Regions
Northwest Inland.
Weather Forecast
Tonight and Monday: An arctic ridge is building and is there to stay for a little while. Expect mainly sunny skies, moderate to strong NE winds, and cold temperatures (-18 C in the alpine). Tuesday: The ridge is gaining more strength spreading more dry and cold weather. Strong NE winds, partly cloudy skies, alpine temperatures around -20 C. Wednesday: More of the same. Mainly clear skies, cold temperatures but winds should diminish to lighter speeds from the N.
Avalanche Summary
Skier triggered slab avalanches size 1 in thin windslabs in the alpine were reported in the Northern part of the region. There was also report of a glide crack release size 2 on a NE aspect at treeline elevation.
Snowpack Summary
The 5-10 cm of recent snow has been redistributed by NE winds most likely creating pockets of relatively thin windslabs on immediate lee features in the alpine and at treeline. These windslabs or the light dry snow are sitting on weak surfaces like a widespread crust or on the late January surface hoar layer sheltered areas. At this time, there is not enough snow above this weak layer to create an avalanche danger. The deep persistent layer of weak facets continues to be a concern in shallow snowpack areas, however the re-frozen upper snowpack may make triggering less likely. At the surface of the snowpack, there is widespread growth of surface hoar and surface facetting that will continue with the forecasted clear and cold temperatures.
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.