Between 5-14 cm of new snow is forecast to fall over the next 24hrs. This snow will fall under the influence of STRONG chinook flow so watch for new windslabs to build in alpine areas.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Saturday
Weather Forecast
Overnight on FridayFlurries.Accumulation: 8 cm.Alpine temperature: Low -6 C.Ridge wind southwest: 75 km/h gusting to 115 km/h.Freezing level at valley bottom.Saturday throuhgout the day. Mainly cloudy with isolated flurries.Precipitation: Trace.Alpine temperature: High -7 C.Ridge wind west: 50 km/h gusting to 110 km/h.Freezing level at valley bottom.
Avalanche Summary
No new avalanche activity was observed on Friday.
Snowpack Summary
Below 1900m, the temperature crust from last week is now buried by 8cm of snow. This crust is unlikely to pose any problems down the road. The snowpack has regained some of it strength down low and is now more supportive in many areas. At treeline, the windslabs start to become evident in open areas or areas exposed to wind. Windslabs are down 20cm and only an issue in isolated areas. The Jan 6th layer is down 50-70cm at upper treeline and is hanging in there in terms of strength with the other layers. The alpine is either weak and facetted or a series of laminated windslabs. The exposure to wind seems to be the deciding factor.
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.