Avalanche Forecast

Issued: Feb 15th, 2015 3:00PM

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

mike.koppang, Alberta Parks

Kananaskis.

The SPAW issued by Kananaskis and the National parks has now been extended to Tuesday. See www.albertaparks.ca or here for details.

Summary

Confidence

Good

Weather Forecast

Temperatures will be cooling over the next few days to more seasonal values. Freezing levels will remain at lower elevation until wednesday when they are again forecast to climb up to 1800m. The sun is gonna be in and out over the next while and it seemd to pack a punch in terms of solar radiation so keep an eye on overhead slopes that may be in the sun.

Avalanche Summary

A skier accidental sz 2.5 avalanche occurred late in the day on Saturday. The slide occurred on an E aspect at 2400m, was 130m wide, up to 100cm deep and ran over 600m. 5 skiers were involved and one fatality resulted. Yesterday several sz 2-3 avalanches were observed when the sun came out. Some of the fracture lines were over 500m wide failing at what appeared to be the jan 31st interface down 50-90cm and some avalanches also stepped down to ground.

Snowpack Summary

A temperature crust from the recent heat can be found on all aspects up to 2200m then only on solar aspects up to 2400m. Easy to moderate sheers persist within the upper snowpack down 30-40cm. Extended column tests also indicate that this layer is prone to wide propagations. The Jan 31st interface is down 70-80cm but the bond at this interface seems to be improving. The basal layers in the snowpack area still weak and any avalanche that is triggerred will likely step down to these basal layers. Temperatures are cooling and freezing the previous isothermal snowpack at lower elevations.

Problems

Wind Slabs

Skier triggerrable windslabs are being observed in alpine areas as well as gullied and crossloaded features at treeline.

Choose well supported terrain without convexities.>Dig down to find and test weak layers before committing to a line.>Resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Deep Persistent Slabs

Avalanches in the upper snowpack will likely step down to a deeper layer such as the Jan 30th or the Nov 6th or the weak basal facets.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Be wary of slopes that did not previously avalanche>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 6

Cornices

Cornices have grown over the past week and many large avalanches have been triggerred by cornice collapses.

Avoid steep slopes below cornices.>Cornices become weak with daytime heating. >

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Feb 16th, 2015 2:00PM