Watch for new and recent wind slabs in unusual places after rapid shifts between northwest and southwest winds. Surface instabilities aside, the basal snowpack continues to demand thoughtful terrain selection to avoid triggering a very large avalanche. Keep up the safe group management decisions and avoiding shallow rocky start zones.
Elevated northwest winds have likely formed wind slabs on leeward slopes along ridgecrests at higher elevations. Expect any you encounter to remain reactive to human triggering on Saturday.
Faceted grains make up the basal snowpack and are gaining strength very slowly. Where supportive to riders, a melt-freeze crust may be providing a bridging effect, making it more difficult to trigger deeper layers. Any avalanche triggered this deep will likely be large and destructive.
Explosives control in the Fernie area yielded storm slabs to size 2 (large) on Thursday, with depths of up to 15 cm and propagations up to 50 m wide. This is a good indication of surface instabilities you may find lingering in in leeward terrain features near ridgecrests on Saturday.
On Tuesday and Wednesday, more human-triggered wind slabs up to size 1 were reported at treeline and above.
Roughly 10 cm of recent snow has been getting moved into small wind slabs in exposed areas and otherwise blending into older wind-affected surfaces above 1800-2000 m and settling on a crust below this elevation.
A crust/facet layer (2-15 cm thick at TL elevation) is down 50-90 cm. Where it's thickest, it caps the settled and consolidated mid-snowpack.
Another crust/facet layer is down 70-150 cm. Below this crust, the basal snowpack is weak and faceted.
Friday night
Mainly cloudy. Light southwest or northwest winds, more northerly with elevation.
Saturday
Increasing cloud with isolated flurries, increasing overnight. Moderate to strong southwest winds, increasing over the day. Treeline high temperatures around -6.
SundayCloudy with easing flurries and a variable trace to 10 cm of new snow, including overnight amounts. Light to moderate northwest winds. Treeline high temperatures around -6.
MondayCloudy with scattered flurries bringing less than 5 cm of new snow. Light to moderate southwest winds. Treeline high temperatures around -6.
More details can be found in the Mountain Weather Forecast.
