The biggest storms of the season are upon us along with touchy avalanche conditions. Now is a good time to stay out of avalanche terrain and enjoy the new snow in simple terrain or at your local ski hill!
5-10 cm of new snow is forecasted on Wednesday. This will add to the recent storm snow and will sluff easily in steep terrain at all elevations.
30-60 cm of recent snow has created touchy slabs and more snow is on the way. These slabs overlie the Feb. 3rd crust/facet combination and are primed for triggering. Numerous natural & skiier triggered avalanches have occurred in the last 2 days on this interface, some have stepped to ground.
Some of the recent avalanches are stepping down to the basal layers near the ground. This seems to be most common in thin, steep, rocky and higher elevation locations and less of a concern in thicker snowpacks with a dense mid-pack. Recent loading has made this layer more sensitive.
Forecasters have observed continued evidence of a widespread avalanche cycle following the recent storm.
Avalanche control on Mt Whymper (Kootenay NP) on Tuesday produced size 2-3 avalanches with every shot. The crowns were 40-100 cm deep and the failure planes were the recent storm snow sliding on the Feb. 3rd crust and occasionally stepping down to ground.
30-60 cm of recent snow sits on top of the Feb 3rd crust/ facet layer. This crust is variable in thickness and exists up to 2500m (higher on solar aspects). In thinner eastern areas, the mid and lower snowpack are weak and facetted.
Average snowpack depths at treeline range from 80 cm in thinner eastern areas to 150 cm in thicker western areas.
A low pressure system is arriving overnight Tuesday that will bring 30-50 cm of snow warmer temperatures and strong SW winds.
Wednesday: 5-10 cm, strong SW winds, ~ 1800m freezing levels
Thursday: 15-30 cm, strong SW winds decreasing to moderate in the afternoon. Freezing levels dropping to valley bottom
Friday: System clears, potential for upslope snow.
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