Archived

Avalanche Forecast

Dec 10th, 2014–Dec 11th, 2014

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

4: High

The avalanche danger rating below treeline will be high

Alpine

4: High

The avalanche danger rating in the alpine will be high

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

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Glacier.

An intense storm is causing dangerous backcountry conditions (and terrible ski quality). Avoid all avalanche terrain and give the snowpack some time to adjust to the new load in the wake of the storm.

Weather Forecast

The forecast is warm, wet and windy; avalanche hazard will increase. Freezing levels today are around 2300m, with up to 15mm of rain, alpine temps of +3'C and S winds gusting to 85km/hr. Overnight, freezing levels should lower to 1300m and up to 10cm of snow are expected. Thurs and Fri will be cloudy with flurries, moderate SW winds, highs of +1.

Snowpack Summary

A ~25cm storm slab, which will be thicker in windloaded areas, will bond poorly where it overlies surface hoar or sun crust. Below 1600m it will bond poorly to a rain crust. Rain, occurring to at least 1900m is adding more load. The Nov persistent weak layers, down ~105 and ~140cm, still have the potential to create large avalanches.

Avalanche Summary

Natural avalanche activity started yesterday, with numerous size 2-2.5 avalanches occurring from all aspects and running onto avalanche fans. By the end of the day avalanche debris was becoming wet in character. Widespread avalanche activity is expected today due to rapid loading by rain and wind.

Confidence

Avalanche Problems

Storm Slabs

A heavy storm slab is building rapidly with moderate precipitation, warm temps and strong winds. It will bond poorly to the snow below and natural avalanches are occurring. Storm slabs may step down deeper resulting in very large avalanches.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 2 - 3

Persistent Slabs

Persistent weak layers that were very reactive earlier this season are expected to wake up again with the rapid loading that is occurring. These layers are capable of wide propagations and producing very large and destructive avalanches.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Loose Wet

Rain to at least 1900m is saturating and weakening the snow. Below 1600m the wet surface snow will slide easily on buried crusts.

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: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3