Recent snow and wind has created fresh windslabs in many leeward alpine locations. Take note that many small slabs were observed in steep couloirs on Saturday.
Weather Forecast
A clear-ish morning will be followed by increasing cloud and light precipitation. Light precip will continue until late on Wednesday when a front will deposit up to 15cm of new snow. Throughout the period, temperatures at the valley bottom will be just above zero. Wind will remain in the Mod/Strong (West) range through tonight and then dissipate.
Snowpack Summary
Up to 15cm recent snow at upper elevations. Melt-freeze crusts are common. On North and East aspects in the alpine, up to 30cm of unconsolidated snow can be found. Below this, a stiff slab overlying weak facets remains a concern in some places and a weak, faceted snowpack, remains a concern in thin areas.
Avalanche Summary
On a flight to the Wapta Icefields and through the Lake Louise group, forecasters observed several size 1 windslabs. These were typically on North aspects on alpine features, and often were observed having pulled out at the top of fans (bottoms of couloirs). While risk of burial is low, the risk of being carried to an undesirable location is there.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
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.