Archived

Avalanche Forecast

Dec 2nd, 2017–Dec 3rd, 2017

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

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

2: Moderate

The avalanche danger rating in the alpine will be moderate

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

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Inland.

Reactive wind slabs may exist at upper elevations and could step down to deeper weak layers producing large avalanches. Use a conservative approach to terrain selection as the snowpack remains highly variable in the region.

Confidence

Low - Due to the number and quality of field observations

Weather Forecast

Sunday: Mix of sun and valley cloud. Ridgetop winds light from the North West. Alpine temperatures near -6 and freezing levels at valley bottom. Monday: Mostly cloudy. Alpine temperatures near -3 freezing levels rising to 1000 m. Ridgetop winds strong from the West.Tuesday: Mostly cloudy. Alpine temperatures near 0 degrees and freezing levels 1500 m. Ridgetop winds light from the South West.Expect temperature inversions from Monday onward. Check out the Mountain Weather Forecast for details.

Avalanche Summary

No recent avalanche activity has been reported. Stiff wind slabs may exist at treeline and in the alpine on leeward slopes and cross-loaded features. If triggered, these could step down and trigger deeper weak layers, initiating large avalanches. The last significant avalanche observation was submitted on November 28th from Skilokis Cr. A size 2.5 persistent slab was triggered from 150 m distance away. This problem will likely linger. Check out the Mountain Information Network for more details. Give info, get info.

Snowpack Summary

Alpine snow surfaces are likely wind affected with average snowpack depths 80 cm -140 cm at treeline elevations, and up to 160 cm in the alpine. Approximately 30-50 cm of recent snow now overlies two crusts that were buried near the end of November. Reports indicate that these crusts extend well into the alpine. Below these crusts exists a well settled mid pack overlying the late October crust near the base of the snowpack. This late October "crust/facet combo" is widespread and has been reactive to rider triggers producing large avalanches.

Avalanche Problems

Deep Persistent Slabs

The late October crust lies near the base of the snowpack with a thin layer of weak, sugary snow above it. Recently, this layer has been reactive to rider triggers and remote triggering has occurred producing a large avalanche.

Be cautious in shallow snowpack areas where triggering a deeper layer may be possible.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3

Wind Slabs

Recent snow and wind have formed touchy wind slabs. Expect these slabs to be more pronounced at higher elevations and on leeward aspects. Signs of wind affected snow include whumpfing and cracking.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Caution around convexities, slopes or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2