Archived

Avalanche Forecast

Nov 25th, 2015–Nov 26th, 2015

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Glacier.

The Winter Permit System is now in effect. Be sure the area is open before you enter. Don't let the beautiful blue skies cloud your judgement today. Check the snow before dropping in.

Weather Forecast

The Arctic air has arrived, and temp's have dropped. Today, sunny weather will dominate, with light northerly winds and no precipitation in the next 4-5 days. Temp inversions are expected to develop over the next couple of days, with alpine temp's warming considerably while the valleys remain cool.

Snowpack Summary

Reverse-loading from strong northerly winds yesterday has created wind slabs on southerly aspects. These slabs overlie a variety of surfaces, including suncrust on steep S-SW aspects, with 2-3mm surface hoar on most other aspects. Below this, the snowpack as a whole is strengthening. A weak basal layer exists on alpine N/NE aspects.

Avalanche Summary

A skier-triggered size 2 from a SW aspect, at ~2200m, was reported in the McGill area yesterday: 30cm deep, 40m across, running 200m in length. Numerous natural-triggered size 2 to 3 slabs were observed from steep alpine terrain yesterday. These occurred during the strong northerly wind event and pulled out of north and south aspects.

Confidence

Due to the number of field observations

Avalanche Problems

Wind Slabs

Reverse-loading from N winds will have created slabs on southerly aspects. Previous wind slabs underneath are bonding, but remain vigilant when entering wind-effected areas.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Deep Persistent Slabs

On northerly alpine slopes, snow from early Sept was preserved and facetted forming a basal weakness. This may have been the failure plane on Swiss and Hermit Peak on the weekend.

Avoid shallow snowpack areas where triggering is more likely.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 3 - 4