Avalanche Forecast
Issued: Feb 9th, 2018 4:46PM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
High -
Weather Forecast
Saturday: Mainly sunny with some valley cloud due to a temperature inversion. Light to moderate southwest winds, strong at high elevations. Alpine high temperatures to -7 with cooler temperatures at lower elevations.Sunday: A mix of sun and cloud. Light north winds. Alpine high temperatures around -12 and falling as the temperature inversion breaks down overnight.Monday: Mainly sunny with some valley cloud as another temperature inversion establishes. Light southwest winds, increasing overnight. Alpine high temperatures around -8, cooler at lower elevations.
Avalanche Summary
Reports from Thursday included observations of numerous storm slabs releasing from size 1-2.5 throughout the region. Avalanches were observed on all aspects and elevations. Two very large persistent slab avalanches (size 2.5 and 3.5) were observed, with crown fractures from 150-200 cm deep. One of these ran for over a kilometre and destroyed mature timber along its edges.A MIN report from Wednesday shows an approximate size 1.5 skier triggered avalanche within the city limits of Prince George, illustrating that avalanche terrain is not confined to the backcountry.Monday's observations showed further evidence of a natural avalanche cycle from Friday to Sunday. Many wind, storm, and persistent slab avalanches from size 1 to 3 were reported. The slabs were 30 to 200 cm deep, on all aspects, and most elevations. Many of the releases propagated far and were highly destructive.Looking forward, it will be essential to maintain elevated caution as danger ratings shift into the CONSIDERABLE range. As the likelihood of triggering avalanches diminishes, the consequences and destructive potential of avalanches will remain dangerously high.
Snowpack Summary
Recent accumulations of 30-40 cm have formed reactive new storm slabs on the surface throughout the region. This adds to 50-100 cm of storm snow from the past two weeks that has settled into a thick slab over an unstable snowpack. There are four active weak layers that we are monitoring:1) Around 80 to 140 cm deep, you'll find a layer of crust and/or surface hoar that was buried in mid-January. The surface hoar is found at all elevations and has been especially reactive on north through east aspects between 1900-2600 m. 2) Deeper in the snowpack, the early-January surface hoar layer is found 90 to 160 cm below the surface. 3) Another weak layer buried mid-December consists of a facet/surface hoar/crust combination, which is 120 to 200 cm deep. It has been most problematic at and below tree line.4) A crust/facet layer from late November is yet another weak layer lingering near the base of the snowpack.Each of the above layers have maintained a trend of producing notable avalanche activity and concerning snowpack test results for the past couple of weeks. The wide distribution and ongoing reactivity of these layers suggests that choosing simple terrain is the best avoidance strategy.
Problems
Storm Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 10th, 2018 2:00PM