Regions
Banff Yoho Kootenay.
http://www.pc.gc.ca/apps/links/goto_e.asp?destination=Highway 93 south avalanche control is scheduled for Monday. Please avoid the Simpson slide paths and Mt Wardle.
Weather Forecast
A relief from the arctic air flow will come Monday with a gradual warming trend through the day. Expect a daytime high of -5 with clear skies and light winds. As the westerly flow moves in, light precipitation will bring 5cm Tuesday. With warming temperatures and clear skies on Monday there will likely be some solar input into the snowpack.
Snowpack Summary
Moderate to strong winds have redistributed the recent storm snow forming wind slabs at higher elevations. The three main mid-pack concerns are the Jan 16th, Jan 6th, and Dec.15 weak layers. These are a mix of facets, crusts and surface hoar and can be found 70cm to over 150cm deep in the snowpack and have been producing very large results.
Avalanche Summary
The bulk of the recent avalanche cycle has tapered off. Reports of isolated skier and explosive triggered wind slabs were noted today from local ski patrol. All avalanche terrain is still highly suspect.
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.