Avalanche Forecast

Issued: Feb 21st, 2014 8:20AM

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

danyelle magnan, Parks Canada

Glacier.

It's not the time to let your guard down. The skiing is great, but the consequences of reading the terrain wrong are high. Be vigilant in choosing simple, low-angled and well supported terrain without overhead hazard. The snow's good there too!

Summary

Weather Forecast

Unsettled weather is expected through the weekend. Expect mostly cloudy skies with sunny periods and isolated flurries, cool temps of -10 to -20 and gusty westerly winds at ridgetop. The sunny periods are a concern as the new storm snow will become more reactive with the initial hit from the sun.

Snowpack Summary

1-1.4m of storm snow is settling into a cohesive slab over the Feb 10 facet/surface hoar/crust interface. Snowpack tests give spooky results and indicate that the Feb 10 PWL is triggerable with a propensity to propagate. In addition, layers in the top 60cm of the storm slab are reactive and if triggered will likely step down to the Feb 10.

Avalanche Summary

Yesterday 2 size 3's and 7 size 2-2.5 avalanches were observed along the highway. Many running right to avalanche fans. And on Wednesday, a significant event west of the park saw wind blast from a slide from extreme terrain knock down 150 year-old timber. Less cracking and whumphing is being observed while traveling but the layers remain reactive.

Confidence

Problems

Persistent Slabs

This problem is becoming increasingly challenging. The clues of instability, like cracking and whumphing are tapering off, but tests and continued avalanches indicate that this thick slab is triggerable and will produce very large avalanches.

Avoid areas with overhead hazard.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Wind Slabs

Winds during the last week have transported the new snow, loading lee slopes and forming cohesive wind slabs. In areas where the snow is more cohesive, triggering of these slabs is likely. If triggered these slabs will likely step down deeper.

Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Cornices

Yesterday, a slab 1-1.5 meters deep was observed that was triggered by cornice failure. Large cornices exist along ridges, and are may fail with fluctuating temperatures and sunny periods. These are big triggers that could initiate BIG avalanches.

Pay attention to overhead hazards like cornices.Do not travel on slopes that are exposed to cornices overhead.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Feb 22nd, 2014 8:00AM