Avalanche Forecast

Issued: Nov 28th, 2014 8:22AM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is moderate. 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 weather pattern for the weekend. Cold and dry is the theme for the next few days.Saturday: Sunny, treeline temperature around -20, light-moderate NE alpine windsSunday: Sunny, treeline temperature around -25, light NW alpine windsMonday: A mix of sun and cloud, treeline temperature around -20, light W alpine winds

Avalanche Summary

We haven't had any new reports since last weekend. If you have any observations, please send them to forecaster@avalanche.ca. Recent observations from the Rogers Pass area where the conditions are expected to be similar include widespread natural activity up to size 3.5 on Thursday.

Snowpack Summary

The storm produced a slab up to 1 m thick which sits on the mid-November weak layer (facets, surface hoar, and/or a sun crust on steep southerly slopes). 20-30cm below this layer is a thick rain crust with weak facets on top. Snowpack data from the Cariboo region is very limited at the moment but I expect these layers are reacting similarly to the North Selkirk/Monashees because the formation conditions were generally the same. In the Rogers Pass area, the storm slab is poorly bonded to the mid-November layer and snowpack tests suggest it can be triggered easily with wide propagations possible. In some snowpack tests, the deeper crust/facet layer was also failing and it is possible that avalanches may step down to this lower layer.Recent strong and variable winds have probably created dense wind slabs in exposed terrain and resulted in variable snow distribution in the alpine. At lower elevations, expect travel to be difficult and potentially hazardous as many early season hazards are exposed or lightly buried (stumps, logs, rocks, open creeks, etc).

Problems

Storm Slabs

An icon showing Storm Slabs
A slab up to 1m 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

Likely

Expected Size

3 - 5

Valid until: Nov 29th, 2014 2:00PM