Kootenay Boundary

Lingering wind slabs may remain reactive to human triggers on northerly aspects in the alpine.

Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.

Numerous explosive triggered wet loose avalanches up to size 2 were reported on sunny aspects at upper elevations near Kootenay Pass on Saturday.

A large (size 2.5) rider triggered wind slab was reported on a north aspect in the alpine on Friday. The avalanche was triggered from the ridge top and the reported weak layer was surface hoar. See MIN.

Additionally, a snowmobile triggered a large persistent slab avalanche (size 2.5) just north of this region near Haystack mountain (west of Cranbrook). The avalanche occurred in burnt forested terrain on a south aspect at 2200 m. It failed on a 50 to 100 cm deep layer that is suspected to be a sun crust buried in February.

Expect to find a melt-freeze crust on the surface of all aspects at treeline and below and on sunny aspects in the alpine. Solar radiation will break down the crust on sunny slopes throughout the day.

Lingering wind slabs may remain reactive to human triggers on northerly aspects in the alpine.

30-50 cm down there is a sun crust on sunny aspects and surface hoar (3-5 mm) on isolated shady and sheltered slopes.

Another layer of surface hoar or sun crust, aspect dependent, that was formed in mid-February can be found down 80 to 110 cm.

The lower snowpack includes a layer of weak sugary facets near the ground. These facets are slowly gaining strength and no recent avalanches have been reported on this layer. However, we continue to track the layer and watch for any signs of it becoming active.

Sunday Night

Partly cloudy / 20 km/h east ridgetop wind / Temperature at treeline around -3 C / Freezing level 700 m

Monday

Mostly cloudy / 20 km/h northeast ridgetop wind / Temperature at treeline around -4 C / Freezing level 1600 m

Tuesday

Sunny / 10 km/h northeast ridgetop wind / Temperature at treeline around -3 C / Freezing level 1700 m

Wednesday

Sunny / 10 km/h north ridgetop wind / Temperature at treeline around 0 C / Freezing level 1900 m

More details can be found in the Mountain Weather Forecast.

• Minimize exposure to sun-exposed slopes when the solar radiation is strong.
• A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
• Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
• Cornice failure may trigger large avalanches.
• Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.