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Archived

Avalanche Forecast

Mar 17th, 2017–Mar 18th, 2017
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Banff Yoho Kootenay.

Another storm on the way which will keep the danger ratings elevated through the weekend. Avoid avalanche terrain.

Weather Forecast

Another pulse of snow coming through Saturday although forecast amounts have shrunk somewhat.  Expect 20 to 30cm with moderate to strong alpine winds and freezing levels to 2000m.  This means rain will fall at lower elevations.  On Sunday precipitation will taper off with moderate alpine winds and temperatures will drop off to -15 to 18C. 

Snowpack Summary

30-60cm of recent storm snow and wind have built significant load over a fundamentally weak snowpack. The mix of previous rain, warm temperatures, and this new snow is overloading buried storm and windslabs, as well as the weak basal facet layers. Cooling Friday helped curb natural activity, but only slightly

Avalanche Summary

A flight up Hwy. 93N today showed the extent of the avalanche carnage up to size 4 on all aspects and elevations. Some fracture lines are over 1km wide. Explosive control at the ski hills and on Hwy 93 South produced large results up to size 3.5 stepping down to the deep Dec. facets or the ground showing it is still extremely sensitive out there.

Confidence

Avalanche Problems

Deep Persistent Slabs

The entire snowpack is built upon a structurally weak base, which has been overloaded by new snow and previous rain. This problem will remain touchy with the next incoming storm Saturday.
Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 3 - 4

Wind Slabs

Wind slabs over 1m deep exist at higher elevations, and in wind effected areas near treeline. This slab reacts easily to tests and continues to produce avalanches
Be aware of the potential for wide propagations.

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

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 2 - 3

Loose Wet

With freezing levels to 2000m Friday, loose, wet avalanches can't be ruled out. Steep, cliffed terrain and gullies will be likely areas.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 2