly winds have loaded lee slopes with 30-40 cm recent storm snow. This adds to an existing storm slab up to 1m deep from the last couple of weeks' accumulation. Several persistent weak layers make up a troublesome snowpack. In the top 1-1.5 m of the snowpack, two surface hoar layers buried in January can be found. Expect to find one or other of these on all aspects and elevations.Deeper in the snowpack (120-200 cm deep) is a facet/crust/surface hoar layer from December, most prevalent at and below treeline.Near the base of the snowpack is a crust/facet combo, most likely to be triggered from thin spots in the alpine.All of these layers have produced large avalanches recently. The wide distribution and ongoing reactivity of these layers suggests that avoidance through choosing simple terrain is the best strategy.