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Archived

Avalanche Forecast

Jan 19th, 2013–Jan 20th, 2013
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: South Rockies.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Sunday: Inversion. Freezing level at valley bottom. Potential for another above freezing layer to develop in the afternoon from 1500m – 2200m. Ridgetop winds Strong NW. Treeline winds moderate NW. Isolated flurries, no significant accumulations.Monday:  Inversion. Freezing level at valley bottom. Above freezing layer from 1500m – 2200m. Ridgetop winds Strong NW. Treeline winds light W. No precipTuesday: Freezing level should stick around valley bottom all day. Ridgetop winds Strong W, switching to extreme SW as ridge flattens in the afternoon. Treeline winds Mod to strong SW. No precip

Avalanche Summary

Loose snow avalanches continued Friday driven by strong SW winds. Activity was greatest on steep solar aspects which produced loose snow avalanches to size 1.5.  We received a couple of different reports of skiers intentionally triggering size 1 avalanches in cross loaded gulley features.

Snowpack Summary

Intense recent winds have redistributed snow and created large cornices. The snow surface is now a mix of sastrugi, hard slab and soft slab in open areas.  With the warm temps, slopes receiving direct sun are moistening in the afternoon.  Surface hoar is continuing to form in protected areas too. Below this around 60cm of settled snow rests on a myriad of old surfaces (January 4th interface) that include sun crust on steep south and west facing terrain, surface hoar in sheltered locations at treeline and below and facets everywhere else. Reports indicate that this bond has strengthened over time and is now fairly tight. The overlying slab has also settled significantly. The bond at this interface seems to have strengthened somewhat with time. The overlying slab has also settled significantly.  There are some reports of glide cracks on Mt Fernie, these mysterious phenomena should be given a wide berth.

Avalanche Problems

Wind Slabs

Big winds out of the NW, W and most recently SW wreaked havoc on the region. I suspect most of the slabs have grown old and tired, but you may find the odd sensitive one lurking near ridge crest or immediately lee of a mid slope feature like a rib.
Be cautious as you transition into wind affected terrain.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>

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

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1 - 4

Persistent Slabs

While unlikely, slopes that didn't slide in the last avalanche cycle may still be of concern this weekend. Triggering is most likely in areas that go from thick to thin in steep unsupported terrain.
Conditions are greatly improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1 - 5