Avalanche Forecast

Issued: Apr 11th, 2014 5:01PM

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

a.l. horton, Parks Canada

Jasper.

Avalanche control on the Icefields Parkway is possible this Monday as warm temperatures and sunny skies will destabilize the snowpack treeline and below.....stay tuned!

Summary

Weather Forecast

Cool temps overnight will continue through the day Saturday.Â Snow flurries will begin tonight but skies will clear by tomorrow afternoon.Â Another cold night expected Saturday then the sun will come out and temperatures will rebound on Sunday and Monday.

Snowpack Summary

At treeline (TL) and below, warming temperatures have destabilized the snowpack with moist snow in the upper pack. 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

A couple of slab avalanches to size 2.5 treeline to alpine have occurred in the past 48 hrs.Â A large alpine cornice failure on an E aspect slope had limited propagation.Â Afternoon warming and solar radiation has produced point and wet slab releases from below treeline.

Confidence

Timing or intensity of solar radiation is uncertain on Saturday

Problems

Deep Persistent Slabs

Most observed avalanches in the past week have stepped down to this layer. Triggers include: wind loading, cornice fall and solar exposure. Most commonly triggered from shallow areas or near rock outcrops.

Avoid shallow snowpack areas where triggering is more likely.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Wind Slabs

Gusty moderate SW winds continue to form slabs dating from early April. Sheltered snow does exist at treeline and below.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

A melt freeze crust will form overnight however it will deteriorate rapidly with prolonged solar exposure.

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

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Apr 12th, 2014 4:00PM