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Archived

Avalanche Forecast

Feb 5th, 2020–Feb 6th, 2020
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
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: Northwest Inland.

Triggering large avalanches remains a concern as we leave a period of stormy weather.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength. Recent weather patterns have resulted in a high degree of snowpack variability within the region.

Weather Forecast

WEDNESDAY NIGHT: Cloudy with isolated flurries and trace accumulations, moderate wind from the west, alpine temperatures drop to -8 C.

THURSDAY: Cloudy with scattered flurries and 5-10 cm of new snow, light wind from the northwest, alpine high temperatures around -6 C.

FRIDAY: Mostly sunny, light wind, alpine high temperatures around -8 C.

SATURDAY: Sunny, light wind, alpine high temperatures around -8 C.

Avalanche Summary

A few large persistent slab avalanches have been triggered in the past few days. On Monday, a size 3 slab avalanche was triggered by a snowmobiler in the Seaton area on a steep northeast-facing slope at 1800 m. The avalanche crown was 100-150 cm thick and ran on basal facets. On Saturday a large snow machine remotely triggered a size 3.5 avalanche in the Kispiox area. The avalanche crown was 50-200 cm thick and ran on buried surface hoar. These events highlight how the recent storms have made buried weak layers more reactive.

Storms over the past week have also resulted in several cycles of natural avalanche activity. Most recently, small to large (size 1-2.5) slab avalanches were reported across the region on Monday and Tuesday, including some in this MIN report from Hankin. Most of the natural avalanche activity was on east-facing slopes that were wind loaded.

Snowpack Summary

10-30 cm of recent snow has rapidly settled due to mild temperatures. In open terrain this snow has been dramatically affected by strong wind from the southwest. Some areas continue to have issues with weak layers that formed during cold weather in January. Depending on location these layers may be composed of soft facets or surface hoar and are typically are buried 60-120 cm below the surface. Crust/facet layers also lurk at the base of the snowpack, especially in shallower (eastern) areas. Most recent signs of instability with these deeper layers have been around Hazelton and Kispiox, but could be a problem on certain slopes anywhere in the region. 

Terrain and Travel

  • Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Avalanche Problems

Wind Slabs

Recent storm snow is gradually gaining strength, but will likely remain reactive on wind loaded slopes.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Persistent Slabs

Recent storms have agitated buried weak layers, resulting in some very large persistent slab avalanches. Although these avalanches are only possible in isolated locations, the consequences are severe. Recent areas of concern have been around Kispiox and Hazelton, but any large steep slope should be approached with caution.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3