Avalanche Forecast

Wednesday night: Mostly clear, moderate south wind, freezing level rising to 2200 m. 

Thursday: Sunny, light to moderate southwest wind, freezing level rising to 2300 m.

Friday: Increasing cloud, moderate to strong southwest wind, freezing level near 2100 m.

Saturday: Mostly cloudy, 5-10 cm of snow, moderate southwest wind, freezing level near 1500 m.

Numerous large (size 2) natural wet loose avalanches released naturally on south-facing aspects between 1700-2000 m on Wednesday.

Over the weekend, there were a few natural and skier triggered wind slabs size 1.5. On Saturday, large explosive loads produced very large (size 2-3) results at Kootenay Pass. In thin snowpack areas on solar aspects, a few of these large avalanches are suspected to have stepped down to the January layer described in the snowpack summary.

Above freezing temperatures are forecast to reach 2300 m on Thursday with added intensity from strong sun. This rapid warm-up is expected to initiate wet loose avalanche activity and destabilize cornices. Watch for pinwheels and roller balls, as they are a clear indication of this problem. You can avoid them by staying off steep slopes when the snow becomes wet or slushy. Read more about the effects of warming on the snowpack in the Forecaster Blog. 

At upper elevations, 20-40 cm of recent snow has seen significant wind effect, with reports of cross-loaded features and scouring on exposed windward aspects. At treeline and below, the recent snow may sit over a layer of small surface hoar crystals in isolated areas.

A persistent layer buried 80-150 cm deep is composed of a combination of surface hoar, crusts, and facets that formed on the surface in late January. The problem seems to be most pronounced in thin snowpack areas on solar aspects. Recently, large explosive loads have been required to trigger an avalanche on this layer, but a rapid rise in temperature may have the potential to initiate these large avalanches. 

As described in this MIN report, shallow snowpack areas in the east of the region may harbor a faceted basal snowpack. This structure can typically be managed by avoiding shallow rocky areas where the snowpack transitions from thick to thin. This is another layer that could be susceptible to shock from the warm temperatures this week. Extra caution should be exercised in these types of snowpacks.

• Back off slopes as the surface becomes moist or wet with rising temperatures.
• Extra caution for areas experiencing rapidly warming temperatures for the first time.
• A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
• If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.