Avalanche Forecast

Issued: Feb 10th, 2016 8:31AM

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

ccampbell, Avalanche Canada

Purcells.

Triggering large avalanches remains possible. Keep it conservative until things cool off and the snowpack settles.

Summary

Confidence

High

Weather Forecast

THURSDAY: Clearing throughout the day with freezing levels around 1800m and light variable winds. FRIDAY: Mainly cloudy with light snow bringing as much as 5cm. Freezing levels reaching 1700m and light southwesterly winds. SATURDAY: Mainly cloudy with continued light snowfall totalling 5cm of accumulation. Freezing levels should drop to 1600m and winds are expected to be moderate from the southwest.

Avalanche Summary

Reports from Tuesday include several natural storm and wind slab avalanches up to Size 3 at various elevations. Fresh natural persistent slab avalanche activity was also observed, with a report of two Size 2.5s in the Kicking Horse backcountry, which released on a surface hoar, facet and crust weakness as deep as a metre down. A continued cycle of natural loose wet sluffs reaching Size 2 on sun-exposed slopes was also reported.

Snowpack Summary

Wet surface snow has refrozen into a supportive crust in most places; however, dry soft snow with new surface hoar growth may be found at treeline elevations and below on shaded aspects. Strong to extreme winds on Saturday created wind slabs and cornices in many areas, and scoured north and west-facing alpine slopes. The early January surface hoar/ facet layer is typically down 70-90 cm. Recent very large avalanches have been failing on this interface in the north of the region (see avalanche discussion). In general, the lower snowpack below this layer is well settled and strong, apart from some thin snowpack areas where basal facets exist.

Problems

Wind Slabs

Recently formed wind slabs lurking below ridgecrests and behind terrain features remain sensitive to human triggers.

Travel on ridges to avoid freshly wind loaded features. >Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

A deeply buried weak layer can still be triggered in some places, creating very large avalanches.

Be cautious around open slopes and convex rolls at and below treeline where buried surface hoar may be preserved. Big alpine features are also suspect.>Avoid thin, rocky or sparsely-treed slopes.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Feb 11th, 2016 2:00PM