Archived

Avalanche Forecast

Apr 10th, 2014–Apr 11th, 2014

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

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

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: Jasper.

Afternoon warming and solar radiation can rapidly increase the avalanche danger at all elevations.

Weather Forecast

A continued Westerly flow with snow flurries at high elevations. Daytime freezing levels will remain below treeline on Friday and Saturday. Clearing skies and sunshine are forecast for Sunday and into the new week ahead.

Snowpack Summary

At treeline (TL) and below warming temperatures are destabilizing the snowpack. Moist snow in the upper pack can be anticipated. Surface crusts will form overnight when temps drop. Solar facing slopes close to TL may have buried crusts with slab snow above. Deeply buried weaknesses near ground are a concern as are windslabs at and above TL.

Avalanche Summary

Slab avalanches observed Tuesday and Wednesday up to size 2.5 from treeline (TL) and the low alpine. All events are stepping to ground. Most are being triggered by wind loading or cornice failure. Strong SW winds are developing wind slabs. Afternoon warming and solar radiation is producing point and wet slab releases from below treeline.

Confidence

Freezing levels are uncertain on Friday

Avalanche Problems

Deep Persistent Slabs

Most observed avalanches in the past week are stepping down to this layer. Frequently observed between 2200-2400m and triggered by wind loading, cornice falls of solar exposure. Most common in shallow areas or near rock outcrops.

Avoid shallow snowpack areas where triggering is more likely.Watch for clues, like sluffing off of cliffs, that the snowpack is warming up.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Wind Slabs

Strong to extreme southerly winds continue to form slabs dating from early April. Slab activity stepping to ground quickly. Buried sun crust can present a sliding layer as seen at 2300m near Marmot. Sheltered snow can be found at treeline and below.

Use caution in lee areas. Recent wind loading have created wind slabs.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Loose Wet

Cool temperatures are suppressing this building instability. Localized sunny breaks will quickly reverse this big picture qualifier rapidly increasing the danger on the local radiated slope. Snowballing and pinwheels are good warning signs.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Be very cautious with gully features.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 2