Strong winds will increase the avalanche danger in the upcoming days.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
MONDAY: Cloudy with isolated flurries, west winds increasing throughout the day reaching 50 km/h in the afternoon and 80 km/h overnight, alpine temperatures around -12C.TUESDAY: Flurries with accumulations of 5-15 cm, 40-60 km/h west winds, alpine temperatures around -8C.WEDNESDAY: Mix of sun and cloud with isolated flurries, strong west winds, alpine temperatures around -10C.
Avalanche Summary
On Saturday, ski cutting produced size 1 loose dry avalanches in the new low density snow. Skiers in Kananaskis Country remotely triggered a size 2 avalanche from 35 m away on Friday. The avalanche was a wind slab over a weaker facets, which closely resembled snowpack conditions in the South Rockies.Triggering persistent slab avalanches on weak interfaces that formed in early December are the primary concern. Triggering these layer is most likely in wind-affected terrain where the weak layers are covered by hard wind slabs. In the southeast corner of the region, explosive results suggest there are also weak facets near the ground that may be possible to trigger from thinner snowpack areas.
Snowpack Summary
Recent flurries delivered 10-15 cm of low density powder. The fresh snow covers hard wind slabs from a storm last week. A variable interface that formed during the cold snap in early December can be found 20-40 cm under the new snow. This interface consists of hard wind packed snow in exposed terrain, weak faceted (sugary) snow, and feathery surface hoar up to 20 mm in sheltered areas. This interface will likely evolve into a lingering persistent slab problem as the recent storm snow settles into a slab. 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
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.
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.