Avalanche Forecast

Issued: Feb 17th, 2016 7:13AM

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

Alberta Parks mike.koppang, Alberta Parks

Solar radiation has lots of punch these days so when the sun does come out, stability will quickly deteriorate. Freezing levels on Thursday are forecast to be around 2100m.

Summary

Confidence

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

Weather Forecast

Cloudy with scattered flurries.Accumulation: 4 cm.Alpine temperature: High 0 °C.Ridge wind west: 30 km/h gusting to 85 km/h.Freezing level: 2100 metres.

Avalanche Summary

One new avalanche was observed today on an E aspect on Mt Murray.  A sz 1 that was 80-100cm deep, about 50m wide and ran for around 150m.  We suspect that a cornice collapse was the trigger.

Snowpack Summary

The alpine snow pack is complex due to variable wind direction and new snow over the past few days. Forecasters are not confident  about stability in the alpine due to the variability of the snow depths.  The concern is regarding triggering from a thin areas and wide propagations resulting in large avalanches. Some good skiing is found below 2300 meters in the trees although at lower elevations the snow pack is faceted and un supportive.  Two main layers are important to note in the snowpack at this time.  The Feb 11th interface down 30-50cm is producing moderate sheers but the quality of these sheers varies depending on aspect and weak layer, crust vs facets.  The Jan 6th layer is down deeper 60-80cm and is producing more hard sheers but its likely that any avalanche initiating in the upper snowpack will step down to this interface.  Dig down and evaluate these interfaces before committing to a feature.

Problems

Wind Slabs

An icon showing Wind Slabs
Use caution on steeper and unsupported slopes.  Easy-moderate sheers were being encountered on solar aspects where the recent snow is overlying a strong temperature crust.
Caution in lee and cross-loaded terrain near ridge crests.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 4

Persistent Slabs

An icon showing Persistent Slabs
This interface is gaining strength but keep it in your mind as you travel.  A few avalanches over the past 72hrs were observed on this interface.
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>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 - 5

Valid until: Feb 18th, 2016 2:00PM