Avalanche Forecast

Issued: Mar 1st, 2013 8:31AM

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

Danyelle Magnan, Parks Canada

Glacier.

A large natural avalanche cycle is occurring and the storm is just beginning. Avoid all avalanche terrain.

Summary

Weather Forecast

The "pineapple express" is just hitting us. Lots of precipitation, mild temps and high alpine winds are forecast over the weekend. Up to 40cm are expected over the next 24hrs. Freezing levels may rise to 1600m, and southerly winds in the alpine may reach 125km/hr today. The intense loading will rapidly cause danger to rise.

Snowpack Summary

Nearly 30cm of heavy, and moist at lower elevations, snow has fallen in the last 12 hours. This has rapidly loaded the Feb 12 surface hoar and crust layers which are now down 80 to 90cm. This layer is most prevalent at and below treeline. In the alpine, southerly winds are transporting snow rapidly loading slopes and forming new windslabs.

Avalanche Summary

A natural avalanche cycle is just beginning as the storm hits. Rapid loading by snow and moderate S'ly winds are triggering avalanches. Large natural avalanches to size 3 have been observed along the highway running to valley bottom. Precip rates and wind speeds will increase today; expect natural avalanches to run full path in the backcountry.

Confidence

Problems

Storm Slabs

Rapid loading by snow and wind is overloading the snowpack. Expect widespread natural avalanche activity, with large avalanches running into valley bottoms. Avalanches may step down to deeper persistent weak layers.

It is a good time to stay within the boundaries of a ski resort.Avoid all avalanche terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

2 - 3

Persistent Slabs

A weak surface hoar layer is now down ~85cm. This layer has been triggered by humans; remotely from 40m away, and capable of wide propagations up to 150m. Rapid loading or other avalanches may trigger this layer and produce very large avalanches.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 4

Valid until: Mar 2nd, 2013 8:00AM