Archived

Avalanche Forecast

Dec 30th, 2021–Dec 31st, 2021

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

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

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: North Rockies.

Assess for wind slabs, which could be triggered in steep terrain.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

THURSDAY NIGHT: Partly cloudy with no precipitation, 10 to 20 km/h northeast wind, alpine temperature -23 C.

FRIDAY: Partly cloudy with no precipitation, 10 to 20 km/h northwest wind, alpine temperature -21 C.

SATURDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 60 to 90 km/h southwest wind, alpine temperature -14 C.

SUNDAY: Cloudy with snowfall, accumulation 5 to 15 cm, 20 to 40 km/h southwest wind, alpine temperature -13 C.

Avalanche Summary

No recent avalanches have been observed in the North Rockies.

We'd appreciate if you submit your observations to the Mountain Information Network, even just a photo.

Snowpack Summary

Wind slabs may have formed from Wednesday night's 5 cm of snow and strong wind from variable directions. These slabs could remain touchy to riders, as they sit on previously wind-affected snow, sugary faceted grains, and/or surface hoar in areas sheltered from the wind.

A weak layer of feathery surface hoar may be found around 20 to 50 cm deep. It is most likely found in sheltered terrain features in the lower alpine and treeline, or open features below treeline (e.g., cut blocks). We've only received a few reports of this layer, so it may be spotty in the region.

The middle of the snowpack has been reported as well-settled and strong. The base of the snowpack is composed of weak faceted grains, particularly in thin snowpack areas east of the divide, but has not recently been a concern.

Terrain and Travel

Carefully evaluate steep lines for wind slabs.
Make observations and assess conditions continually as you travel.

Avalanche Problems

Wind Slabs

Wind slabs may exist in steep terrain features. They may be found on all aspects, including south, due to variable wind directions. These slabs may be touchy to riders and could take some time to bond to the snowpack.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2