While the likelihood of triggering persistent slabs is being reduced by cooling temps, the consequences remain the same. A cautious approach is recommended for the foreseeable future.
Weather Forecast
Tonight: flurries with trace amounts, freezing level 1300m, Alpine temps lows -7 °C, wind moderate west. Friday: flurries giving up to 5cm, freezing level to valley bottom, and similar winds.Forecast: Sat and Sun freezing level between 1500m-2000m. 6cm Sat and Sun 26cm. Winds SW mod gusting strong.
Snowpack Summary
Cooling temperatures forming a new surface crust on the saturated upper snowpack below 2300m. A persistent slab of between 40cm - 200cm sits over the Halloween Crust. This crust can be found up to 2,700m in the Icefields and depending on its location is between 20cm - 40cm above the ground. Wind slabs likely exist in the upper alpine.
Avalanche Summary
Numerous persistent slab avalanches to size 2.5 observed from field teams today. These were failing at treeline and in the lower alpine as a result of warm temperatures, rain and additional snow loading. On Nov. 22nd a field team remote triggered 3 simultaneous size 2 persistent slabs 60-150m away.
Confidence
Due to the number and quality of field observations
Problems
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.