Avalanche Forecast

Archived

Mar 2nd, 2012–Mar 3rd, 2012

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

Kootenay Boundary.

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

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.