Avalanche Forecast

Issued: Mar 2nd, 2012 8:44AM

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

ghelgeson, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Good

Weather Forecast

An "almost pineapple" weather pattern is setup across the province, and while the neighboring regions to the north receive the full brunt of the firehouse, the jet is tracking north of the Kootenay Boundary. SAT: Freezing Levels (FZLVL) quickly climb to 1800 m early in the day Saturday. Expect snow above this elevation and rain below it. 5.9mm SWE expected. 2km Winds: Mod/Strong W. SAT NIGHT: FZLVL stays high overnight, near 1800m SUN: FZLVL stays near 1800m, all day. 10mm SWE expected. 2km Winds Mod SW. MON: FRLVL slowly lowers throughout the day. 5mm SWE forecast. Winds initially Strong SW Tapering to Light W late in the day.

Avalanche Summary

A few noteworthy avalanches from yesterday. A sled group triggered a size 2.5 below treeline near 1700m in a moderately angled cutblock. Reports indicate a full burial. In the Nelson backcounty a snowboarder triggered a size 2.5 avalanche BTL, 100cm in depth, 200m wide, running full path to the valley bottom. Boarder was able to cut out of the slide and was unharmed. Steep sluffing continued to be an issue at all elevations in steep terrain.

Snowpack Summary

15-35cm of new snow is sitting on surface hoar on shady aspects and a thin sun crust on south aspects. A weak storm snow interface of well-preserved stellars is down approximately 40-50cm and reactive to human triggers on steep shady (cold) slopes at and below treeline. However the main snowpack feature of concern continues to be the surface hoar buried mid-February, which is now down 60-120cm and still giving easy sudden snowpack test results. This persistent weakness is susceptible to remote triggering and has the ability to propagate in low angled terrain, and the overlying slab structure creates the potential for step-down avalanches. Although generally getting deeper and harder to trigger, avalanche professionals throughout the region continue to treat this weakness with extreme caution.

Problems

Wind Slabs

Generally lurking below ridgecrests, behind terrain breaks, and in gullies. Wind slabs are very touchy and continued strong winds over the forecast period is expected to overload weaknesses.

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

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 5

Storm Slabs

Touchy weaknesses within and under the recent storm snow are expected to become more reactive with warm temperatures and new snow load.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

Persistently weak buried surface hoar demands continued diligence and conservative decisions. The potential for remote triggering, step down avalanches, and wide propagations, makes this weakness particularly tricky to predict.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 6

Valid until: Mar 3rd, 2012 8:00AM