Archived

Avalanche Forecast

Mar 14th, 2015–Mar 15th, 2015

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Forecast snow and wind are expected to increase the avalanche danger. Be prepared for winter conditions at higher elevations.

Confidence

Poor - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

The first wave of precipitation and strong southwest winds is expected to end Saturday evening, and there should be a short break before the next wave starts on Sunday morning. The freezing level should gradually drop on Sunday, with most of the forecast 10-15 mm of precipitation coming as snow above 1200 metres combined with moderate southwest winds. Snow/rain should end late Monday morning or early afternoon, but remain cloudy. Mostly cloudy with a chance of sunny periods on Tuesday as the freezing level rises to about 2000 metres.

Avalanche Summary

No new avalanches reported. I suspect wet conditions with poor visibility have limited observations. Heavy precipitation in the south of the region may have resulted in loose wet and wet slab avalanches in areas that have not had a re-freeze for several days.

Snowpack Summary

Rain up to at least 2000 metres on Saturday may increase the likelihood of triggering a wet slab avalanche on one of the buried persistent weak layers. Strong southwest winds combined with new snow at higher alpine elevations may have developed new wind slabs that are easy to trigger, and may allow for long propagations where they are sitting on a crust/facet combination. In many areas, the snowpack is becoming moist and slowly turning into a more uniform, springtime snowpack. The surface has only seen limited refreezing these last few days. The most prominent feature in the snowpack is the thick late-February crust, down 5-20 cm. Limited reports suggest this crust is breaking down in some areas, while it remains supportive all the way to ridge crest in other spots. There are still weak layers below this crust. It is unclear whether these deeper layers are still reactive, but I would go with caution in case they are.

Avalanche Problems

Wet Slabs

Several days without a re-freeze combined with heavy rain up to at least 2000 metres may result in loose wet avalanches releasing in steep terrain, and wet slab avalanches stepping down to buried weak layers resulting in large avalanches.

Avoid steep or committing slopes if the snow is moist or wet.>Avoid avalanche terrain during periods of rain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Wind Slabs

New snow and strong winds have created new windslabs at higher alpine elevations where the freezing level dropped enough for snow to accumulate.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 3