Wind Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 1–2
Moderate to strong winds have built wind slabs at alpine and treeline elevations. This problem will increase with forecasted snow and wind on Thursday and Friday.
Two important headlines:
1) The surface hoar problem has become very significant in Kootenay and probably in Yoho too. Avoid steep terrain at and below treeline.
2) A significant storm is coming, resulting in increased hazard on Thursday and Friday. Conservative terrain choices are required.
Moderate to strong winds have built wind slabs at alpine and treeline elevations. This problem will increase with forecasted snow and wind on Thursday and Friday.
A 30-40 cm slab over the Jan. 24th surface hoar layer is very touchy and will almost certainly release if you ski through any steep slope between 1600 and 2200 m in this area. We expect an avalanche cycle on this layer with the forecasted new snow.
No recent reports from this area.
At lower elevations, we continue to receive reports of increased reactivity of the surface hoar problem. This is very significant and getting worse. On Tuesday, our field team observed a size 2 avalanche in the Simpson area that ran 300 m through thick forest. Over the past week, there have been several skier-triggered avalanches on this problem to size 1.5.
Forecasted wind and new snow on Thursday and Friday will create fresh wind slabs and storm slabs at all elevations. The Jan 24 layer (surface hoar/crust) is down 30-40 cm at treeline and has been super touchy in Yoho and Kootenay. With the additional load of the forecasted snow, we are expecting to see a natural cycle on this layer. Starting Thursday afternoon, the snowpack's stability will deteriorate rapidly as the storm arrives.
A significant storm is expected to hit the forecast region starting on Thursday and cresting Thursday night and Friday. Forecast amounts vary, but amounts could be in the range of 25-35 in the north regions and 15-20 in the southern regions. The one factor that is consistent is the wind. Forecasted winds for all regions is strong from the west. With the forecasted wind and snow we expect to see an avalanche cycle.