Archived

Avalanche Forecast

Dec 5th, 2012–Dec 6th, 2012

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

3: Considerable

The avalanche danger rating below treeline will be considerable

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

3: Considerable

The avalanche danger rating below treeline will be considerable

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: Glacier.

High winds have created avalanche conditions. Be alert when crossing avalanche paths, naturally triggered avalanches from above may run to valley bottom.

Weather Forecast

Today flurries and cloudy conditions can be expected, with freeze lines staying below the elevation of the pass. Strong winds this morning will ease to moderate tonight and into tomorrow.

Snowpack Summary

A 60cm storm slab is becoming increasingly cohesive.Nov28 layer which will be most reactive where it overlies a crust on S slopes or where surface hoar was buried; sheltered areas at treeline. The Nov 6 crust may become reactive with increasing load.

Avalanche Summary

Yesterday, distinct avalanche cycles occurred during periods of intense wind and snowfall. 1 size 3 and 22 size 2-2.5 natural avalanches were observed from paths adjacent to the highway, east of Rogers Pass. These all occurred from steep terrain...

Confidence

Avalanche Problems

Wind Slabs

Strong S-SW winds have loaded lee slopes, triggering natural avalanches in steep terrain. Expect touchy loaded pockets, and soft windslabs on lee slopes. Strong forcast winds will enhance this problem.

Be cautious as you transition into wind affected terrain.Stay off recent wind loaded areas until the slope has had a chance to stabilize.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 3

Storm Slabs

We've received 90cm of snow on top of this layer at treeline which has settled into about 65cm of storm slab which will be most reactive where it buried surface hoar or sun-crust.

Sluffs may trigger deeper instabilities.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Persistent Slabs

The Nov 6 crust complex has yet to wake up. While the likelihood of triggering is low, it will produce large avalanches. As the load on this layer increases, it may become reactive. Smaller avalanches may step down to this deeper layer.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4