Multiple large natural and explosive controlled avalanches have occurred since Wednesday and some have ran into below treeline terrain. Continued moderate to strong winds with light flurries will keep the hazard elevated for Saturday. Cautious route finding and conservative decision-making are essential for this weekend.
Strong to extreme SE-W winds have created wind slabs on all aspects in the alpine and in open terrain at treeline. Winds are forecast to continue for Saturday and will add to the slab formation. These slabs will remain reactive for the next few days.
More snow from wind transport and light flurries will add mass to the slab sitting on top of the mid-pack Nov 22 facet/crust layer and the deeper Nov 13 facet/crust layer. While the likelihood will slowly decrease, we still expect large avalanches on these layers for the next couple of days.
On December 19th avalanche control was conducted on Mt Stephen, Field, Bosworth, and Cathedral that achieved results up to size 3, but generally to size 2.5, some of the terrain had been previously controlled. Ski hills reported some explosive results, and a skier remote up to size 2 involving the persistent or wind slabs.
Avalanche control on December 18th on Mt Dennis and on the Sunshine access road produced similar results to size 3 where avalanches ran to 3/4 runout.
With the continued wind and snow over the past week, there is now a 50 -100 cm+ slab overlying the November crust / facet layers. These layers have been active this week with avalanches up to size 3.5, occasionally scrubbing to ground.
Below 2100m, a new crust has formed below the recent snow as the temperatures cool from the weekend warmup.
Treeline snowpack depths range from 100-180 cm!!
Light flurries Friday night (2-10 cm) and flurries through Saturday (10 cm). Moderate west winds overnight, increasing to strong SW winds on Saturday. Treeline temperatures will be around -12C overnight and Saturday. Another system is forecast for Sunday-Monday, but snow amounts are uncertain at this time.
Link to updated weather forecast tables from Environment Canada.
