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Avalanche Forecast

Dec 14th, 2020–Dec 15th, 2020
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
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
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: North Rockies.

Expect wind slabs to develop in exposed areas, especially on Wednesday as we see some new snow and strong winds.

Confidence

Moderate - Confidence is due to a stable weather pattern with little change expected. Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.

Weather Forecast

MONDAY NIGHT: Dry or light flurries. Treeline temperatures around -10 C. Moderate ridgetop winds southwesterly around 40 km/h.

TUESDAY: Flurries. Treeline temperatures around -8 C. Moderate ridgetop winds southwesterly around 40 km/h.

WEDNESDAY: Around 10 cm new snow. Treeline temperatures around -5 C. Strong ridgetop winds southwesterly 50-70 km/h.

THURSDAY: Around 10 cm new snow. Treeline temperatures around -10 C. Light northwesterly winds.

Avalanche Summary

No recent slab avalanche have been observed in this regions.

Snowpack Summary

Snow depths are approximately 150 cm around Pine Pass, Torpy and McBride and around 100 cm in the northeast around Tumbler Ridge. 

The alpine is heavily wind-affected and lower elevations are capped by a hard crust up to around 1300 to 1600 m. Sheltered areas at treeline may still have 5 to 20 cm of soft snow on the surface. 

A widespread crust layer that may have sugary faceted grains above it can be found at the bottom of the snowpack. Uncertainty remains about if and where this layer is a problem. Recent observations from the McBride area suggest the snow is well-bonded to this crust. Observations from around Tumbler ridge suggest ongoing concern for this layer in this zone. I suspect the layer to be potentially reactive in northern parts of the region, such as Pine Pass, but do not have observations to back this up. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Avalanche Problems

Wind Slabs

Triggering wind slab avalanches remains possible at higher elevations, especially on freshly wind-loaded terrain features. New wind slabs are likely to form during periods of strong wind on Monday.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Deep Persistent Slabs

We are uncertain about where the early-November crust has weak faceted grains above it, and if this layer remains as a problem. Our limited information suggests this problem is more likely found around Pine Pass and the eastern slopes of the Rockies. Given our lack of field observations, the prudent choice is to approach any big open slope with caution, especially slopes that are rocky and have variable snowpack depths.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 2 - 3