Archived

Avalanche Forecast

Dec 30th, 2021–Dec 31st, 2021

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

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: North Columbia.

Keep your eyes open for wind slabs in steep terrain features. There still remains the possibility of triggering a buried weak layer.

Confidence

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

THURSDAY NIGHT: Partly cloudy with no precipitation, 10 to 20 km/h north wind, alpine temperature -22 C.

FRIDAY: Clear skies with no precipitation, 10 to 20 km/h north wind, alpine temperature -22 C.

SATURDAY: Cloudy with snowfall, accumulation 2 to 5 cm, 20 to 40 km/h southwest wind, alpine temperature -18 C.

SUNDAY: Cloudy with snowfall, accumulation 10 to 20 cm, 30 to 60 km/h southwest wind, alpine temperature -14 C.

Avalanche Summary

A few small wind slab avalanches were observed in steep alpine terrain on Wednesday.

The latest avalanche activity on the early-December weak layer described in the snowpack summary was from Monday. This included two natural avalanches and one triggered by a rider. They were large (size 2 to 3), observed on all aspects, and found between 1700 m and up to 2600 m.

Snowpack Summary

Thin wind slabs may have formed from Wednesday night's 5 cm of snow and variable wind. 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 30 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). Although avalanche activity hasn't been prominent on this layer, it has been reactive in snowpack tests.

Sugary faceted grains may be found around the early-December melt-freeze crust 80 to 150 cm deep. The layer is most prevalent around 1700 m to 2200 m but could exist at lower and higher elevations for sections of the region. This layer is spatially variable, with many areas showing good bonding to the crust whereas other areas showing concern. This layer has recently been most reactive where it remains shallower than about 100 cm.

Terrain and Travel

Carefully evaluate steep lines for wind slabs.
Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
Be aware of the potential for large avalanches due to the presence of a persistent slab.

Avalanche Problems

Wind Slabs

Wind slabs may be found in steep, wind-exposed terrain. These slabs may remain triggerable by riders, as they may sit on weak faceted snow or surface hoar crystals.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

We continue to receive sporadic reports of people triggering a weak layer of faceted grains around a melt-freeze crust that formed in early December. This layer is found around 80 to 150 cm deep and is most common at elevations between 1700 m and 2200 m. Read more about it here.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3.5