Rapid loading, warm temperatures and strong wind are a recipe for HIGH danger. Avoid avalanche terrain and stay well back from runout zones.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
We'll see lingering flurries on Sunday as it cools down significantly. Clearing Monday onwards.SUNDAY: Broken skies with isolated flurries / moderate to strong west wind / Alpine temperature -8 / Freezing level 800mMONDAY: Increasing cloud in the afternoon and some scattered flurries / Light east wind / Alpine temperature -6 / Freezing level 1200mTUESDAY: Isolated flurries / Light to moderate southwest wind / Freezing level 1500m
Avalanche Summary
On Friday skiers triggered a Size 1.5 wind slab quite low down on a slope - strong winds had transported snow farther than expected. On Thursday a Size 2.5 natural slab avalanche on a west aspect took out trees. The sun came out in force and cornices were failing.
See here for this great MIN report.There was a widespread natural avalanche cycle to size 3 on all aspects and elevations from last Wednesday's storm in the areas south of Valemount. Expect the storm slabs to continue to be reactive at upper elevations, especially with more loading on Saturday.
Snowpack Summary
In the south of the region, heavy snow (25 cm in 10 hours) and strong winds (gusts over 60 Km/hr) started late Friday and continued through Saturday. Temperatures also warmed up significantly. The end result: Widespread storm slabs and wind slabs at treeline and above with significant cornice growth as well. All this new snow sits on older windslabs (or soft slabs) at treeline and above. Below 1800m, the new snow sits on a melt-freeze crust from last week's warm storm, and reports so far are that the new snow is bonding well to the old crust. Approximately 100-140 cm below the surface you may find the mid-February persistent weakness. Professionals in the region have warned that the load above this layer has reached a critical amount, particularly where it presents as a crust.Deep persistent weaknesses in the lower third of the snowpack still have the potential to react to human triggers or smaller slab avalanches, especially with the warming temperatures and/or intense sunshine early next week. New snow totals in the north (Wells, Sugar Bowl) have been half to one-third of those in the south and avalanche danger is likely one step lower.
mgrist,
Avalanche Canada
