Regions
Northwest Inland.
Strong winds have created very touchy wind slabs. Be cautious in terrain features where snow has accumulated, as the slabs will likely be easy to trigger.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
MONDAY: Partly cloudy with increasing cloudiness, moderate northwesterly winds, alpine temperature -12 C, freezing level below valley bottom.TUESDAY: Mostly sunny, light to moderate northerly winds, alpine temperature near -10 C, freezing level below valley bottom.WEDNESDAY: Mostly sunny, moderate to strong northerly winds, alpine temperature near -9 C, freezing level below valley bottom.
Avalanche Summary
Many small to large (size 1 to 2) wind slabs were reported on Saturday in steep alpine and cross loaded terrain. They were reported to have released naturally and by skiers due to rapid wind loading from strong northeasterly winds.Avalanche activity may slow down with a period of cold, clear weather expected to persist well into the week, unless the sun is powerful enough to warm the snow surface. Watch for steep sunny slopes due to the sun’s influence, lee features for reactive wind slabs, and be extra cautious near thin spots and shallow snow pack areas where triggering a deeper weak layer is more likely.
Snowpack Summary
Northerly to easterly winds have created stiff wind slabs on leeward slopes and scoured wind-exposed slopes at all elevations.Deeper in the snowpack, a crust and/or weak surface hoar layer buried in mid-January now lies about 60 to 100 cm below the surface. The crust exists well into the alpine and the surface hoar can be found in sheltered areas in lower alpine and tree line elevations. Snowpack tests have produced hard, sudden results on weak, sugary snow crystals associated with this crust in the Smithers area, indicating that this is still a layer of 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.