Avalanche Forecast
Issued: Dec 9th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
shorton,
Avalanche Canada
Pay close attention to changing conditions as slab avalanches will become more likely with the incoming storm.
Summary
Confidence
Moderate - A small change in the upper snowpack could dramatically change avalanche conditions.
Weather Forecast
A frontal system will arrive on Friday night and bring strong wind and new snow.
THURSDAY NIGHT: Cloudy, no significant precipitation, moderate wind from the west, treeline temperatures around -10 C.
FRIDAY: Increasing cloud with afternoon flurries bringing up to 5 cm of snow, strong wind from the southwest with gusts to 60 km/h, treeline temperatures increase to -7 C.
SATURDAY: Snowing throughout the day with a total of 10-25 cm, strong wind from the south with gusts to 90 km/h, treeline temperatures around -5 C.
SUNDAY: Partly cloudy with scattered flurries and up to 10 cm of new snow, moderate wind from the southwest, treeline temperatures around -8 C.
Avalanche Summary
Reports from Wednesday highlight that slabs are becoming more reactive. There were several reports of natural size 2 avalanches in alpine terrain as well as several human triggered size 1 wind slabs around treeline. The most reactive slabs were on convex wind-affected slopes. Most avalanches were in the top 20-30 cm of snow.
We will likely see more widespread avalanche activity in all types of terrain with the incoming storm this weekend, but on Friday, the most likely avalanche activity will continue to be in wind-affected areas.
Snowpack Summary
30-60 cm of recent snow will begin settling above a variety of suspect layers over the next few days. The most widespread layer is a crust beneath this snow that formed during last week's atmospheric river. This crust extends into the alpine (as high as 2200 m), and there is potential for a poor bond to this crust. We are uncertain about how reactive the recent snow will be as it settles over the upcoming days. The snowpack structure is relatively simple beneath the crust, with treeline snow depths around 150-250 cm.
Terrain and Travel
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Avoid areas where the snow feels stiff and/or slabby.
- Closely monitor how the new snow is bonding to the crust.
- Be alert to conditions that change with elevation and wind exposure.
Problems
Wind Slabs
Recent weather has likely left unstable wind slabs at upper elevations, especially on the leeward side of ridges. Pay attention to the look and feel of the surface snow, as slab formation could also become more widespread. If slabs develop, they could be poorly bonded to the underlying crust.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 10th, 2021 4:00PM
