Avalanche Forecast
Issued: Feb 15th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
shorton,
Avalanche Canada
Travel cautiously - the snowpack is suspect and avalanches are possible in a wide variety of terrain. Read more about managing these conditions in this forecaster blog.
Summary
Confidence
Moderate - A small change in the upper snowpack could dramatically change avalanche conditions.
Weather Forecast
A weak system crosses the region on Tuesday bring relatively warmer temperatures and some light flurries.
MONDAY NIGHT: Light flurries with 2-5 cm of snow in northern parts of the region, moderate northwest wind, treeline temperatures around -12 C.
TUESDAY: Clearing skies in the north with 2-5 cm of snow in the south, moderate northwest wind, treeline temperatures around -10 C.
WEDNESDAY: Sunny with a few clouds, light to moderate northwest wind, treeline temperatures around -8 C.
THURSDAY: Mostly cloudy, strong south wind, treeline temperatures around -6 C.
Avalanche Summary
There were a few reports of human triggered avalanches over the weekend including some small (size 1.5) sled triggered slab avalanches near Renshaw (MIN report) and some small dry loose avalanches in northern parts of the region where the persistent weak layer is shallowly buried. Prior to the cold snap, during the first week of February, there were numerous small human triggered avalanches on the same problematic persistent weak layer as well as some large natural avalanches. There are some great visuals of that activity in this MIN.Â
Snowpack Summary
It's time to monitor subtle changes in the upper snowpack as we leave a prolonged cold snap. A dusting of new snow and northwest wind could make upper elevation wind slabs more reactive, while warming temperatures could promote more reactive slabs above the widespread persistent surface hoar layer. This layer is already 40 cm deep around Torpy and McBride, but only 15-25 cm deep further north. Reports suggest this layer is most prevalent around treeline elevations, but likely reaches into the alpine and down into the trees too. It may sit above a crust below 1600 m. There are presently no deeper concerns in the snowpack.
Terrain and Travel
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Use ridges or ribs to avoid areas of wind loaded snow.
Problems
Persistent Slabs
Small changes to the upper snowpack could make persistent slabs easier to trigger. Currently, there is a widespread surface hoar layer buried 15 to 40 cm deep across the region. While there has been limited avalanche activity on this layer over the past week, cold weather has preserved this layer and it could re-emerge as a serious problem with additional loading or warming. This layer has been the most sensitive right at treeline, but it may extend up into the alpine, and/or down into the trees in some locations.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Wind Slabs
Watch for fresh wind slabs with new snow and moderate northwest wind forecast for Tuesday. Keep in mind recent wind has shifted directions and spread wind slabs across many terrain features and aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 17th, 2021 4:00PM
