Avalanche Forecast

Issued: Jan 9th, 2012 9:20AM

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.

Avalanche Canada ghelgeson, Avalanche Canada

Summary

Confidence

Good - -1

Weather Forecast

A weakening cold front associated with the big weekend storm slides across the region Monday night persisting into Tuesday. The Kootenay Boundary region will receive light precipitation out of the system; I'm not expecting more than 5 cm by the end of the day Tuesday. A ridge of high pressure builds in Tuesday afternoon bringing dry conditions and lowering freezing levels down to valley bottom by Tuesday evening. Moderate to strong winds will be blowing out of the NW Tuesday in exposed locations. Expect a daytime high of -5 with an overnight low of -9 @ 1500m. Wednesday looks to be cool and dry with no precipitation expected.

Avalanche Summary

A size 1.5 skier accidental was reported Sunday from a thin snowpack zone where the total HS is around 100 cm. The skier triggered the avalanche on the mid December surface hoar (SH) layer. The SH was up to 15mm in size & very well preserved. All other observations were limited to sluffing in steep terrain.

Snowpack Summary

Previously gusty winds created wind slabs that can be found in wind exposed locations in both the treeline & alpine elevation bands. A thin melt/freeze crust can be found as high as 1900m & is now buried a few cm's below the surface. Compression tests have been producing sudden results on both the late December surface hoar down 35-50 cm & the mid-December surface hoar, down 70-105 cm. Test profiles and continued whoomphing suggest that avalanches associated with these persistent weakness's have the potential to propagate over large areas. Basal facets and depth hoar remain a concern in shallow rocky areas.

Problems

Wind Slabs

An icon showing Wind Slabs
Old wind slabs are lurking below ridge crests, behind terrain features, and in cross-loaded gullies.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Persistent weaknesses remain susceptible to human-triggers, including remote triggering. Be cautious of likely trigger points; areas of shallow snowpack, especially near rock outcroppings.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Jan 10th, 2012 8:00AM