There are significant differences in the snowpack in the forecast area. Remote triggering on low angle terrain has been reported in Whistler/Portal Creek area. Tests such as ski cutting and pits are not reliable. Avoid steep unsupported slopes.
Weather Forecast
Flurries to produce 10 cm by Wednesday. Winds expected to be light. Temperatures and freezing level steadily falling into the middle of the week.
Snowpack Summary
Warm flurries coming in with light SE wind are forming wind slab in lee and cross-loaded terrain above 2000m that are bonding well. The persistent slab is down 40-70cm and is easily triggered in the Whistler/Portal areas even on low angle slopes but is stubborn in the Icefields. Lower snowpack is facetted is extremely weak.
Avalanche Summary
No new observations today but reports of numerous remotely triggered avalanches to size 2 on slope angles as little as 15 deg around Marmot Pass along with widespread whumphing and cracking. Whumphing and cracking also noted in the Maligne area. In contrast, no reports of any propagations in the Icefields area.
Confidence
Due to the number and quality of field observations 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.