Avalanche Forecast

Issued: Mar 27th, 2014 8:05AM

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

danyelle magnan, Parks Canada

Glacier.

Warm temps rapidly destabilized the snowpack yesterday, even through the clouds. More sun is expected today. Minimize your exposure to solar aspects, and to slopes with cornices overhead. Avalanches are traveling far and fast; regroup in safe spots!

Summary

Weather Forecast

The flurries should taper off this morning. We should see a mix of sun and cloud, with mild temps. As a result, we will likely see similar avalanche activity to yesterday. A weather system arriving on Friday will bring increasing cloud, westerly winds will become moderate, with up to 10cm by saturday morning. Saturday we may see some sun breaks.

Snowpack Summary

Yesterday's 20cm of new snow bonded poorly and became reactive with warm temps (see below), especially on solar aspects where it buried a sun crust. There are several crusts in the top meter which react with hard sudden results in tests. The Feb10 layer is down ~2m, shallower in thin areas, and continues to be a concern.

Avalanche Summary

Yesterday there were several reported of loose, moist avalanches triggered by skiers. They were easily triggered and entrained snow to size 2.5. They ran fast and and far, and into mature timber. Numerous natural avalanches also occurred from all aspects along highway corridor and in the backcountry. Most were size 2 but some were up to size 3.5.

Confidence

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

Problems

Storm Slabs

Yesterdays new snow bonded poorly to the snow below and became very reactive as the temps warmed up. Loose, moist avalanches were easily triggered by skiers. These avalanches were at the smallest "knee-twisters" but some grew to size 2.5.

Choose regroup spots carefully.Start on small terrain and slope-cut the top of slopes before riding them.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Persistent Slabs

Weak layers from early March, now buried a meter deep, are still reactive in tests. They are most likely to be triggered on solar aspects where sun crusts exist. Smaller avalanches may step down to these layers, resulting in a big avalanche.

Avoid shallow snowpack areas where triggering is more likely.Choose well supported terrain without convexities.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Deep Persistent Slabs

A persistent weak layer from late Jan/early Feb remains a serious concern as it continues to be responsible for very large avalanches. This layer is variable in its distribution, is now buried up to 2m deep, is hard to trigger, and harder to predict.

Avoid convexities or areas with a thin or variable snowpack.Resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 4

Valid until: Mar 28th, 2014 8:00AM