Avalanche Forecast
Issued: Jan 7th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
MBender,
Avalanche Canada
Skies are clearing after a stormy week. It may be tempting to get into bigger terrain, however persistent slab avalanches continue to be reported. The best and safest riding will be found in mellow wind sheltered terrain.
Summary
Confidence
Weather Forecast
Thursday Night: Mainly cloudy with clear periods, light to moderate south wind, alpine high -6.
Friday: Mainly cloudy with sunny breaks and isolated flurries, moderate south wind, alpine high -4, freezing level 700 m.
Saturday: Isolated flurries, moderate southwest wind, alpine high -5, freezing level 600 m.
Sunday: Flurries, light southwest wind, alpine high -5.
Avalanche Summary
Reports on Wednesday and Thursday indicate several explosives triggered size 2 storm slab avalanches on northerly and southerly aspects at treeline and in the alpine. There was also a report of a size 2 storm slab avalanche that was triggered by another smaller avalanche running nearby. This was at 1950 m on a northeast aspect. As well on Thursday there was a report of 3 explosives triggered size 2.5-3 persistent slab avalanches on north through southwest aspects at 2100 m.
On Tuesday there was a report of a naturally triggered size 2.5-3 wind slab avalanche which stepped down mid-path to the early December persistent weak layer. This was on an east aspect near ridgetop and occurred in the central part of the region. As well there were reports of several explosives controlled size 2 storm snow avalanches in Kootenay Pass on southerly aspects between 1800 and 2100 m.
A remotely triggered (from a distance) size 2 persistent slab avalanche was reported near Rossland on Sunday. The details can be seen in MIN posts here and here.
Snowpack Summary
40-70 cm of recent storm snow accumulating over the past week has seen wind affect at upper elevations. In sheltered areas, the recent snow may sit over surface hoar.
Two weak layers are buried in close proximity to one another. They are 70-100 cm deep around Nelson and 50-80 cm deep around Rossland and other western parts of the region. The layers are composed of feathery surface hoar and sugary faceted grains and they overlie a hard melt-freeze crust.
Terrain and Travel
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Be especially cautious as you transition into wind affected terrain.
- Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Storm Slabs
Storm slabs may remain sensitive to human triggers, especially in freshly wind loaded features at upper elevations and where recent snow sits over surface hoar in wind sheltered areas.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Weak surface hoar and/or faceted grains sit above a melt-freeze crust 70 to 100 cm deep. This layer has been steadily stressed as new snow slowly piled up over the past week.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 8th, 2021 4:00PM
