Avalanche Forecast

Issued: Mar 2nd, 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.

Garth Lemke, Parks Canada

Jasper.

A weak and variable snowpack from recent strong winds and cold temps warrants a cautious approach. Identify features of concern.

Summary

Weather Forecast

Sunday will be cloudy with sun and flurries, trace snow, -20 to -13 and NE light winds. Monday will be a mix of sun and cloud, no snow, -19 to -14, and light Westerly wind. Tuesday will be sun and cloud, -16 to -11, and light SW winds.Â Wednesday will be cloudy and flurries, a trace of snow, -15 to -8, with light SW winds.

Snowpack Summary

Wind slabs and extensive wind effect is found in open areas. Recent warm temps and solar effect will have created a crust on solar aspects below treeline. The upper snowpack is a 50 to 80 cm thick slab that sits on three weak layers in the mid-pack. The entire snowpack is faceted after two weeks of cold, dry weather.

Avalanche Summary

Friday's road patrol to Sunwapta noted one giant cornice failure, the size of a bus, with no initiation below. No other naturals were noted in this immediate area. On Wednesday, isolated large Na avalanches were observed. One windslab from a cross loaded pocket on a W aspect and one persistent slab on an E aspect.Â

Confidence

Problems

Persistent Slabs

A slab up to 80cm thick overlies: weak faceted crystals (well developed in shallow areas), surface hoar (at, and just above treeline), and sun crusts ( on steep S and W aspects). Faceting has reduced slab strength below treeline and in shallow areas.

Be wary of slopes that did not previously avalanche.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3.5

Wind Slabs

Previous wind effect will be difficult to assess under new snow. Expect hardslabs in the alpine and at treeline. The cold has reduced the tension in these but caution is still warranted.

Best conditions on sheltered northerly aspects.If triggered the wind slabs may step down to deeper facet layers resulting in larger avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Mar 3rd, 2018 4:00PM