Avalanche Forecast

Issued: Feb 11th, 2021 3:00PM

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

Avalanche Canada jcoulter, Avalanche Canada

 

Wind and extreme cold is not a fun combo! Be mindful of wind loaded features and use a conservative mindset when planning objectives in these temperatures.

Summary

Confidence

Moderate -

Weather Forecast

THURSDAY NIGHT - Sunny / strong to extreme south east wind / alpine high temperature near -16

FRIDAY - Increasing cloud later in day / strong to extreme south east wind / alpine high temperature near -12

SATURDAY- Cloudy / strong variable wind / highs near -12

SUNDAY - Overcast, possible snow, strong south wind, highs near -9

Avalanche Summary

On Wednesday in the Terrace vicinity, natural wind slabs to size 2 were reported on various aspects. Wind slabs were also reactive to ski cutting and there was one small skier accidental reported (no involvement).

In the south west of the region where outflow winds have been the strongest, there was a bigger cycle with natural and explosives triggered size 2-3.5.  

On Tuesday wind slabs up to size 2 were reported by various operators. The northern part of the region had the biggest reported events with windslabs up to size 2.5 on the late January interface.

On Monday, skiers were able trigger unsupported pillows failing on surface hoar down 25-40 cm near Terrace. In the north of the region, skiers found reactive wind slabs in immediate lee features in the alpine. 

Snowpack Summary

Continued outflow winds are building wind slabs (where snow is just not sublimating) and reverse loading features. Hard slabs, scoured slopes and sastrugi will be present where outflow effects are the strongest. In more sheltered zones, reactive wind slabs will be found on a variety of aspects and elevations due to terrain effects and the variable wind directions.

Cold temperatures are encouraging surface faceting of the upper snowpack. The late January interface is down 30-70 cm, this consists of surface hoar in sheltered locations, a crust on solar features, and facets and stiff wind affected snow at upper elevations. Below treeline, 10-30 cm of snow sits above isolated pockets of surface hoar and a crust that is more prominent on solar aspects. 

The mid-pack seems to be well settled. Deep persistent layers appear to have mostly become unreactive, with the exception of the Bear Pass area and the far reaches south of Kitimat. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Wind Slabs

An icon showing Wind Slabs

Outflow winds have been redistributing loose snow, building reactive slabs and reverse loading features. Avalanches will be most likely in wind loaded areas where the snow feels stiff or punchy. Note that in some places avalanche hazard may be elevated where winds have penetrated into unexpected places even at lower elevations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Persistent Slabs

An icon showing Persistent Slabs

30-70 cm sits above a buried weak interface that consists of surface hoar, facets, and/ or a crust. As the snow above this layer becomes more consolidated, the likelihood of avalanches may increase. 

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Feb 12th, 2021 4:00PM