Avalanche Forecast

Issued: Feb 11th, 2022 4:00PM

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

Avalanche Canada bchristie, Avalanche Canada

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Dynamic weather requires dynamic decision making. Current snowpack conditions vary with elevation, and could change through the day with above zero temperatures and sunshine. Keep a constant watch for signs of instability and prepare for challenging travel.

Summary

Confidence

High - We have a good understanding of the snowpack structure and confidence in the weather forecast

Weather Forecast

Freezing levels will vary greatly across the region. Expect as high as 2000 m around smithers, lower as you look further north, and as low as 500 m around Ningunsaw.

FRIDAY NIGHT: Mostly clear in Smithers and south, mostly cloudy north of Smithers. 0-2 cm of snow expected. Moderate to strong west wind. Possible above freezing layer making for temperatures above 0 °C between 1200 and 2200 m in the southern end of the region. 

SATURDAY: Mostly clear in Smithers and south, mostly cloudy north of Smithers. 0-2 cm of snow expected. Strong west wind. Possible above freezing layer making for temperatures above 0 °C between 1200 and 2200 m in the southern end of the region. 

SUNDAY: Mostly cloudy. 0-2 cm of snow expected. Light southwest wind. Above freezing layer breaking down, freezing levels around 750 m. 

MONDAY: Partly cloudy. Possible trace of snow expected. Moderate northwest wind. Freezing levels at valley bottom in the morning, rising as high as 1000 m in the south of the region. 

Avalanche Summary

No new avalanches were reported on Friday before 4 pm.

On Wednesday, a warm, wet, windy storm produced a natural avalanche cycle, with numerous large avalanches reported (up to size 3.5). During the height of the storm, most avalanches were reported as loose wet, wet slabs, and glide slabs. In areas where the freezing level was lower (in the north of the region), some avalanches started as wind slabs or cornice falls, and became loose wet as they ran to lower elevations. As the temperature cooled overnight, avalanche activity continued, with large, natural, wind slab and cornice triggered avalanches occuring through until Thursday morning. 

Snowpack Summary

Below 2000 m (1000 m in the north end of the region), 10-30 mm of rain fell throughout the day on Wednesday, soaking the upper snowpack. In most places, a firm crust has formed on the surface. At treeline, this crust may be supportive to skis and snowshoes, but breakable under a snowmobile or a boot. Below treeline, the crust is thinner, weaker, and overlies moist snow.

Above 2000 m in the southern end of the region there are areas that received up to 30cm of snow, but observations so far suggest that this terrain was hammered by the wind, scouring some terrain and forming unreactive wind effected surfaces elsewhere.

See here for a summary of the conditions on Thursday in the Microwave area from our field team.

In the northern end of the region, where there was still dry snow available for transport, Thursday's wind formed reactive windslabs and cornices in the alpine. 

In some areas a combination of two thin crusts with faceting above and below exists 40 to 50 cm deep. Deeper in the snowpack, two weak layers may exist around 60 to 120 cm deep. The first is a surface hoar layer from mid-January and the second is a layer of faceted snow from early January. These layers haven't produced recent avalanches, but they are producing concerning results in snowpack tests, and the potential remains until these layers bond to the snowpack.

Terrain and Travel

  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
  • A crust on the surface will help bind the snow together, but may make for tough travel conditions.
  • Be alert to conditions that change with elevation and sun exposure.
  • Although their spatial distribution is isolated, wind slabs are reactive.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.

Problems

Wind Slabs

An icon showing Wind Slabs

Terrain that didn't get rained on during Wednesday's storm still holds dry, cold snow, and moderate to strong winds have varied in direction the last few days.

If the snow seems soft and dry, watch out for signs of instability like shooting cracks, or hollow, drum-like sounds, and use extra caution around ridge crests and on convex rolls. 

Cornices have been reported to be quite large, and they could become weak with above zero temperatures and daytime sun, so use extra caution when travelling around or underneath them. 

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

An icon showing Loose Wet

The south end of the region will see sunny skies again on Saturday, and temperatures warmer than zero into the alpine. 

Be cautious around steep slopes that are in the sun, unless you are sure the snow surface is a thick, frozen crust.

This problem will be less likely in the northern half of the region, where it should be cloudier and colder.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 12th, 2022 4:00PM