Human triggered storm slabs are likely. Use extra caution in steep, wind effected terrain.
The persistent slab problem is still lurking in start zones that haven't avalanched on these weak layers.
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 snowpacks that are not typically skied and limit exposure to large avalanche paths that have not recently produced large avalanches.
Up to 50cm of snow and strong wind gusts formed a reactive storm slab. Use extra caution in lee features and exposed terrain. Below 1800 m the storm slab sits on a rain crust, which will act as a firm bed surface.
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 cover 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.
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.
Cool temps and continued flurries, with broken skies into the weekend.
Tonight Flurries, 5cm. Alpine low -15°C. Freezing level(FZL) valley bottom. Winds W 20-35km/h.
Fri Sun and Cloud, Precip: Nil. Alp High -11°C. Wind Light to 20km/h. FZL 700m.
Sat Cloud/Sun/Flurries, Trace precip. Alp High -16°C. Wind NW 15-30km/h. FZL 700m.
Sun Cloud/Flurries, Trace precip. Alp High -13°C. Wind: SW 15. FZL valley bottom.
