Archived

Avalanche Forecast

Dec 2nd, 2022–Dec 3rd, 2022

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

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

Regions: Dogtooth, East Purcell, Purcells.

Snowpack is generally weak, thin, and sugary. The main avalanche hazard exists in areas where a cohesive slab has formed on top of a weak lower snowpack.

Confidence

Moderate

Avalanche Summary

A small (size 1) slab avalanche was observed Thursday in the upper below treeline region (~2000 m), on a steep, south-facing road bank. It failed and propagated on the sugary, faceted lower snowpack, down 25 cm from the surface.

Snowpack Summary

The surface snow continues to dry out (facet) with the current cold temperatures and is being redistributed by variable winds. In the alpine and treeline, much of the wind-exposed terrain has been scoured of snow. In deeper snowpack (loaded) areas, cohesive wind slabs may exist and generally overlie a weak, sugary, facetted lower snowpack.

The overall height of snow is highly variable throughout the region. 50-150 cm in the alpine.

Weather Summary

Friday night

Mostly cloudy with no precipitation expected, light to moderate westerly ridgetop winds, and alpine temperatures in the -15 to -20 C range.

Saturday

Clearing throughout the day. Generally light winds from the west at ridgetop, with alpine temperatures warming slightly, in the -10 to -15 C range.

Sunday

Mostly sunny, light ridgetop winds and alpine temperatures around -10 C.

Monday

Mostly sunny, light ridgetop winds and alpine temperatures around -15 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Expect slab conditions to change drastically as you move into wind exposed terrain.
Carefully evaluate steep lines for wind slabs.
Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

Avalanche Problems

Wind Slabs

Wind slabs have formed behind ribs and ridges in the alpine and treeline. These cohesive slabs likely overlay a weak, sugary lower snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

A buried surface hoar, facet layer is beginning to become a greater hazard as snow amounts reach threshold below treeline. It will be most reactive where the upper snowpack has settled into a cohesive slab.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1 - 1.5