Mild temperatures and sunny periods could make avalanche problems more prone to triggering. Stay tuned to signs of instability like recent avalanches or critical warming.
Weather Forecast
Synopsis: We could see cloud and flurries early on Thursday before a ridge of high pressure builds in and results in clearing skies. The freezing level remains near valley bottom with slightly cooler temperatures and winds should be light. Expect a mix of sun and cloud on Friday and theres a chance we could see a thin above freezing layer (AFL) near mountaintop. Saturday looks like a mixed bag with cloud, sunny breaks, and a chance of flurries. The freezing level is at valley bottom and the AFL should disappear.
Avalanche Summary
On Tuesday, there was one report of a size 2.5 natural slab avalanche from Allison Peak in the Crowsnest Pass. A couple observers also reported easily skier or sled triggered avalanches up to size 1.5 involving the recent storm snow (average 20 cm deep).
Snowpack Summary
Up to 20 cm of recent snowfall has been shifted into wind slabs in upper elevation terrain by moderate to strong westerly winds. These new accumulations overlie hard wind slabs in exposed terrain, and low density faceted snow in sheltered areas. Up to 75 cm below the surface you will likely find a hard, thick crust which formed mid-December. This crust has overlying facets and surface hoar (up to 10 mm in sheltered locations at treeline and below). This layer seems variably reactive throughout the region. In areas where the overlying slab is thick and cohesive, large avalanches are possible at this interface. A crust/facet combo which formed in November seems to have gone dormant for the time being.
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.