Considering the forecast, we recommend avoiding accessing Maligne Lake, Whistler and Portal Creeks Thursday and into the weekend to allow the region to stabilize with the new load.
Weather Forecast
Forecasted south wind and snow, up to 10cms overnight and continued snowfall over the day with total forecasted amounts to near 30cms. As the storm progresses the winds are expecting to increase from moderate to strong values. Temperatures to remain cool but freezing levels up to 2000ms in the Icefields.
Snowpack Summary
Maligne/Jasper: Variable snow depth above tree-line, relative to exposure. Average HS 70cm. Surface wind slabs and persistent slab down 40-90cm, very touchy, even on low angle slopes Icefields: Variable snow depth above tree-line, relative to exposure. Average HS 120cm. Cornices and building wind slabs overlaying supportive mid pack and weak base.
Avalanche Summary
Field teams in the Maligne/Bald Hills with good visibility. Large destructive avalanches noted in the area up to size 3, one measuring 900ms in length at the crown. Potential for human triggered is very likely. Not expected to get any better with new forecasted storm snow. No reports of any significant avalanche activity in the Icefields area.
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Thursday
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.
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.