Avalanche Forecast
Issued: Dec 1st, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet and Wind Slabs.
ghelgeson,
Avalanche Canada
It's expected to be very warm and sunny Wednesday, alpine temperatures could be as warm as +6 C. The snowpack doesn't like rapid changes like this. Cornice failures and even natural avalanches are possible as we head into the warm spell.
Summary
Confidence
Low - Uncertainty is due to the limited number of field observations.
Weather Forecast
An inversion dominates the forecast period bringing warm sunny conditions to the alpine while the valleys remain cool.
TUESDAY NIGHT: Freezing level at valley bottom with an inversion starting to set up that brings above freezing temperatures between about 2000 and 3500 m, light variable wind, no precipitation expected.
WEDNESDAY: Clear sunny skies, below freezing in the valley with an inversion in place, above freezing temperatures between about 2000 and 3500 m, light variable wind, no precipitation expected.
THURSDAY: Clear sunny skies, below freezing in the valley with an inversion in place, above freezing temperatures between about 2000 and 3500 m, light to moderate west/southwest wind, no precipitation expected.
FRIDAY: Clear sunny skies, no inversion expected, freezing level holding near valley bottom, light variable wind, no precipitation expected.
Avalanche Summary
Warm temperatures and direct sunshine are coming our way. Natural avalanche activity is possible as things start to warm up.
Observations are limited right now, but there have been no reports of recent avalanches. We appreciate the recent reports submitted to the Mountain Information Network. Keep them coming!
Snowpack Summary
Wind slabs have formed on open leeward terrain as last week's 10 to 15 cm of snow was redistributed and formed into more cohesive slabs. Snow surfaces are scoured on windward slopes.Â
Surface snow conditions may change with forecast sunshine and warmer temperatures up high this week. Surface snow may be moist and reactive on sunny slopes.
Snowpack depths are variable with reports of 50 to 100 cm in terrain that hasn't been scoured by the wind. There are some reports of a hard crust buried about 30 cm below the surface, which could be a bed surface for wind slab avalanches. The early November crust has been spotted down 65 cm in the region. This layer could become a bigger concern when it gets buried deeper.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Extra caution for areas experiencing rapidly warming temperatures for the first time.
- Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
Problems
Loose Wet
It's anticipated that Wednesday will be unseasonably warm and sunny. Loose wet avalanche activity is expected to be widespread.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Watch for old wind slabs in the alpine, and open "alpine like" features at treeline. These slabs may be poorly bonded to underlying crust and surface hoar layers, although the distribution of these layers is uncertain. These old wind slabs may become reactive with afternoon sun, especially on steeper terrain features and solar aspects.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 2nd, 2020 4:00PM
