Avalanche Forecast

Issued: Feb 4th, 2016 4:00PM

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.

a.l. horton, Parks Canada

Jasper.

The best skiing will be found on sheltered tree-line slopes but remember that a touchy interface exists between the new snow slab and old facets. There have been dramatic propagations and close calls in the past week.

Summary

Weather Forecast

Light snow through Friday with 10+ cm possible by Sunday.Â Freezing levels forecasted between 1300 and 1600 m then cooling slightly on Sunday.Â Wind will be a player with Moderate to Strong SW winds expected with the new snow on Saturday.

Snowpack Summary

Wind slab continues to form at tree-line and above on North-Easterly aspects below ridge crests and cross-loaded terrain. These slabs are loading a weak and facetted mid-pack that has a layer of concern down about 60cm at the interface between old facets and new snow. Isolated pockets of decomposing surface hoar at tree-line 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.Â No avalanche patrol on Thursday.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Friday

Problems

Wind Slabs

Wind slab forming on lee and cross-loaded terrain. This is in addition to wind slabs up to 80cm thick formed during the storm at the end of last week.

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

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 last week has formed a slab overlying a weak facetted snowpack. Field teams have found decomposed surface hoar with sudden planar test results in isolated locations at tree line. This is the key interface to assess.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Feb 5th, 2016 4:00PM