Avalanche Forecast

Issued: Mar 22nd, 2017 4:00PM

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

garth lemke, Parks Canada

Jasper.

We are in a low probability high consequence situation. The natural cycle has subsided yet any slope that did not run should be treated with utmost caution. Now is not to time to venture into big terrain. Sun can increase the danger quickly.

Summary

Weather Forecast

Thursday will be -3 to -6, light to moderate SW winds, clouds with some sun, and flurries. Friday will be much the same except for maybe more sun than cloud in the afternoon and -6 to -12 temperatures. Expect afternoon warming if sun comes out.

Snowpack Summary

Wind slabs up to 1.5m deep found at and above treeline. Large cornices are present. The mid-pack has several crusts and persistent instabilities of facets and surface hoar. Closer to the ground is a weak base around the November rain crust and depth hoar. Time is required for the snowpack to strengthen after Saturday's storm loading.

Avalanche Summary

No patrol Wednesday. Saturday and Sunday was a widespread cycle with crowns a kilometer long and 2m deep. Some were size 3.5 and ran full path stepping to basal layers near the ground. Less activity at treeline with size 2-2.5. Monday's control produced numerous size 3 avalanches from the alpine.

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Wind Slabs

60cm of storm snow over the past week has formed a dangerous and unpredictable windslab. Crowns up to 2m deep and a km long have been seen. Several of these stepped to ground and ran into the valley.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Use caution in lee areas in the alpine and treeline. Storm snow is forming touchy slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Cornices

Large cornices on lee features with some visibly detached. Those that may release would likely trigger a large avalanche. Give them a wide berth.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

The widespread observations and explosive work creating large and deep avalanches indicates that many went on this deep layer particularly where the snowpack is shallow and in rocky start zones. Involvement in one would be fatal consequences.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Be careful with low angle slopes that may not normally be a concern.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Mar 23rd, 2017 4:00PM