Avalanche Forecast

Issued: Jan 11th, 2021 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 Persistent Slabs.

Avalanche Canada ahanna, Avalanche Canada

Email

A bit of new snow and wind are likely forming fresh wind slabs at upper elevations. Watch for them to be reactive in leeward terrain features.

Summary

Confidence

Moderate - Uncertainty is due to the track & intensity of the incoming weather system.

Weather Forecast

Monday night: Flurries, trace, strong south wind, freezing level 1200 m.

Tuesday: Snow, 5-10 cm, strong south wind, alpine high -5, freezing level 1500 m.

Wednesday: Snow overnight then clearing, 5-10 cm, moderate west wind, alpine high -9, freezing level 1000 m.

Thursday: Sunny, light southwest wind, alpine high -9, freezing level 500 m with a weak inversion setting up.

Avalanche Summary

We have had a few recent reports of natural cornice falls and wind slab avalanches size 1-2 out of steep alpine terrain on north to east aspects.

Field observations in this region are limited. If you get out, please consider submitting your observations to the Mountain Information Network. 

Snowpack Summary

Small amounts of new snow fall on severely wind affected surfaces, surface hoar in wind sheltered areas and a thin crust on solar aspects. Strong winds are likely redistributing new snow into wind slabs and growing cornices. 

A couple of persistent weak layers exist in the upper to mid snowpack, down 20-60 cm and 70-100 cm. The distribution of these layers are variable, the upper layer spotty at treeline and below and the lower layer can present as surface hoar and/or a crust. It has been reported as most prevalent in areas near Valemount. Avalanche activity on these layers have dwindled since the storm and snowpack tests results have been moderate to hard planar, but still showing some propagation.

There is a prominent crust near the base of the snowpack. This crust likely has weak facets above and/or below it. There have been no recent avalanches reported on this layer, but would be most likely to trigger in steep, shallow, rocky terrain, where the snowpack transitions from thin to thick over a short distance.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Wind slabs are most reactive during their formation.
  • Dial back your terrain choices if you are seeing more than 20 cm of new snow.

Problems

Wind Slabs

An icon showing Wind Slabs

Light snowfall with strong winds are likely forming fresh wind slabs in leeward terrain features at upper elevations.

Cornices have also been growing. A cornice fall is a large load that can trigger avalanches on the slope below.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Persistent Slabs

An icon showing Persistent Slabs

A couple of weak layers exist in the mid snowpack, buried 20-60 cm and 70-100 cm below the surface. They are highly variable in form and distribution and have not been associated with avalanche activity in recent days. Incoming snowfall in the forecast for this week will add additional load to these layers and may shed some light on whether they will remain a concern.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Unlikely

Expected Size

2 - 3

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