Kootenay Boundary

The deep mid-Dec layer remains reactive and there have been several avalanches in the last few days. Use a conservative approach and assess conditions before committing to big terrain features.

Fair - Timing, track, or intensity of incoming weather system is uncertain

Light flurries are possible on Thursday morning. Freezing levels are expected to be around 1000m and alpine winds should remain light. Friday will be unsettled in advance of a frontal system which is expected to arrive in the evening. Friday should be mostly cloudy with freezing levels around 1000m and light alpine winds. Around 5mm is expected Friday night with moderate SW winds. On Saturday, freezing levels are forecast to climb to around 2500m. Another 5-10mm are expected for Saturday.

On Tuesday, one natural avalanche was reported. A cornice broke off and triggered a deep slab avalanche on the mid-Dec layer. Three skier triggered avalanches were also reported and these all released on the mid-Dec surface hoar layer. Depths varied from 30cm to 100cm with typical values around 70cm. On Monday, a natural size 1.5 storm slab was reported. This released down 25-40cm on the mid-Jan surface hoar. Also reported were a few ski cuts and explosive triggered avalanches. These were typically size 1.5-2 and released on the mid-Jan layer. These occurred on north through east aspects between 1900 and 2100m. Natural avalanche activity is generally not expected on Wednesday but remains possible in isolated areas such as steep sun exposed slopes or wind loaded areas. Human-triggering is likely in wind loaded areas and steep terrain features, especially where surface hoar underlies the recent storm snow.

Around 30cm of snow sits on the mid-Jan surface hoar layer. In many places the surface hoar sits above a thin crust that can be found up to about 1900m on north aspects and all the way to ridgeline on south aspects. Strong SW winds during the storm loaded leeward features and the persistent slab may be 50-60cm thick in wind loaded areas (typically north through east aspects). A deeper crust/surface hoar combo buried in mid-December continues to be a concern. This layer can typically be found down 70-100cm. The reactivity of this deep persistent weak layer appears to have become isolated but still has the potential for large, destructive avalanches in some areas. The layer has been the most reactive at and just below treeline.