Avalanche Forecast

Issued: Apr 10th, 2014 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is low. Known problems include Deep Persistent Slabs, Wind Slabs and Loose Wet.

rupert wedgwood, Parks Canada

Jasper.

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

Summary

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

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

Valid until: Apr 11th, 2014 4:00PM