Fresh and reactive wind slabs will continue to form as the winds increase over the next couple of days.
Summary
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A change in the weather pattern is upon us as the upper jet shifts to a westerly flow allowing a series of Pacific frontal systems to track across the Interior regions.Monday night-Tuesday: Cloudy with snow amounts 5-10 cm, however snow amounts may be greater to isolated convective activity. Alpine temperatures near -12 and ridgetop winds light with strong gusts from the SW. Wednesday: Cloudy with possible sunny breaks and snow amounts 5-10 cm. Alpine temperatures near -10 and ridgetop winds moderate with strong gusts from the West. Thursday: Mostly cloudy with a trace of new snow. Alpine temperatures near -8 and ridgetop winds light from the SW. Freezing levels rising to 1200m.
Avalanche Summary
On Sunday, numerous natural loose dry avalanches up to size 2 were reported from the Lizard Range. More significantly, a natural size 2.5 was also reported which started in the recent storm snow then stepped down to an older storm snow interface. Most of the recent avalanche activity was on northerly aspects above 1500m. Last week proved several notable deep persistent avalanches including explosive control near Fernie, this avalanche was size 2.5 on a north aspect at 2000 metres, and is believed to have released on the mid-December facets. Last Tuesday a natural avalanche size 3.5 on Mt Hosmer on an East aspect at 2100 metres that appears to have released on, or stepped down to the weak deep persistent layer near the ground. Last Wednesday a size 3.0 avalanche was reported on "Big Steep Mother" bowl on a northeast aspect at 2100 metres. This avalanche appears to have been started by a cornice fall that released a storm slab that then "stepped down" to deeply buried weak facets.
Snowpack Summary
Up to 40 cm of cold, light density storm snow fell Saturday night with little wind. This recent storm snow rests on an older wind/storm slab that formed last week that is approximately 50 to 60 cm in depth and may still be sensitive to human triggering. This older slab sits above a thick rain crust below 1900 m and a generally well settled snowpack. Isolated basal weaknesses may still exist in shallow snowpack areas. Smaller avalanches may have the potential to step down to those weaker layers waking up the deep persistent slab problem. These weak areas appear to be on north-northeast aspects in the alpine.
swerner,
Avalanche Canada
