Lots of snowpack variability exists between the west and east sides of the region. Click the Forecast Details tab for more info.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
On Tuesday night up to 15cm of new snow is expected with generally light to moderate ridgetop winds. By the afternoon, we should expect a mix of sun and cloud and light northwest winds. On Thursday and Friday a series of Pacific systems will move through the region bringing up to 5cm of new snow and strong southwest winds each day. Freezing levels should sit at valley bottom on Wednesday and then rise to about 1800m on Thursday and Friday.
Avalanche Summary
In the Elk Valley North area on Tuesday, several natural wind slab avalanches to size 1.5 were observed in wind-loaded, high elevation terrain. A size 1 persistent slab avalanche was also noted on a steep cut bank below treeline. New wind and snow on Tuesday night may promote a new round of wind slab activity. In areas where buried persistent weak layers exist, new snow will also add to the likelihood and consequences of triggering the overlying slab.
Snowpack Summary
Up to 15cm of new snow may fall on Tuesday night. If ridgetop winds are moderate or greater, I would expect fresh and reactive wind slabs to form in high elevation lee terrain. East of Crowsnest Pass any new snow will overlie mainly scoured surfaces or hard stubborn wind slabs from last week. In general, the mid and lower snowpack are strong and well-settled in these areas.In areas to the west of the divide you're more likely to find a mix of persistent weak crystals which may lie up to 30cm below the surface. These crystals, which formed at the beginning of January, seem most reactive in open areas below treeline and consist of surface hoar, facets and a hard crust on steep solar aspects. Additional snow load will add to the size and reactivity of this developing persistent slab.
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.