New snow and strong winds on Monday will form new wind slabs in exposed terrain. Use extra caution in wind affected terrain and avoid freshly wind loaded features.
Confidence
Low - Timing, track, or intensity of incoming weather system is uncertain on Tuesday
Weather Forecast
Around 15 cm of snowfall is expected for Monday with strong alpine wind from the west and treeline temperatures around -10C. A break is expected Monday night before another pulse of precipitation arrives on Tuesday. Models are currently showing another 5-10 cm with strong alpine wind from the southwest and treeline temperatures around -5C. Dry and sunny conditions are currently forecast for Wednesday.
Avalanche Summary
On Friday and Saturday, ski cutting in the southeast of the region produced numerous size 1 wind slab avalanches in leeward terrain features. These were 5-15 cm thick. On Thursday, a natural size 2 wind slab occurred in the Corbin area. This occurred at 2000m elevation on a northeast aspect as a result of recently strong southwest winds. Check out the MIN post for more details and a photo. New snowfall and strong westerly winds are expected to result in new wind slab formation or add additional load to existing wind slabs which may still be lingering. Recent winds have mainly been from the southwest through northwest directions and wind slabs should be expected on opposite aspects in wind exposed terrain.
Snowpack Summary
The new snow buries a variable surface that developed over the last week of cold, dry, and windy conditions. This interface consists of scoured surfaces and wind slabs in wind exposed terrain, widespread faceting of the upper snowpack, and surface hoar up to 20 mm in sheltered areas. In sheltered areas, there may be a layer of surface hoar in the upper snowpack which was buried around December 10. The mid pack is generally well settled. The thick crust from mid-November is near the bottom of the snowpack and recent tests suggest that the crust is currently well bonded to the surrounding snow. Below treeline, the snowpack is very shallow and early season hazards such as stumps, rocks, and open creeks are still a major concern.
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.