Avalanche Forecast

Issued: Feb 21st, 2018 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Persistent Slabs and Wind Slabs.

deryl kelly, Parks Canada

Jasper.

Despite the Moderate rating, back-country users should continue to travel conservatively at treeline as a stiff, persistent slab sitting over weak layers will continue to plague the back-country, for the foreseeable future.

Summary

Weather Forecast

Cold air from the North is insistent on staying in the Park, for now! As the weekend approaches we can expect gradual warming, light snow flurries, and gusting winds from the SW at higher elevations.

Snowpack Summary

15cm snow over the last week, and available snow from the previous storms, has been redistributed by strong winds from variable directions to build slabs and wind effect in open areas. A persistent slab sitting on three weak layers down 50 to 80cm can be found throughout the forecast region and has produced many large avalanches traveling full path

Avalanche Summary

Older windslab to sz 2 observed from a typically cross-loaded alpine features in the Icefields region, SE aspect, 2500m. An extensive cycle was seen recently, as the persistent slab became overloaded with successive storms. Avalanches to sz 3.5 were observed from most aspects and most elevations with the majority of the action seen around 21-2500m

Confidence

Problems

Persistent Slabs

A stiff slab 50 to 90cm thick, sits over sun crusts on south and west aspects, Surface Hoar preserved at, and just above treeline and weak faceted crystals lurking in shallow snowpack features. This is a dangerous problem that is difficult to avoid.

Use conservative route selection, stick to supported terrain features, avoid overhead hazards.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3.5

Wind Slabs

While the winds have abated, they blew hard, and from a variety of directions last week. Windslabs are hard in the alpine and they exist well into treeline areas. These can be expected to be be sensitive to skier triggering.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.The best powder will be found in sheltered locations at or below treeline.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Valid until: Feb 22nd, 2018 4:00PM