Avalanche Forecast

Moderate - Intensity of incoming weather systems is uncertain on Tuesday

Tuesday Night: 10-15cm of new snow / Strong southwest winds / Alpine temperature of -9Wednesday: Generally overcast skies / Moderate northwest winds / Alpine temperature of -13Thursday: Mix of sun and cloud with scattered flurries / Light and variable winds / Alpine temperature of -17Friday: Overcast skies / Moderate northwest winds / Alpine temperature of -10

On 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 last 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 mentioned in the snowpack discussion.Looking forward, expect a new round of storm slab activity in response to new snow and wind on Tuesday night. Storm loading has the potential to re-activate deeper, more destructive persistent weak layers.

By Wednesday morning I would expect up to 30cm of new snow. Forecast strong ridgetop winds are expected to redistribute the new snow into much deeper, reactive slabs in wind-exposed terrain.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.