Avalanche Forecast
Issued: Mar 14th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
ldreier,
Avalanche Canada
Fresh wind slabs were formed by moderate to strong northeast wind at upper elevations and might be reactive to human triggers. The sun is strong at this time of year and can weaken the snowpack. Be especially cautious underneath sun exposed steep slopes and around rock outcrops.
Summary
Confidence
Weather Forecast
Saturday night: Clear, moderate northeast wind, alpine high temperature -22 C, freezing level at valley bottom.
Sunday: Sunny, light northeast wind, alpine high temperature -15 C, freezing level at 600 m.
Monday: Sunny, light north wind, alpine high temperature -10 C, freezing level at 1000 m.
Tuesday: Mostly sunny, light northerly wind, alpine high temperature -7 C, freezing level 1000 m.
Avalanche Summary
A natural avalanche cycle occurred most likely during the storm on Tuesday with avalanches up to size 3. No new avalanche activity was reported in the last couple days.
Snowpack Summary
Moderate to strong northeast wind has redistributed snow and formed wind slabs at all elevations. The snow surface varies from soft low density snow to wind pressed at wind exposed terrain.
A weak layer of surface hoar may be found 50-100 cm deep. Reports indicate that this layer may be absent in the northern tip of the region (see this MIN from Sugarbowl). However, observers have identified the layer in snow profiles from Barkerville to Valemount (see this MIN from Mt Greenbury, this MIN from the Trophy Mountains, and this MIN from Allan Creek). Sheltered north, northeast, and east facing slopes near treeline are the most suspect.
This persistent slab problem has transitioned into a low probability/high consequence scenario. If triggered, avalanches will be large and getting caught could have serious consequences. Managing this problem requires a patient and diligent mindset, implemented by avoiding suspect slopes and maintaining conservative terrain margins.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
Problems
Wind Slabs
Moderate to strong northeast wind formed wind slabs in the alpine and at treeline which might be reactive to human triggering. Exposure to the sun might increase the reactivity of wind slabs especially on steep solar aspects.
Aspects: East, South East, South, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of surface hoar is buried 50-100 cm deep. Even though avalanche reports decreased over the past week it might still possible to human-trigger. Past observations were concentrated to north, northeast, and east aspects near treeline. This problem has been observed in all but the northern tip of the region, where there is uncertainty around the distribution of this layer.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 15th, 2020 5:00PM
