Archived

Avalanche Forecast

Apr 4th, 2016–Apr 5th, 2016

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

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

3: Considerable

The avalanche danger rating below treeline will be considerable

Regions: South Rockies.

Choose a conservative route. The spring snowpack has been very active, with large avalanches failing naturally.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Tuesday

Weather Forecast

Cloud, moderate to strong NW winds and a few snow showers may linger on Tuesday morning, before a ridge brings dry and very warm weather again for the remainder of the week. Freezing levels of around 1700 m on Tuesday are expected to climb above 3000 m by Wednesday.

Avalanche Summary

A cycle of large natural avalanches has been reported from the north Elk Valley, which occurred on Friday and Saturday. At least one of these appears to be a persistent slab, and all were likely to have been triggered by warming. A size 2.5 storm slab also released in steep rocky terrain in the south-east on Friday. With skyrocketing temperatures predicted this week, I would expect further large/deep natural avalanche activity.

Snowpack Summary

Large cornices overhang alpine slopes. Glide cracks have opened up on several slopes and herald more glide avalanches to come. Variable surface crusts exist. Low elevation and thin snowpack areas have become isothermal. Deeply buried weak layers in the mid snowpack and near the ground appear to have woken up in some areas with prolonged warming (see avalanche discussion).

Avalanche Problems

Cornices

Large fragile cornices threaten many slopes. A cornice fall could trigger a large avalanche on the slope below.

Stay well to the windward side of corniced 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: 2 - 5

Persistent Slabs

Prolonged warming has reawakened deeply buried weak layers, as well as causing glide slabs to release at the ground. The result has been some surprisingly large avalanches.

Choose conservative lines and plan to regroup out of avalanche terrain.>Avoid slopes with glide cracks.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 3 - 6

Loose Wet

With limited overnight freezing and a moisture-laden snowpack, loose wet avalanches are likely, especially on any slopes in direct sun.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3