Wind slabs and persistent slabs are trending smaller and less likely to trigger, but conditions still demand assessment of suspect features in wind affected areas and around sheltered openings at lower elevations.
Summary
Confidence
Moderate -
Weather Forecast
Monday night: Clear. Light east winds.Tuesday: Sunny with cloud increasing over the day. Light east or southeast winds. Alpine high temperatures around -9.Wednesday: Mainly cloudy with isolated flurries and a trace of new snow, increasing a bit overnight. Light southeast winds. Alpine high temperatures around -7.Thursday: Cloudy with scattered flurries bringing around 5 cm of new snow, with new snow totals of up to 10 cm. Flurries easing overnight. Light to moderate southwest winds. Alpine high temperatures around -9
Avalanche Summary
Observations from the past few days have shown size 1-2 wind slabs releasing with skier traffic on a range of aspects at ridgetop, most recently on southwest aspects (lee of recent northeast winds). A few storm slabs were reported in the south of the region where up to 30 cm of snow fell at the end of the week. Small (size 1-1.5) loose dry avalanches have also been observed releasing naturally from steeper, sun exposed slopes. Persistent slab avalanche activity on the mid-January weak layer has slowed down, but not stopped. This layer has evolved a lower likelihood avalanche problem focused at treeline and below. Check out the great photos from a
MIN dated from February 23 for a higher consequence example of this layer's potential. Take note of the low angle terrain, treeline elevation, and the light load of a single ski track that triggered this avalanche.
Snowpack Summary
Up to 20 cm of recent snow exists in a few areas in the south of the region from convective snowfall at the end of last week. This snow likely overlies sun crust on sun-exposed aspects. Below any new snow, strong ridge-top winds (most recently from the northeast) have created wind slabs on all aspects at upper elevations. These wind slabs have shown prolonged reactivity because of the faceted (weak, sugary snow) they overlie. There are two prominent weak layers in the upper snowpack that were buried in mid and late January. They can be found between 40-90 cm below the surface. These layers consist of surface hoar (weak, feathery crystals) and may be associated with crusts on steeper, south facing slopes. These weak layers have been most prominent and most reactive at lower elevations - especially below treeline.The lower snowpack is generally considered to be strong, except for shallow, rocky areas where the cold temperatures continue to facet (weaken) the snowpack.
cgarritty,
Avalanche Canada
