Confidence
Fair - Due to the number of field observations
Weather Forecast
On Tuesday, a low pressure system will move across central BC. While the system is expected to miss the South Rockies, the associated warm front will cause freezing levels to rise even higher, up to around 2300m. A weak ridge of high pressure will build after the low passes. The associated cold front on Wednesday will bring light snowfall to the region. Another low pressure system is expected to hit the coast on Thursday.Tuesday: A mix of sun and cloud, freezing levels as high as 2300m, moderate westerly alpine windsWednesday: Light snowfall, freezing levels dropping to valley bottom, light SW winds switching to NE during the dayThursday: A mix of sun and cloud, light NE winds switching to SW during the day
Avalanche Summary
No new avalanches reported.
Snowpack Summary
Recent incremental snowfall has started to bury the mid-Dec surface hoar and the previously faceted upper snowpack. Snowpack depths at treeline seem to vary from 50 - 110 cm with high variability in wind-exposed areas. Buried surface hoar/facets/crust (late-Nov interface) are down approximately 30-40cm. The base of the snowpack is made up of weak facets and depth hoar. This deep persistent weakness may be stubborn to trigger, especially in deeper snowpack areas, but the sensitivity to triggers likely increases in shallower locations, especially on a steep, convex slopes. In some below treeline areas the snowpack is below threshold and early season hazards like open creeks and stumps remain a 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.