Purcells

Wind slabs up to 50 cm deep may remain sensitive to human triggering in the alpine. Persistent slabs may roar back to life over the next few days as we go through a significant warm up. South facing slopes are especially suspect and are best avoided.

Moderate - Timing or intensity of solar radiation is uncertain on Monday

Monday, most of BC will receive partly cloudy conditions with a few lingering flurries in the Pucells. A warm system makes landfall Tuesday morning, which should open the door to rain and wet snow into the alpine on Tuesday and Wednesday.MONDAY: Scattered cloud cover, freezing level beginning around 1000 m rising to about 2000 m, light west wind at treeline, moderate to strong west/northwest wind at ridgetop, trace of precipitation possible. TUESDAY: Scattered cloud cover, freezing level beginning around 1500 m rising to about 2500 m, light southerly wind at treeline, strong southwest wind at ridgetop, trace of precipitation possible.WEDNESDAY: Scattered cloud cover, freezing level beginning around 2200 m lowering to about 1900 m, light to moderate southwest wind, 1 to 4 mm of precipitation possible.

On Saturday a skier got off line on an east/southeast facing alpine feature in the Invermere area and triggered a size 2.5 wind slab with a ski cut. They were able to ski out of the feature unharmed.A small human triggered wind slab avalanche was reported from the central portion of the region on an east facing slope at 2500 m on Friday.On Thursday a skier accidently triggered a large persistent slab avalanche on a south facing feature at 2600 m. The size 2 avalanche had a crown 60 cm in depth and failed on the mid March Persistent Weak Layer (PWL). Explosive control work produced cornice failures and storm slabs to size 2.5 on a variety of aspects in the alpine. Loose wet avalanches ran naturally to size 1.5 on steep south facing alpine slopes as well.

Recent wind and cold snow have formed wind slabs 10 to 50 cm in depth in the alpine that sit on a mix of crusts and surface hoar. Test profiles show resistent planar failures at this interface. In wind sheltered terrain Saturday's new snow rests on a surface crust that exists on all aspects aside from true north below 2000 m. This crust extends up to around 2400 m on south facing slopes. On north facing slopes above 2000 m, temperatures have remained cold and the snowpack is still quite "winter-like." The mid-March Persistent Weak Layer (PWL) is now 40 to 90 cm below the surface. This layer is composed of a crust on all aspects at low elevations. At upper elevations the layer presents as a crust on solar aspects (south and west) and buried surface hoar on polar aspects (north and east). The likelihood of triggering a deeper persistent slab avalanche is steadily decreasing but the consequence of doing so remains high. Solar aspects are expected to be the most suspect as the freezing level begins to rise over the next few days.Deeper persistent weak layers from January and December are still being reported by professional observers, but are generally considered dormant.