Light flurries and elevated winds should keep wind slabs fresh and reactive to skier triggering on Saturday. Seek out sheltered areas and remember that bigger wind slabs may step down to deeper snowpack weaknesses to create large, destructive avalanches.
Southwest winds are redistributing storm snow into deep pockets at higher elevations. Slabs will likely be the deepest and most reactive on north and east aspects at treeline and above.
Keep in mind that wind slabs have the potential to step down to deeper weak layers, resulting in large and consequential avalanches.
Numerous problematic weak layers exist in the top meter of the snowpack. Recent large persistent slab avalanche observations are strong evidence that these layers are still an active concern in this region. These layers have been most prevalent in the southern part of the region.
A layer of large and weak facets sits near the base of the snowpack. This layer continues to produce very large avalanches that can travel far. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain, or by triggering a smaller avalanche that could step down to this layer. Your best defence is to stay diligent in choosing low-consequence terrain away from overhead exposure. See more on the potential of triggering deeper weak layers in our latest Forecasters' Blog.
Reports from Thursday included more observations of the natural cycle described below, in addition to several size 1 (small) to size 2 (large) skier-triggered slabs. Size 1's were up to about 20 cm -deep wind slabs while the lone new size 2 north of Trout Lake failed on a 75 cm-deep freezing rain crust buried in early January.
With clearer weather on Wednesday, a widespread avalanche cycle from within the storm was observed across the region. Several persistent slab avalanches were reported between 2200 and 2400 meters on all aspects. Notable was a size 2 vehicle remote persistent slab avalanche, triggered from 70 m away on a northwest aspect. Several deep persistent slabs were reported to size 4 throughout the Selkirks and Purcells. Numerous wind slab and storm slab avalanches were reported to size 3 on all aspects at treeline and above.
On Tuesday, a few size 1 skier accidentals storm slab avalanches were reported 20-40 cm deep. Numerous natural avalanches were reported primarily on north and east aspects where storm snow and wind created deep pockets of slab. Explosive control produced numerous storm slab results to size 3.5.
Southwest winds have been redistributing storm snow into 20-30 cm soft slabs in exposed alpine and treeline areas. 40-90 cm of storm snow from the week sits above wind-affected surfaces and a crust that extends up to 1800 m in the northern part of the region and up to 2000 m further south. Small facets may be found above the crust.
Deeper in the snowpack two layers of surface hoar which formed in early January are 60 to 120 cm deep. These weak layers are still on our radar, although snowpack tests are indicating they may be strengthening.
Large and weak facets from November are near the base of the snowpack, which continue to produce very large avalanches in the region.
Friday night
Cloudy with isolated flurries and up to 5 cm of new snow. Light to moderate southwest winds, strong in the alpine.
Saturday
Cloudy with isolated flurries and and about 5 cm of new snow from the overnight period. Light to moderate southwest winds. Treeline high temperatures around -4 with freezing levels rising to 1300 metres.
Sunday
Increasing cloud and flurries bringing 5-10 cm of new snow by end of day, continuing overnight. Light to moderate southwest winds, becoming strong or even extreme in the alpine. Treeline high temperatures around -2 with freezing levels to 1300 metres again.
Monday
Cloudy with another 5-10 cm of new snow from the overnight period. Light southwest winds. Treeline high temperatures around -5.
More details can be found in the Mountain Weather Forecast.
