Avalanche Forecast

Issued: Feb 13th, 2017 4:09PM

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

deryl kelly, Parks Canada

Jasper.

Warm alpine temperatures and flip-flops in the valley bottom. Rapid settlement of an already stressed snowpack likely to prolong this very active avalanche cycle.

Summary

Weather Forecast

SW-ly winds expected to again increase to moderate values for Tuesday with the arrival of the warm moist air. Alpine temps forecast to be near freezing with a mix of sun and cloud. Precip expected in the middle of the week with freezing levels to 2100m.

Snowpack Summary

Hard surface windslab in the alpine and open tree-line features. Recent HST in sheltered locations at tree-line and below forming a cohesive soft slab over a faceted mid-pack with only marginal support below tree-line. This is all sitting on a weak base of large facets and depth hoar to create an overall delicate and untrustworthy snowpack.

Avalanche Summary

Avalanche control on the Icefields Parkway and Maligne Lake road. Loaded lee features showing impressive propagation character up to size 3 in alpine targets. Previously controlled slopes two days prior were reloaded and ran again to size 2.5; burying the road more than a meter deep.

Confidence

Problems

Wind Slabs

Hard touchy windslab in the alpine and open tree-line features showing very serious potential for wide propagation in connected features.

Be aware of the potential for wide propagations due to the presence of hard windslabs.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Storm Slabs

30-40cm of storm snow has formed a touchy storm slab.

Use caution on open slopes and convex rolls

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

Avalanches initiated within the storm snow may step down to deeper layers and in some cases gouging to ground in thin snowpack areas.

Be aware of thin areas that may propogate to deeper instabilites.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Feb 14th, 2017 4:00PM