Avalanche Forecast

Issued: Feb 19th, 2014 4:00PM

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

garth lemke, Parks Canada

Jasper.

Buried surface hoar, facet, crust combo about 30cm down is the main concern found at treeline and subalpine locations particularly on NE aspects. This layer will persist.

Summary

Weather Forecast

Expect 5cm of snow Wednesday evening into Thursday. Flurries will continue until Saturday with sun and cold overnight temperatures after that. Temperatures trending colder next few days with light westerly winds.

Snowpack Summary

10cm overnight adds to the previous storm's 20cm snow overlying a surface hoar, surface facet and crust combo roughly 30cm down (Feb 10 layer), found predominantly at tree line and sub alpine elevations A hard mid-pack is providing bridging strength over the weak basal facet layer. Below tree line has a supportive yet shallow mid-pack.

Avalanche Summary

Patrols occurred in Maligne and Icefields Wednesday. Nothing noted in the Icefields. Skiers triggered a size 2 at Maligne area, 35m wide, 60m long, on a NE aspect 38 degree slope just above treeline on the Feb 10 surface hoar/facet layer. Stability tests showed moderate sudden planar/sudden collapse on this layer.

Confidence

Problems

Persistent Slabs

The persistent slab interface is a combination of crusts, facets, and surface hoar overlying a solid midpack bridging weak basal facets. It will be large if triggered. Caution on steep lee treeline and subalpine aspects with variable snow depths.

Assess start zones carefully and use safe travel techniques.Caution around convexities or areas with a thin or variable snowpack.

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

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Wind Slabs

Caution on East aspects above treeline especially at ridgecrest transitions. Field patrol in Maligne area triggered size 2 of this nature where wind has firmed the recent storm snow into a windslab overlying previous layer of facets and surface hoar.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Feb 20th, 2014 4:00PM