Avalanche Forecast

Moderate - Timing, track, or intensity of incoming weather system is uncertain

THURSDAY: Cloudy with snowfall, accumulation 15 to 30 cm, light to moderate southwesterly winds, alpine temperature dropping to -14 C, freezing level below valley bottom.FRIDAY: Mostly sunny, light northerly winds, alpine temperature near -14 C, freezing level below valley bottom.SATURDAY: Mostly sunny, light northwesterly winds, alpine temperature near -12 C, freezing level below valley bottom.

No new avalanches were observed on Tuesday. There was further evidence of a natural avalanche cycle from Friday to Sunday. Many slabs were observed, which were expected to have released during the storm. This includes many wind, storm, and persistent slab avalanches, from small to large (size 1 to 3). The slabs were 30 to 200 cm deep, on all aspects, and most often at upper below treeline, treeline and alpine elevations. Many of the releases propagated far and were highly destructive, such as this one, highlighting the consequence if an avalanche is triggered.Looking forward, dangerous snowpack conditions will exist on Thursday with substantial amounts of new snowfall and strong winds. This trend will likely continue until a more stable weather pattern governs and we see a decrease in avalanche observations. All of our buried weak layers (described in the section below) continue to produce large destructive avalanches from natural and human triggers. Storm and wind slabs have the potential to step down to deeper weak layers, which could produce very large avalanches with high consequences.

Up to 70 cm of snow could accumulate with the storm by Thursday afternoon. This overlies 50-100 cm of storm snow from the past two weeks that has formed a slab that sits over an unstable snowpack. There are four active weak layers that we are monitoring:1) The first layer is buried around 70 to 100 cm and is formed of a crust and/or surface hoar layer that was buried in mid-January. The surface hoar is up to 10 mm in size, found at all elevation bands and has been very reactive on north through east aspects between 1900-2600 m.2) Deeper in the snowpack, the early-January persistent weak layer is found 60 to 120 cm below the surface. This layer was reported as the most active persistent weak layer during a recent natural avalanche cycle that took place in the region. It was also very reactive to recent explosives control.3) Another weak layer buried mid-December consists of a facet/surface hoar/crust combination, which is 100 to 180 cm deep. It has been most problematic at and below tree line.4) A crust/facet layer from late November is yet another layer that could reactive with additional load.