Archived

Avalanche Forecast

Nov 23rd, 2017–Nov 24th, 2017

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

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Glacier.

The Winter Permit System is in full effect. There will be Active Avalanche Control today in the Highway Corridor.

Weather Forecast

Rain and wet flurries today, as the atmospheric river or pineapple slowly departs Rogers Pass. Freezing levels will lower, winds will slowly decrease and precipitation will gradually subside. However currently we have a moderate rain fall, extreme winds and high freezing levels!

Snowpack Summary

150cm of new snow fell in the last seven days at tree line, followed by 40mm of rain. This combination has weakened the snowpack significantly. Below tree line the snowpack has become isothermal. At higher elevations storm and wind slabs have developed, and the upper snowpack layers are being saturated by the rain and warm temperatures.

Avalanche Summary

A large and destructive avalanche cycle started yesterday. The peak of this cycle will be this morning, with approximately 30-40mm of rain in the start zones over the last 24 hours. We've observed lots of loose wet avalanches in the highway corridor and slab avalanches. This is the largest and most significant cycle we've seen so far this winter.

Confidence

Avalanche Problems

Storm Slabs

Intense loading of start zones combined with warm temperatures and significant rain or snow fall, has created touchy storm slabs.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 3

Persistent Slabs

Rain penetrating the upper snowpack can percolate down to the halloween crust, awakening this layer.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 4

Loose Wet

We have observed many loose wet avalanches over the last 24 hours. This trend will continue until the temperatures cool significantly.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 3