The persistent slab problem is complex and unpredictable.
Start with conservative terrain and gather information before committing to larger slopes.
Watch out for wind-loaded features, especially near ridge crests, rollovers, and in steep terrain. If triggered, wind slabs may step down to deeper layers, resulting in larger avalanches.
Weak layers remain a concern, especially in north-facing terrain and where snowpack depth is variable. Avoid steep and shallow rocky features at upper elevations. These layers have caused recent very large avalanches in the region.
A widespread avalanche cycle occurred in the region over the past few days, with avalanches up to size 3.5 (very large) reported. In many cases, storm slabs or wet avalanches stepped down to deeper persistent weak layers.
With temperatures falling, natural avalanche activity is expected to taper off, but human-triggered avalanches remain possible to likely at upper elevations.
Recent rain and warming created a moist/wet upper snowpack 40 to 50 cm deep, right to ridgetops. As temperatures cooled, a crust formed at upper elevations. 10 to 20 cm of new snow may now cover this crust with moist snow below. Isolated wind slabs may exist at upper elevations on wind-loaded slopes. The early March weak layer of facets, or surface hoar on a crust, is now down 60 to 130 cm. Very large avalanches (up to size 3.5) were reported on this layer this past week. Weak layers formed in mid-February and late-January are now buried 140 to 200 cm deep.
Friday Night
Cloudy, with 1 to 5 cm of snow above 1500 m / possible light rain below. 15 to 30 km/h southwest ridgetop winds. Treeline temperature -3 °C. Freezing level 1700 m, dropping to 1000 m.
Saturday
Cloudy with 0 to 10 cm of snow above 1000 m, possible rain below. 15 to 30 km/h south ridgetop winds. Treeline temperature 0 °C. Freezing level rising to 1700 m.
Sunday
Sunny. 10 km/h southeast ridgetop winds. Treeline temperature +2 °C. Freezing level rising to 2000 m.
Monday
Mostly cloudy with 0 to 5 cm of snow above 1500 m, possible rain below. 10 to 20 km/h variable ridgetop winds. Treeline temperature 0 °C. Freezing level rising to 1700 m.
More details can be found in the Mountain Weather Forecast.
