Archived

Avalanche Forecast

Nov 25th, 2017–Nov 26th, 2017

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

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

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

Regions: South Columbia.

Consider avalanche danger to be HIGH in areas that receive rain on top of 30 cm or more of dry snow. Avoid exposure to avalanche terrain during periods of rapid loading by rain, snow, or wind.

Confidence

Low - Freezing levels are uncertain

Weather Forecast

SUNDAY: 10-20mm rain or snow depending on elevation / Moderate to strong westerly ridgetop winds / Freezing level rising to around 2400 mMONDAY: Cloudy with isolated flurries / Light to moderate westerly ridgetop winds / Freezing level around 1200 mTUESDAY: 5-10 cm of snow / Light to moderate westerly ridgetop winds / Freezing level around 1500 m

Avalanche Summary

On Friday, no new avalanches were reported in this region. Natural avalanche cycle expected on Sunday in areas where rain falls on dry snow. We currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

10 to 20 cm of recent snow and moderate to strong winds have likely formed wind slabs on lee features at treeline and above. The new snow sits on a thick crust formed by the rain that fell to mountain tops on Wednesday and Thursday. The heavy rain has rapidly shrunk the snowpack and has transitioned much of the snowpack from dry to moist snow. The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 200+cm in the alpine, 100-150cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks. The major feature in the snowpack is a crust which was formed around Halloween and can be found approximately 100cm down at treeline elevations. We currently have very limited snowpack observations within this region and it is critical to supplement this information with your own observations.

Avalanche Problems

Storm Slabs

Natural avalanche cycle expected on Sunday in areas where rain falls on dry snow.

Avoid exposure to avalanche terrain during periods of rapid loading by rain, snow, or wind.Watch for signs of instability such as whumpfing, cracking, or recent natural avalanches.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 3

Loose Wet

Rain falling on dry snow can quickly trigger natural avalanches.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 2

Persistent Slabs

Rapid loading by rain or snow will increase the likelihood of avalanches occurring on this layer.

Avoid exposure to avalanche terrain during periods of rapid loading by rain, snow, or wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3