Avalanche Forecast

Good

Tuesday: Mainly sunny with valley cloud. Light southerly winds. Freezing level around 600m. Wednesday/Thursday: Cloud and flurries. Light south-west winds. Temperatures remain cool, except during sunny breaks, when some local solar warming may occur.

Many large natural and human-triggered avalanches have been reported each day since Wednesday. Natural activity (up to size 3.5) spiked following the heaviest snowfalls on Tuesday night and Friday night. Skiers have been triggering avalanches (mostly size 1-2.5) accidentally and remotely. These are running on storm snow instabilities or persistent weaknesses in the upper snowpack. There have been some lucky escapes. Conditions will remain ripe for human-triggering after the more obvious signs of instability (like new snowfall, wind-loading and natural activity) die down.

Recent storm snow totals of about 60-140cm sit above the Feb 16. surface hoar layer and the early Feb interface. The early Feb interface is a combination of weak layers: In most locations it marks a widespread surface hoar layer. On steep south- and west -facing aspects, a sun crust was also buried at the same time, meaning that most terrain in the region has a weak layer in the upper snowpack. Deep wind slabs exist on many aspects and cornices are large. Upper snowpack persistent weak layers are still very touchy, as evidenced by scores of remote and human-triggered avalanches over the past several days. Cornice fall and solar warming are my top current picks for further natural triggering of these weak layers, while human/machine-triggering remains likely on a variety of slopes.