Avalanche Forecast

Issued: Mar 8th, 2016 8:30AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

triley, Avalanche Canada

Purcells.

Some areas in the west of the region near Kootenay Lake have received much more snow, and these danger rating may be too low. If your area has more than 20 cm of new snow, the danger may be considerable or higher.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

Freezing down to valley bottoms overnight with light precipitation and moderate southwest winds. A mix of convective flurries and sunny breaks on Wednesday with moderate southerly winds and freezing level climbing to 1500 metres during the day. Strong southwest winds developing Wednesday night with moderate precipitation and freezing levels up to 1600 metres. Storm continuing on Thursday with moderate precipitation and freezing levels at 1900 metres. Mostly sunny on Friday with light winds and freezing levels remaining above 1500 metres.

Avalanche Summary

Natural avalanches up to size 3.0 were reported from the west central part of the region near Kootenay Lake. The north of the region had a few reports of stubborn wind slab avalanches to size 1.5 on Monday. A few small natural avalanches and a couple of size 2.0 explosives controlled avalanches were reported on Sunday. Natural wind slabs and storm slabs up to size 2.5 were reported on Saturday.

Snowpack Summary

Close to 30 cm of new snow fell overnight in the west central part of the region near Kootenay Lake. The new storm slab was isolated to this area. The north and east of the region only received a few cm overnight combined with moderate winds. Recent strong southerly winds have developed wind slabs in the alpine and at treeline in most of the region. The 20-40 cm of recent storm snow is bonding poorly to a melt-freeze crust on previously sun-exposed slopes and lower elevation terrain, and/or a layer of surface hoar on shady and sheltered slopes at treeline elevations. The surface hoar and/or crust layer buried in mid-February is now down 50-80cm. The early January surface hoar/facet layer is typically down 70-120cm. Triggering an avalanche on this layer has become unlikely but it still has isolated potential to produce very large avalanches with a heavy trigger. In general, the lower snowpack is well settled and strong, apart from some thin snowpack areas where basal facets exist.

Problems

Wind Slabs

Recent wind slabs may be triggered by skiers and riders in the immediate lee of alpine features and treeline ridges.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

The weak surface hoar layer that was buried on February 27th is now down 30-50 cm and continues to allow for long fracture propagations. Wind slabs in motion or cornice falls may step down to this persistent weak layer.

Caution around convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Mar 9th, 2016 2:00PM