Watch for signs of fresh wind slabs, such as stiff or slabby snow or blowing snow at ridgetops. If you've been out in the mountain please share your obs on the Mountain Information Network (MIN).
Confidence
Moderate - Due to the number and quality of field observations
Weather Forecast
WEDNESDAY: Cloudy with isolated flurries, 40-60 km/h west winds, alpine temperatures around -12C.THURSDAY: 5-10 cm of new snow, 50-80 km/h southwest winds, alpine temperatures around -10C.FRIDAY: Mix of sun and cloud, 30-50 km/h northwest winds, alpine temperatures around -12C.
Avalanche Summary
On Tuesday, ski cutting produced a size 2 wind slab in the most recent storm snow. Natural loose dry avalanches up to size 1.5 have also been reported out of steep terrain the past few days.Fresh wind slabs will be the primary concern on Wednesday, as strong winds will dramatically redistribute the new low density snow. Larger avalanches releasing on deeper persistent weak layers remain possible to trigger, particularly in shallow or previously wind-affected terrain.
Snowpack Summary
5-10 cm of fresh low density snow is being redistributed by strong winds and likely forming touchy wind slabs in the lee of ridgetops. A variable interface that formed during the cold snap in early December can be found buried 30-50 cm deep. This interface consists of weak faceted (sugary) snow and preserved surface hoar in sheltered areas. The interface is likely most reactive in wind-affected terrain where it is covered by hard wind slabs. The snowpack is a generally weak and faceted below this interface, including another weak layer with surface hoar or facets that was buried in early December. 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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.