Archived

Avalanche Forecast

Mar 13th, 2015–Mar 14th, 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

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

Weather models are having trouble with the specifics of this weekend's weather. Any time it is raining, snowing or blowing, assume elevated avalanche danger.

Confidence

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

Weather Forecast

Two pulses of precipitation are expected this weekend. The first, on Saturday, brings around 15-20 mm rain with strong SW winds and a freezing level near 2200 m (snow is possible up high). Late on Sunday and into Monday, it looks more hopeful for snow (5-15 cm) with the freezing level closer to 1500 m. However, the system on Sunday may move to the south and miss us. Winds switch briefly to the NW before swinging back to the SW. Weather models are not handling the developing situation well, so I have little confidence in the specifics of the weather forecast.

Avalanche Summary

Apart from small loose wet sluffs triggered by skiers on steep sunny slopes, no new avalanches have been reported in the past several days. Rain, snow and strong winds are expected to drive some avalanche activity this weekend.

Snowpack Summary

Rain on Saturday is likely to further weaken already moist snow. Wind slabs may be found at high elevations. 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

Loose Wet

Rain may weaken an already moist snowpack, causing loose wet or wet slab avalanches in steep terrain.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Cornices become weak with heating, so avoid exposing yourself to them.>Avoid steep or committing slopes if the snow is moist or wet.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 3

Wind Slabs

Wind slabs may be found at the highest elevations, near ridge tops.

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

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 3