Avalanche Forecast
Issued: Dec 27th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
ahanna,
Avalanche Canada
Hazard may be improving but keep in mind that potential size and consequences of human triggered avalanches remain high. Deep instabilities like this are difficult to assess from the surface, so let terrain selection be your solution.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
FRIDAY NIGHT: Mostly cloudy, alpine low -12 C, alpine wind moderate from the west.
SATURDAY: Mostly cloudy with isolated flurries, alpine high -7 C, alpine wind moderate from the west.
SUNDAY: Scattered cloud, alpine high -7 C, light variable wind.
MODAY: Scattered cloud, alpine high -7 C, alpine wind building to strong from the west.
Avalanche Summary
No new activity has been reported since Monday.
Last weekend, there were reports of numerous natural and explosive triggered avalanches up to size 2.5
Snowpack Summary
Moderate winds over the last couple of days are likely to have blown around some of the 40 to 70 cm from last weekend's storm, forming soft windslab in alpine lees. Anywhere from 40 to 100 cm of snow is now resting on a widespread layer of large, feathery, surface hoar which we're calling the "December 12th Surface Hoar." This layer was the culprit for the large natural avalanche cycle during and after last weekend's storm. Activity on this interface has likely tapered off, but there remains some uncertainty as to how quickly the snowpack is gaining strength.
A weak layer formed in late November is now buried around 1 m or more below the surface. This interface may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect.
Terrain and Travel
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Caution around convexities or sharp changes in terrain.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
Problems
Persistent Slabs
All of the old storm snow is slowly settling into a slab which rests on weak surface hoar 40 to 100 cm below the surface. Natural avalanche activity has waned, but human triggering may still be possible, especially in more challenging/complex terrain. This isn't the kind of avalanche problem you can necessarily feel under your skis, track or feet, it may be too deep for that. The answer lies in terrain selection.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
A bit of new snow and wind out of both the southwest and northwest Thursday and Friday is likely to form fresh wind slabs in exposed terrain features.
Aspects: North, North East, East, South East, South.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 28th, 2019 5:00PM
