Archived

Avalanche Forecast

Feb 2nd, 2015–Feb 3rd, 2015

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

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: South Columbia.

A new storm slab is developing. Watch for continued loading from the forecast new snow and wind this week.

Confidence

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

Weather Forecast

Flurries overnight are expected to bring 3-5 cm by Tuesday morning. Tuesday and Wednesday should be mostly dry with a chance of light flurries. The next storm should start early Thursday morning and at this time looks like it could bring 10-15 cm by Friday morning.

Avalanche Summary

Some soft slab storm snow avalanches were reported on Sunday. I suspect that new storm snow avalanches were easy to trigger on Monday where the new snow was sitting on a hard crust and/or surface hoar that developed during the recent clear weather. Expect avalanche size to increase with incremental loading of the new storm slab later this week.

Snowpack Summary

Up to 30 cm of new snow overlies a variety of old surfaces. A crust formed last week at most elevations. In some places it was breakable in others it was supportive. A thin widespread layer of surface hoar lies above this crust. At the highest elevations the old surface was widely wind-affected. Deeper in the snowpack the mid-January surface hoar remains a concern. It can be found down between 40 and 100 cm. In some locations it has reportedly gained quite a bit of strength, but elsewhere it is still producing sudden (popping) failures in snowpack tests. This spatial variability means we'll have to keep an eye on it for a while yet. The mid-December surface hoar layer is now 80 to 140cm below the surface and has become unlikely to fail.

Avalanche Problems

Storm Slabs

New storm slabs have created a soft slab that may be easy to trigger in areas where the recent crust and/or a new layer of surface hoar are buried.

Be cautious of sluffing in steep terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3

Persistent Slabs

A layer of surface hoar buried in the upper meter of the snowpack remains a concern, especially at treeline and above. A large trigger, like an avalanche in motion could trigger a deeper persistent weakness.

Be aware of thin areas that may propagate to deeper instabilities.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 5