Avalanche Forecast

Issued: Jan 19th, 2018 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.

max darrah, Parks Canada

Jasper.

Ski quality has improved with the new snow. Careful slope evaluation is essential right now to assess whether or not this new snow is sitting on a well preserved surface hoar layer in the top 15cm of the snowpack.

Summary

Weather Forecast

Snowfall amounts tapering off steadily, with only light scattered flurries expected through the weekend, perhaps adding another 5-10cm. Alpine temperatures will continue to cool, dipping down to -15C. Winds decreasing and returning to the light range, gusting moderate from the Southwest.

Snowpack Summary

10cm of new snow has been pushed around by recent moderate SW winds, forming new windslabs in the alpine. This new snow covers a couple interesting surface hoar layers in the top portion of the snowpack - Jan 7 (5-10mm well preserved) and Jan 17 (2-5mm). These layers may present a touchy interface for new windslabs and storm snow.

Avalanche Summary

Limited visibility, but field teams report several natural slab avalanches to sz 2, originating in the alpine and running to the bottom of the track. The Jan 7 surface hoar layer was reactive to skier traffic, and ski cutting produced numerous sz 1 wind slabs in the Hilda Creek area. More activity is expected on the Jan 7 layer over the next while.

Confidence

Due to the number of field observations

Problems

Wind Slabs

5-10cm of storm snow has been pushed into fresh windslabs. The concern is for areas where these slabs overlay a couple layers of surface hoar in the top 30cm of the snowpack. Field teams found touchy new slabs in the Hilda Creek drainage.

Use caution on open slopes and convex rolls at treeline where buried surface hoar may be preserved.Use caution in lee areas. Recent wind loading has created fresh slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Persistent Slabs

There are 3 distinct surface hoar layers in the top 40cm of the snowpack. These layers are expected to become more reactive to natural and human triggers with the additional snow load leading into the weekend.

Use caution on open slopes and convex rolls at treeline where buried surface hoar may be preserved.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 20th, 2018 4:00PM