Avalanche Forecast

Issued: Feb 3rd, 2016 4:05PM

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

Max Darrah, Parks Canada

Jasper.

Although most of the avalanche activity observed on Wednesday was in the alpine, concern still exists for isolated areas at treeline where a touchy interface has caused some dramatic propagations and close calls in the past week.

Summary

Weather Forecast

Cool temperatures, with freezing levels remaining below 1000m for Wednesday then a gradual warming trend towards the weekend. Southwest wind, gusting to moderate. Light scattered flurries amounting to less than 5cm by Friday evening, increasing in intensity over the weekend with some models showing as much as 25cm.

Snowpack Summary

New windslabs have formed in the alpine and at treeline, mainly on North Easterly aspects below ridge crests and cross loaded terrain. These slabs add load to a mainly weak and facetted midpack that has a layer of concern down about 60cm at an interface of facets and new snow. Isolated pockets of decomposing surface hoar at treeline down 40cm.

Avalanche Summary

Lots of natural avalanche activity on Wednesday, mainly slab avalanches to size 2 on steep solar aspects between 1500 - 2500m, as well as numerous point releases to size 1.5, mainly on Westerly aspects.

Confidence

Due to the number of field observations

Problems

Wind Slabs

New soft windslab forming on lee and cross loaded terrain. This is in addition to windslabs up to 80cm thick formed during the storm at the end of last week.

Be aware of the potential for wide propagations due to the presence of hard windslabs.Caution in lee and cross-loaded terrain near ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

35cm of storm snow from Thursday has formed a slab overlying a weak facetted snowpack. Field teams are finding decomposed surface hoar and sudden planar test results in isolated locations at treeline. This is the key interface to assess.

Be aware of thin areas that may propogate to deeper instabilites.Use caution on open slopes and convex rolls at treeline where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Feb 4th, 2016 4:00PM