Avalanche Forecast

Issued: Jan 11th, 2016 9:02AM

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

swerner, Avalanche Canada

Purcells.

The regional snowpack remains quite variable. It's important to be in tune with the conditions in your local riding areas.

Summary

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

The weather pattern is finally changing. A weak frontal system will break down the persistent valley cloud and temperature inversions bringing upper elevation clouds, snow accumulations 3-7 cm, and light SW winds. Freezing levels near 1200m. By Wednesday the Purcells may see an additional 5-10 cm of new snow with strong SW winds and alpine temperatures near -10. Unsettled conditions continue through Thursday.

Avalanche Summary

On Sunday, a natural icefall off a hanging glacier occurred, size 2 but did not pull a slab from the slope below. A cycle of naturally-triggered size 1 loose dry avalanches from steeper terrain features were also reported.

Snowpack Summary

New surface hoar growth exists primarily on shady aspects at treeline and above. The upper snowpack is generally loose and unconsolidated with 15-30 cm of snow sitting above a variety of old surfaces including surface hoar, facets and crusts. In isolated locations wind or storm slabs may exist. In parts of the Purcells, two prominent layers of buried surface hoar continue to be reactive in snowpack tests. These are buried down 25-60 cm and may be reactive where a cohesive slab sits above. Shallow snowpack areas and moraine features may also have weak faceted snow near the ground that will require time and some warming to strengthen.

Problems

Wind Slabs

Wind slabs may be lurking on leeward slopes and behind terrain features, especially where they are sitting on weaker layers buried below. Loose dry sluffing is possible from steep terrain and may have enough mass to push you around or bury you.

Use ridges to avoid pockets of wind loaded snow. >On steep slopes, pull over periodically or cut into a new line to manage sluffing.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

A low probability/ high consequence persistent slab problem still exits. Investigate your local snowpack.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved, especially in the south of the region.>Avoid exposed alpine faces, especially in the north of the region.>Dig down to find and test weak layers before committing to a big line. >

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely

Expected Size

2 - 4

Valid until: Jan 12th, 2016 2:00PM