Avalanche Forecast

Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.

MONDAY NIGHT: Partly cloudy, 40 km/h wind from the northwest, alpine temperatures drop to -12 C.

TUESDAY: Mix of sun and cloud, 30-50 km/h wind from the west, alpine high temperatures around -6 C.

WEDNESDAY: Mix of sun and cloud, 30-50 km/h wind from the west, alpine high temperatures around -6 C.

THURSDAY: Scattered flurries with up to 5 cm of new snow, 40-80 km/h wind from the west, alpine high temperatures around -4 C.

Several notable large persistent slab avalanches (size 2-3) have been reported in alpine and treeline terrain over the past few days. Most of them were triggered with explosives, but one was remotely triggered as a person walked on low angle terrain above the slope. These avalanches have run on buried crusts and weak layers ranging from 50-100 cm deep. This type of activity is indicative of a weak snowpack structure capable of producing large avalanches.

In addition to these large avalanches, smaller storm slab and wind slab avalanches were triggered by humans over the weekend, and may still be possible to trigger in steep and wind affected terrain. A concern with triggering one of these smaller avalanches is the potential for it to step down and produce a larger avalanche on the deeper weak layers. 

20-30 cm of recent snow has been redistributed by the wind to form wind slabs in the alpine and near treeline ridgetops. Crust layers from November and October can be found 40-100 cm deep in the snowpack (check out this MIN report from Mear Lake). These persistent weak layers have recently produced some large avalanches. We are uncertain about the spatial distribution of these layers, but suspect they are widespread at upper elevations where early season snow existed. We are also uncertain about how reactive these layers could be to human triggering. Overall, a conservative approach to travel in avalanche terrain is recommended with this concerning snowpack structure. Snowpack depths range between 50-100 cm at higher elevations and taper rapidly below treeline.