Avalanche Forecast

Issued: Apr 3rd, 2016 9:35AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs, Cornices and Loose Wet.

pgoddard, Avalanche Canada

Kootenay Boundary.

The danger ratings assume around 10 cm new snow. If there is more new snow, bump up the danger ratings!

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Monday

Weather Forecast

A front passing through on Monday is expected to bring around 10 mm (up to 25 mm at Kootenay Pass is possible) precipitation and moderate to strong SW winds (switching to NW post-front), with the freezing level falling from around 2500 m to 1500 m. Cloud and a few snow showers may linger on Tuesday morning, before a ridge brings dry and very warm weather again.

Avalanche Summary

A natural cycle of size 1-2 loose wet avalanches continued though the week and into Saturday. On Friday, an explosives control mission near Nelson produced several size 2-3 wet slab avalanches. Warming-related avalanche activity should ease with the passage of a cold front on Monday.

Snowpack Summary

Large cornices overhang alpine slopes and threaten to trigger avalanches on slopes below. New snow will be landing on mainly moist or crusty snow surfaces. At low elevations, the snowpack is isothermal. The late February surface hoar/ crust interface (down 80 to 130 cm) remains a low probability/ high consequence concern. Test results are variable, with occasional sudden planar (pop) results. While generally unlikely to trigger, this layer could produce surprisingly large avalanches with a cornice fall or warm temperatures.

Problems

Storm Slabs

New snow and variable winds may build new storm slabs.

Choose well supported terrain without convexities.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

Large fragile cornices threaten many slopes. A cornice fall could wake up a persistent weak layer and trigger a large avalanche on the slope below.

Give cornices a wide berth when travelling on ridges.>Do not travel on slopes that are exposed to cornices overhead.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Loose Wet

Rain on snow may lead to loose wet avalanches, especially at low elevations.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Apr 4th, 2016 2:00PM