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Archived

Avalanche Forecast

Mar 12th, 2017–Mar 13th, 2017
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Kananaskis.

Another large sz 3 in commonly skied terrain was observed on Sunday.  See photo. Be aware of large events in the Alpine running full path to the end of their historical runout.

Confidence

High -

Weather Forecast

Over the next few days we can expect a mix of sun and cloud, some light convective flurries and moderate winds out of the SW.  When the sun does come out these days it has lots of "punch" and crusts are now being observed on solar aspects. 

Avalanche Summary

A sz 3 avalanche was observed on Tent bowl here on Sunday.  The avalanche was 240m wide with an average depth of 1m and up to 2m in places failing on the ground. It ran down into mature timber and logged a large amount of new trees.  This took out a commonly skied area.  There were also 3 Cornice collapses observed on Mt Rundle all resulting in sz 2-2.5 Avalanches that were running to mid path.

Snowpack Summary

Windslabs are being encountered in Alpine areas and in isolated areas such as steep crossloaded gullies at treeline.  The biggest concern is the weak basal layers that exist throuhgout the region.  These layers just simply cannot be trusted and all larger features should just be avoided until we go through a few solid melt freeze cycles.  Thin melt freeze crusts are being found on Solar aspects up to 2400m. 

Avalanche Problems

Wind Slabs

There are multiple layers of windslabs out there at this time.  Recognize that it is possible for a small surface slab to start a chain reaction that could go all the way to the bottom of the snowpack as we saw on Tent ridge on Sunday.
Caution in lee and cross-loaded terrain near ridge crests.Minimize exposure to overhead hazard from cornices.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Deep Persistent Slabs

Similar to the windslab problem, these deeper layers consist of many weak layers being lumped together into a single problem. The take home point is the fact that they are near the bottom of the snowpack and any avalanche involving them will be big!
Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4

Cornices

Cornice collapses are triggering slabs up to sz 3.5 on underlying slopes waking up the basal layers.
Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.Extra caution needed around cornices with current conditions.

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

Elevations: Alpine.

Likelihood: Likely

Expected Size: 2 - 4