Human triggering and some natural avalanche activity continues to occur on the various weak layers buried in our snowpack. We expect this to increase Sunday night and Monday. Minimize exposure and avoid large avalanche terrain until things improve!
Weather Forecast
Temps on Sunday will be in the -5 to-10'C range at treeline with some warming late in the day and 10-15 cm of snow, mostly later in the day. Sunday night should see a rise in temperatures and increased snowfall into Monday which will likely cause a natural avalanche cycle if the current forecast comes true.
Snowpack Summary
Recent alpine winds have created wind slabs in leeward areas up to 1m thick. 35-65 cm of settled snow from recent storms has formed a soft slab over the three persistent weak layers of surface hoar and facets that lurk in the upper half of the snowpack often giving sudden test results. Jan 16 down 35-65cm; Jan 6 down 40-75cm; Dec15 down 55-100cm
Avalanche Summary
More evidence of a widespread cycle on persistent weak layers up to size 3 in the last 48hrs was observed with debris crossing the Takkakaw Falls road below Wapta Peak and numerous slabs out at treeline in the Yoho Valley. One natural size 2.5 cornice triggered slab was observed on Mt Crowfoot near the Wapta Icefields this morning.
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Monday
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.