Avalanche Forecast
Issued: Feb 16th, 2018 5:30PM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Moderate - Forecast snowfall amounts are uncertain on Saturday
Weather Forecast
The south of this region will see significantly more snow from the storm on Saturday (25-30cm possible). Clearing and becoming cold on Sunday as frigid arctic air moves in. Saturday: Snow (25-30 cm possible in the far south with 10-15 cm near Nakusp). Tree line temperature around -8 Celsius. Winds southwesterly 30km/h.Sunday: Clearing, but lingering flurries possible. Tree line temperatures around -14C. Winds light northeasterly.Monday: Sunny but cold. Alpine temperatures near -18 Celsius. Winds light northerly.
Avalanche Summary
On Friday some locations in the Monashees had locally heavy snowfall amounts resulting in very reactive storm slabs to size 1.5, with crowns 20-40cm thick. On Wednesday, at least five human-triggered avalanches were reported up to size 2 on north, east and south-facing slopes and elevations between 1800 and 2300 m. The releases appeared to be at the base of the most recent storm snow and a crust was reported in some of them, most likely those on more southerly aspects.In Rogers Pass on Monday, skiers remotely triggered a size 3.5 persistent slab avalanche from 40 m away on a south-facing, cross-loaded slope at 2600 m. On the same day, a helicopter remotely triggered a size 3 persistent slab avalanche on a similar aspect/ elevation in the Selkirks a little closer to Revelstoke. Although deeper, persistent avalanche activity is becoming less frequent, these recent avalanches point to the continued reactivity and destructive potential of these layers.
Snowpack Summary
30-40 cm of recent storm snow has settled into a slab in the upper snowpack. Strong winds, most recently from the northwest, shifted these accumulations into deeper, reactive slabs in wind-exposed terrain. These accumulations overlie a mix of older wind slabs in exposed higher elevation terrain, a sun crust on steep solar aspects, a rain crust below 1600m and surface hoar on sheltered slopes.Below the snow surface several persistent weak layers make up a troublesome snowpack. In the top 1.5-2.5 m of the snowpack, two surface hoar/ crust layers buried in January can be found. Expect to find one or the other of these on all aspects and elevations.Deeper in the snowpack (around 200 cm deep) is a facet/crust/surface hoar layer from December, most prevalent at and below treeline.Near the base of the snowpack is a crust/facet combo, most likely to be triggered from thin spots in the alpine.All of these layers have produced large avalanches recently. The wide distribution and ongoing reactivity of these layers suggests that avoidance through choosing simple terrain is the best strategy.
Problems
Storm Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 17th, 2018 2:00PM