Avalanche control will necessitate intermittent closures along the Icefields Parkway over the next few days. Visit Alberta's Road Report at www.511.alberta.ca for the most up to date info on road closures throughout the week.
Weather Forecast
10cm by Monday evening, then intensity of precipitation expected to increase through the week with as much as 30-40cm by next weekend. Temps to remain cool and winds predominantly light Southwest with the exception of Sunday overnight when winds will be moderate, gusting strong.
Snowpack Summary
Recent snowfall overlies a layer of small surface hoar and surface facets. A relatively hard mid-pack is providing bridging strength over weak basal facets at tree line and above. Below tree line has a supportive (albeit shallow) mid-pack. Recent wind loading has produced touchy new slabs on Easterly terrain at treeline and above.
Avalanche Summary
Skier accidental yesterday at Marmot basin - size 1.5 on steep Easterly aspect below ridge top at 2100m. This slab was formed by recent loading of the new snow in the past 3 days and slid on the crust/facet interface down 40cm. No natural activity observed on road patrol between Jasper and Saskatchewan crossing yesterday.
Confidence
Intensity of incoming weather systems is uncertain
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.