Avalanche Forecast

High

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.

Numerous explosive triggered storm slab avalanches up to size 2.5 were reported on primarily sunny aspects at treeline and above on Thursday. They were failing on a crust down 30-40 cm.

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.

Strong solar radiation has settled the 30-50 cm of recent snow into a storm slab which has remained reactive to human triggers in specific locations at upper elevations.

Strong south wind during the storm earlier in the week added to slab formation on lee aspects at treeline and above.

The recent snow is sitting on a variety of surfaces. These include sun crust on sunny aspects and surface hoar (3-5 mm) on some shady and sheltered slopes.

A 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.

Saturday Night

Clear skies / 10 km/h east ridgetop wind / Temperature at treeline around -6 C / Freezing level valley bottom

Sunday

Sunny / 20 km/h southeast ridgetop wind / Temperature at treeline around 0 C / Freezing level 1900 m

Monday

Mostly cloudy / 20 km/h east ridgetop wind / Temperature at treeline around -3 C / Freezing level 1600 m

Tuesday

Sunny / 10 km/h east ridgetop wind / Temperature at treeline around -3 C / Freezing level 1600 m

More details can be found in the Mountain Weather Forecast.

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