Avalanche Forecast

Good

A strong northwesterly flow prevails as an upper ridge establishes itself offshore. Winds will be the most important feature to watch over the next 24 hours. No precip in the forecast for the next 72 hours.Saturday: Freezing Level: Valley Bottom; Precip: Nil; Wind: Mod NW, Strong at ridgetop. Sunday: Freezing Level: Valley Bottom; Precip: Nil; Wind: Light Variable, Mod NW at ridgetop.Monday: Freezing Level: Valley Bottom, potential for a slight temperature inversion at ridgetop; Precip: Nil; Wind: Light Variable, Strong W at ridgetop.

Both natural and human triggered avalanches were running to size 2 on all aspects and elevations Thursday. I suspect natural activity and size ramped up Thursday night into early Friday morning. Check back tomorrow for more details. As a general trend, the size and severity of avalanches has been greater in the north of the region where there has been more snow.

Thursdays storm delivered 20 - 50 cm of new snow bringing the average regional depth to 160 - 240cm.This new snow lies on top of old wind slabs, a thin melt freeze crust below 2100m and numerous weak layers. Down 50 -100cm is the mid December layer comprised of surface hoar, stallars and/or a crust. Around 80 -140cm down is the early December surface hoar, faceted snow and/or crust.There are two deeper layers of note. The late-November persistent weak layer consists of a sun crust on steep south facing slopes and surface hoar in sheltered areas and is now buried 90-160cm below the surface. The October deep persistent weak layer consists of a layer of facets sitting on a crust at the base of the snowpack. This layer is predominantly found on northerly aspects at treeline and in the alpine. The depth of both these layers makes directly triggering an avalanche on them unlikely (maybe a heavy load on a thin spot in steep terrain). Their presence could, however, increase the size of a potential avalanche through step-down.