Be cautious in areas with thin snowpacks, especially shallow rocky spots. A fresh round of windslabs may be lurking near ridge crests.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
We've had a bit of a shift from the very cold conditions, and temperatures have warmed by 5 - 10 degrees Celcius. Only some isolated flurries are possible until late Sunday, when a small amount (5-10 cms) of light dry snow is forecast.SATURDAY: Sunny breaks with increasing clouds overnight. Flurries overnight with little accumulation. Winds light southerly. Alpine highs to -13 Celcius.SUNDAY: Cloudy with sunny breaks. Winds light southerly. Alpine temperatures between -15 and -20 Celcius; 5-10 cms light dry snow overnight.MONDAY: An additional 5-10 cms light dry snow are possible during the day and overnight. Winds light - moderate southwesterly. Alpine temperatures steady near -14 to -18 Celcius.
Avalanche Summary
No new avalanches observed.
Snowpack Summary
Another round of moderate northerly winds has moved through the Crowsnest pass and northern areas in the past 24 hours, causing fresh wind slabs on south and west aspects. In some areas these wind slabs may be sitting on an old scoured surface that was stripped by previous strong westerly winds that developed wind slabs on north and east aspects. The newer wind slabs are probably easier to trigger, but the old wind slabs may continue to release with the added load of a rider, especially where they are sitting on a shallow weak sugary base. The mid snowpack is generally right side up, with the mid-December interface down 40-80cms, giving inconsistent results in snowpack tests. There is some faceting below this interface but resistances are good and showing signs of rounding (stabilizing). Travel conditions have been challenging (especially at lower elevations) and little change is expected until a significant warm up helps to settle the snowpack.
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.