Avalanche Forecast

Issued: Nov 29th, 2014 8:28AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is low. Known problems include Storm Slabs.

Avalanche Canada rbuhler, Avalanche Canada

A Special Avalanche Warning has been issued for this weekend. Now is an important time to exercise restraint and stick to low angle terrain.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

An Arctic high pressure system dominates the forecast for the next few days. Clear, cold, and dry conditions are expected until at least Thursday.Sunday: Sunny, treeline temperature around -20, light NW alpine wind Monday: A mix of sun and cloud, treeline temperature around -18, moderate SW alpine wind Tuesday: Mostly sunny, treeline temperature around -15, moderate-strong NW alpine wind

Avalanche Summary

We finally received some information from the Golden area. Shout out to Matt and Aaron, thanks guys! Widespread natural activity size 2-3 was reported on Friday around Golden. Remote triggering from up to 50m away was also reported. Slabs were up to 1m deep and avalanches were running full path.Widespread natural activity up to size 2 on all aspects above 1800m was reported on Thursday and early Friday in the Invermere area. Explosives and ski cuts produced further results on Friday but triggering appears to have become more difficult after the temperatures plummeted and refroze the wet snow surface.

Snowpack Summary

The storm produced slabs up to 1m thick in the north of the region and around 40-60cm thick in the south. This slab sits on the mid-November weak layer (surface hoar, facets, and/or a crust). Below this you will likely find a 15-20cm thick layer of sugary facets, which is sitting on a solid rain crust from early November. Reports of whumphing and remote triggering on these layers suggests a persistent weakness with the potential for large propagation. Recent strong and variable winds have likely created dense wind slabs in exposed terrain and resulted in variable snow distribution in the alpine. On Thursday, high elevation rain produced a new crust. In the Golden area this rain crust exists up to around 1600m whereas in the south it is up to 2000m or higher. As temperatures dropped, 10-20cm of new snow fell on top of this new crust.

Problems

Storm Slabs

An icon showing Storm Slabs
A slab 50-100cm thick sits on a touchy weak layer and is producing large avalanches. Strong alpine winds have loaded leeward features in exposed terrain creating touchy wind slabs.
Be alert to conditions that change with elevation.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Nov 30th, 2014 2:00PM