Wind slabs are expected to be the main concern for most of the region on Thursday. However, in the deeper snowfall areas of the region, a more widespread storm slab could develop and the local danger could reach HIGH during the peak of the storm.
Summary
Confidence
Low - Intensity of incoming weather systems is uncertain on Thursday
Weather Forecast
The last major low pressure system is expected to bring periods of heavy snowfall to the region on Thursday. 5-10 cm is expected Wednesday overnight and 15-25 cm is expected on Thursday. Alpine wind is forecast to be strong from the southwest on Thursday and freezing levels are expected to reach around 800 m elevation. Mostly dry and sunny conditions are expected for Friday with light alpine wind and freezing levels around 600 m. A weak storm pulse is forecast to bring around 5 cm of snow on Saturday with strong alpine wind from the northwest.
Avalanche Summary
On Wednesday, ski cutting results were limited to two size 1 wind slab avalanches. On Tuesday, explosives and ski cutting produced soft slab avalanches up to size 1.5 which were confined to the new storm snow. On Thursday, wind slabs are expected to be the primary concern in the region. However, if we get higher snowfall amounts than expected, there is a potential for storm slab formation. Where this happens, the local danger rating could be higher.
Snowpack Summary
20-40 cm of new snow has accumulated since Monday. This new snow sits over a variable interface which consists of wind affected surfaces, faceted (sugary) snow, or surface hoar. Recent observations suggest the new snow is well bonded to this interface with exceptions for isolated areas where surface hoar may be preserved. Recently strong southerly winds have formed wind slabs in leeward and cross loaded features in wind exposed terrain. The mid-December interface is now down 90-120 cm and is generally considered to be stable in most areas.
rbuhler,
Avalanche Canada
