Regions
Banff Yoho Kootenay.
Mod. to strong winds from the S/SW are creating a fresh instability to watch out for. Periods of strong winds will also increase sluffing out of steep terrain (ice climbers beware). Winds should ease on Friday allowing the danger to decrease.
Weather Forecast
Thurs overnight: Alpine temps -10/-15. 2-5 cm snow. Alpine winds moderate from the SW.Fri: Alpine temps -10/-15. Clearing skies, trace precip. Alpine winds light from the SW.Sat: Alpine temps -10/-15. Overcast, trace precip. Alpine winds light from the S.Sun: Alpine temps -10/-15. Overcast, trace precip. Alpine winds light from the SW.
Snowpack Summary
10-20 cms of new snow overlies a well settled midpack. At ridgetop elevations, moderate to strong S/SW winds are forming 15-30 cm soft slabs in the immediate lee on N through E aspects. The Nov. 6th crust is facetting out, and is now more of a facet layer than a crust in many places. This layer is giving hard to no results in compression tests.
Avalanche Summary
Limited observations by Parks staff today. Reports of ski cutting soft slabs in wind loaded areas by ski patrol at Sunshine and loose snow sluffing out of steep terrain with increased winds.
Confidence
Due to the number of field observations on Thursday
Problems
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.