Avalanche Forecast

Issued: Feb 7th, 2020 5:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Persistent Slabs and Wind Slabs.

Avalanche Canada ghelgeson, Avalanche Canada

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Certain slopes have potential for large persistent slab avalanches and the strengthening February sun may have a destabilizing affect. Carefully evaluate the snowpack and terrain before committing to avalanche terrain.

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

We’re moving into a rather benign weather window for the next few days highlighted by clear skies and potentially strong wind for the later half of the weekend.

FRIDAY NIGHT: Freezing level at valley bottom, light northeast wind at most elevations, no significant precipitation expected.

SATURDAY: Clear skies, freezing level at valley bottom, moderate northwest wind that ramps up to strong northwest in the afternoon, no significant precipitation expected.

SUNDAY: Broken cloud cover, freezing level around 500 m, strong northwest wind, no significant precipitation expected.

MONDAY: Scattered cloud cover, freezing level around 800 m, moderate to strong west/northwest wind, no significant precipitation expected.

Avalanche Summary

On Thursday human triggered wind slabs to size 1.5 were reported at and above treeline on north and east aspects. Loose dry avalanches were also reported on steep south facing features below treeline. Some very large persistent avalanches have been reported over the past week. A size 3 avalanche was triggered by a snowmobiler in the Seaton area on Monday (northeast slope at 1800 m) and a size 3.5 avalanche was remotely triggered by a large snow machine near Kispiox on Saturday (southeast slope at 1700 m). Then on Wednesday, several size 2-3 avalanches were naturally triggered due to strong wind and mild temperatures. These avalanches have ran on both buried surface hoar layers and crust/facets at the bottom of the snowpack.

Some smaller (size 1) wind slabs were also triggered by riders on Wednesday.

Snowpack Summary

Open terrain has been heavily affected by strong wind from the west. Crusts can be found on the surface up to roughly 1200 m and on open south-facing slopes. 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. The most recent signs of instability with these deeper layers have been around Hazelton and Kispiox, but persistent weak layers could be a problem on 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.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
  • Be alert to conditions that change with elevation and sun exposure.

Problems

Persistent Slabs

An icon showing 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

Unlikely - Possible

Expected Size

2.5 - 3.5

Wind Slabs

An icon showing Wind Slabs

Recent storm snow is gradually gaining strength, but may remain reactive on steep wind loaded and sun-exposed slopes.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 8th, 2020 5:00PM