Avalanche Forecast

Fair - Timing or intensity of solar radiation is uncertain

An unstable air mass will bring mainly cloudy skies and light snow amounts through the weekend, with freezing levels remaining at or near the valley bottom. If the sun shines through, solar radiation will be intense. Friday: Snow amounts near 5 cm. Sunny periods may exist on East facing slopes in the morning. Ridgetop winds moderate from the SW. Alpine temperatures -5. Freezing levels near 1000 m. Saturday: Snow amounts near 5 cm. Cloudy-broken skies. Ridgetop winds light from the SW. Freezing levels at valley bottom. Sunday: Mainly dry conditions. Broken skies in the morning, sunny skies in the afternoon. Solar radiation may be intense. Freezing levels rising to 600m.

Thursday the Coquihalla saw a widespread natural wet avalanche cycle between 1400-1700 m. Most slides were point releases, entraining mass from the recent storm snow, up to size 2.5. A couple avalanches were slabs with crown depths down 50-60 cm. This cycle occurred on all aspects, with no step down releases on lower weak layers. On Wednesday natural sluffing from steep terrain, and skier triggered pockets at treeline and below were reported. I suspect more natural activity occurring in the alpine with the new snow and cranking SW winds. Last week, warming prompted a widespread natural cycle in the Coquihalla and skiers triggered very touchy persistent slabs at low elevations. An unnervingly large natural avalanche cycle occurred at the start of this month, with slabs up to size 4.5 propagating 2-3km along ridgelines and stepping down to the mid-February layers.

Strong winds and snow have created wind slabs and storm slabs which are likely to fail in steep terrain, and could overload persistent weak layers. Persistent weak layers are variable in distribution across the region. Crusts down 50 cm can be found on solar aspects exist in the Duffey Lake, Chilcotin, and Coquihalla areas. Previously, these crusts had a poor bond. Tests done on these crusts are showing moderate-hard results with sudden planar characteristics. With the additional stress of a new load, these crusts may act as a sliding layer. Below this down approx. 100-150 cm, sit the mid Feb surface hoar, facets and a crust. Recent testing produced whumpfs and sudden planar results in snowpack tests. It is still is a key concern for step-down avalanches in many parts of the region. It is especially prevalent on south-facing slopes above treeline, and all slopes below treeline. Very large avalanches are possible, which could be remote-triggered, triggered mid-slope, and/or propagate into low-angled terrain.