Human triggering of the new surface slab remains possible.
Use extra caution if you transition into wind affected terrain.
Up to 50cm of snow and strong wind gusts formed a surface slab on Wed/ Thurs. Although the colder temperatures have taken some energy out of this layer, careful evaluation of slab properties as you travel remains prudent.
Two persistent weak layers are buried down ~ 130 and 170 cm. Last weekends storm triggered these layers causing large, destructive avalanches. Use caution in thin snowpack areas that are not typically skied, and limit exposure to open paths that have not recently produced large avalanches.
Natural avalanches up to size 3 were observed along the highway corridor Thursday morning. These avalanches mostly failed in the recent storm snow, primarily in the steep terrain east of Rogers Pass.
Effective artillery control on Sunday produced widespread avalanches size 2-4.
For information on how to deal with persistent slab problems, see the Avalanche Canada blog post. Avalanches are happening less often, but when they do occur, the consequences are very serious.
In the Alpine and at Treeline, 30-80cm of storm snow has fallen since Mar 8. Moderate to strong southerly winds have loaded lee features in exposed terrain.
Below treeline, 20-30 cm of storm snow covers the Mar 8 rain crust, which is present up to ~1800m.
The Feb 9 and Jan 26 surface hoar (SH) layers are now buried 110-170cm deep. The Jan 26th layer is a crust with either surface hoar (up to 40mm in some places!) or facets on top of it.
Lingering instability brings mixed skies over the weekend. Early next week, a warm, wet airmass moves in.
Tonight Clear periods. Alpine low -13°C. Wind NW-15km/h. Freezing level (FZL) at valley bottom.
Sat Cloud/Sun/Flurries, Trace snow. High -13°C. Wind NW 15-35km/h. FZL 500m.
Sun Cloud/Sun/Flurries, Trace snow. Alp High -12°C. Wind: SW 25km/h. FZL 600m.
Mon Snow, 19cm. High -4°C, FZL 1200m. Wind SW-30 km/h
