Archived

Avalanche Forecast

Nov 12th, 2015–Nov 13th, 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

Below Threshold

The avalanche danger rating below treeline will be below threshold

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

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

Regions: Glacier.

A natural avalanche cycle is headed our way. Be aware of changing conditions as the storm intensifies.

Weather Forecast

Rogers Pass looks like it will get thumped. Thursday night and into Friday we should see 30-40cm, strong/extreme SW ridge-top winds, and freezing levels rising to 1600m. Saturday is somewhat uncertain, but another 50cm may fall, with strong alpine winds and freezing levels around 1600m. Perfect conditions for a natural avalanche cycle!

Snowpack Summary

20-25cm of storm snow overlies widespread surface hoar at all elevations. SW winds have begun to create slabs in lee features at alpine and tree-line. As the load increases and the slabs become more cohesive, the surface hoar will become reactive. Rocks, stumps, and trees are still poking through the surface, so early season hazards still prevail.

Avalanche Summary

The size 3.5 avalanche off of Bruins Ridge on Sunday opened many eyes. Winter and, along with it, avalanche season are here. Yesterday, numerous loose and soft slab avalanches up to size 2.5 were observed on Mt MacDonald, pulling out of steep, alpine terrain.

Confidence

Due to the number of field observations

Avalanche Problems

Storm Slabs

The new snow overlies a widespread surface hoar layer. With increased loading (snowfall, wind transport) these slabs will become reactive.

Be cautious as you transition into wind affected terrain.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Wind Slabs

Soft wind slab exists at alpine and tree-line elevations after the weekend storm. They will be harder to see with the new snow. These slabs are propagating wide and running quite long distances.

Be aware of the potential for wide propagations.Avoid convexities or areas with a thin or variable snowpack.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Loose Dry

Steep gullies and confined chutes will concentrate your sluffs. Be aware of flowing loose snow if you are in one of these features.

Be aware of party members below you that may be exposed to your sluffs.Early season hazards such as rocks, trees and stumps are still visible.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2