South-facing slopes and areas with thin snowpacks are the most suspect for avalanche activity.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
WEDNESDAY: Cloudy, 20-30 km/h north winds, alpine temperatures around -18.THURSDAY: Cloudy with isolated flurries and trace accumulations, light west winds, alpine temperatures around -16.FRIDAY: Cloudy with isolated flurries, light southwest winds, alpine temperatures around -14.
Avalanche Summary
Reports from the region are limited to old size 2 wind slabs that occurred during the major wind event on New Years Day. The reports suggest wind loading occurred in open terrain at all elevations and aspects. Lingering wind slabs may remain reactive to human triggering on specific features, such as the immediately lee of ridges and sun-exposed slopes.
Snowpack Summary
Strong winds on Sunday had an extensive effect in exposed terrain at all elevations. Expect scouring, hard wind slabs, and thicker reactive wind slabs in unusual places as the winds shifted from west to northeast. Sunny weather is likely making the wind slabs extra touchy on south-facing slopes. The mid-December facet/surface hoar interface can be found buried 50-100 cm deep. The interface has been showing signs of gaining strength in thick snowpack areas, but remains a concern in thin snowpack areas throughout the region. The lower snowpack is well bonded and features a thick rain crust near the ground.
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.