Avalanche Forecast

Issued: Mar 6th, 2019 3:47PM

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

mconlan, Avalanche Canada

Kootenay Boundary.

Variable snowfall amounts are expected across the region by Thursday, from 10 to 20 cm. The persistent slab problem still exists and is best controlled by diligent group management.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

WEDNESDAY NIGHT: Cloudy with snowfall, accumulation 5 to 15 cm, light to moderate southwest wind, alpine temperature -6 C.THURSDAY: Cloudy with light snowfall, accumulation 2 to 5 cm, moderate southwest wind, alpine temperature -11 C.FRIDAY: Cloudy with light snowfall, accumulation 1 to 3 cm, light to moderate west wind, alpine temperature -11 C.SATURDAY: Cloudy with isolated snowfall, trace accumulation, light northwest wind, alpine temperature -10 C.

Avalanche Summary

Small sluffing was observed in steep terrain on Tuesday. Otherwise, no new avalanches were observed.

Snowpack Summary

Around 10 to 20 cm of new snow is expected to fall Wednesday night into Thursday. This snow will fall on a wind-affected snow surface in exposed terrain, soft and faceted snow in sheltered areas, and a melt-freeze crust on southerly aspects.Two layers of weak and feathery surface hoar crystals are buried in the snowpack between 40 and 80 cm deep, which were buried mid-February and early-February. The layers may be associated with a melt-freeze crust on southerly aspects. These layers remain reactive in snowpack tests and have produced sporadic avalanches in the region over the past week.

Problems

Storm Slabs

New snow Wednesday night into Thursday may not bond well to the previous surfaces. The snow may be reactive to human traffic in areas where enough snow accumulates.

Use caution in freshly wind-loaded features, especially near ridge crests and in steep terrain.Recent new snow may be hiding wind slabs that were easily visible before the snow fell.Assess the bonding of the new snow with underlying layers as you travel.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Two layers of weak surface hoar and/or a crust are buried 40 to 80 cm. These layers have recently been the most active between 1700 m and 2200 m and on southwest to southeast aspects. The problem is best controlled with appropriate group management.

Apply caution around sheltered and open areas at treeline and below. Space out to limit exposure.Choose moderate-angled terrain with low consequence, avoiding terrain traps.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Valid until: Mar 7th, 2019 2:00PM