Regions
Northwest Inland.
New snow and strong winds will elevate the hazard at treeline and above.
Confidence
Fair - Due to the number and quality of field observations
Weather Forecast
A Pacific low will deliver another round of moderate snowfall beginning today and continuing into next weekend. This event should bring around 30mm of precipitation, not all of which will arrive as snow ! Strong southwesterly winds will accompany the storm. Freezing levels will stay around the 1500M mark through Thursday then rise to almost 2000m on Friday before returning to more seasonal norms (valley bottom) Saturday afternoon.
Avalanche Summary
One report from yesterday of a size 2.5 natural that occurred on an East aspect around 2000m. As well, we received a report of a size 2 skier triggered avalanche on Hudsons Bay Mtn. with skier involvement and injuries. Local skiers have also reported natural activity on solar aspects. Both of these avalanches were wind slabs on old surfaces.
Snowpack Summary
Incoming precipitation will add load to the already reactive wind slabs in exposed lee terrain at treeline and in the alpine. Snow and winds from earlier in the week have added size and destructive potential to the developing wind slab problem. There are a variety of interfaces including old wind slabs, hard crusts, surface hoar, and/or surface facets buried below the recent storm snow. At the base of the snowpack, weak facets may be found and could possibly be triggered with a big enough load such as a cornice failure. Cornices are now getting to be large and potentially unstable. Solar aspects are also a concern, especially in the afternoon.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.