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Archived

Avalanche Forecast

Feb 1st, 2021–Feb 2nd, 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
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Coastal.

Wind slabs at upper elevations continue to be touchy to skier and rider triggers, especially where they sit above a buried surface hoar/ crust layer.

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

Tuesday: A mix of sun and cloud with isolated flurries. Ridgetop wind light from the northeast. Alpine temperatures near -6 and freezing levels valley bottom. 

Wednesday: Snow 5 cm with light ridgetop wind. Alpine temperatures near -6 and freezing levels in the valley bottom.

Thursday: Snow up to 20 cm. Ridgetop wind strong from the southwest and freezing levels rising to 1300 m. 

Avalanche Summary

Several small wind slab avalanches were triggered by skiers and riders at treeline and in the alpine on various aspects on Saturday and Sunday (see this MIN report). 

As the slab properties start to change, and the recent snow becomes more cohesive (under the influence of wind and settlement) it will likely remain reactive to human triggers, especially where it sits above a surface hoar interface. 

Snowpack Summary

15-45 cm of recent snow sits on a crust below 1000 m and surface hoar in sheltered locations at and below treeline. If the recent snow has enough cohesion the slab may be reactive where it sits above these weak layers. This MIN report shows just that.

The layers in the mid and base of the snowpack have gained strength with high snowfall amounts in January. Deeper layers appear to have gone inactive in the southern part of the region. However, in the northern part of the region (e.g. Bear Pass, Ningunsaw) there has still been regular avalanche activity on weak snow at the bottom of the snowpack with large loads such as explosives or cornice collapses.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Watch your sluff: it may run faster and further than you expect.

Avalanche Problems

Wind Slabs

Moderate southerly wind continues to redistribute the new snow and build fresh wind slabs in lee terrain features in the alpine and exposed treeline. Older wind slabs were formed on westerly aspects and may still be reactive. Wind slabs will be particularly reactive anywhere snow overlies buried surface hoar or crust. The surface hoar layer is likely preserved in sheltered areas at and below treeline. In steep and wind-protected areas loose dry snow avalanches (sluffs) are expected. 

Aspects: North, North East, East, South East, West, North West.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2.5