Archived

Avalanche Forecast

Feb 20th, 2018–Feb 21st, 2018

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

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

Regions: Glacier.

Today there will be some obvious windslabs and Cornices out there. Bundle up and give yourself plenty of time to get back to the trail head.

Weather Forecast

Cloudy with sunny periods and isolated flurries. A trace of new snow will accumulate today and an Alpine high of -18c. Winds are currently light from the south and are expected to stay light throughout the day. Friday will be the first day of change in weather with 6-10cm in the forecast followed by flurries through the weekend.

Snowpack Summary

Strong NE winds have formed reverse loaded cornices that have been failing and triggering size 2 avalanches. Windslab can be expected in the alpine and exposed areas well into treeline. On solar aspects, a crust is buried 40cm. Persistent weak layers from January and December are now buried 150-200cm.

Avalanche Summary

The most notable avalanche yesterday was a skier controlled size 2(maybe 2.5) wind slab off Mt Sifton. We observed several avalanches yesterday that probably slid on the 18th. 3 cornice failures up to size 2.5, not pulling slabs or entraining mass. Another skier controlled size 1 in the Hermit slide path that presented as a loose dry avalanche.

Confidence

Due to the number of field observations

Avalanche Problems

Wind Slabs

Previous strong N-NE winds have formed reverse loaded windslab at and above treeline. Windslab avalanches to size 2.5 have been triggered by skiers or failing naturally. Avoid exposing yourself to overhead hazard.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1.5 - 2.5

Cornices

Cornices have been failing steadily over the past week. Cold temperatures and solar input are contributing to these failures with brittle fractures of the snow as temperatures fluctuate.

Avoid travel on slopes that are exposed to cornices overhead.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1.5 - 2.5

Persistent Slabs

Persistent weak layers continue to linger and are most likely triggered in steep, shallow, rocky, unsupported terrain features. Larger triggers such as cornice fall may also wake these deeper weak layers resulting in larger avalanches.

Avoid thin, rocky or unsupported slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2.5 - 3.5