Avalanche Forecast

Moderate - Intensity of incoming weather systems is uncertain

TUESDAY: Snow. Accumulation 15-25 cm. Ridge wind strong to extreme, southwest. Temperature -10. Freezing level valley bottom.WEDNESDAY: Mostly cloudy, light flurries. Accumulation trace. Ridge wind light to moderate, west. Temperature -12. Freezing level valley bottom.THURSDAY: Mix of sun and cloud. Ridge wind light, south. Temperature -10. Freezing level valley bottom.

Sunday a remotely-triggered (from a distance) size 1.5, slab avalanche was observed on a southerly aspect at 1700 m. A weak layer buried in early January was the suspected failure plane. A very large, widespread avalanche cycle up to size 4 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.

Strong north to north-westerly winds have loaded lee slopes with 30-40 cm recent storm snow. Alpine and open treeline areas have seen extensive wind-affect from strong, northerly winds, while a sun-crust has formed on solar aspects. Below the snow surface, 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 at least one of these layers 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.