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Archived

Avalanche Forecast

Feb 7th, 2016–Feb 8th, 2016
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
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
3: Considerable
The avalanche danger rating below treeline will be considerable
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

We're dealing with a complex snow pack and a significant warming trend. Solar radiation will drive the avalanche conditions for the next couple of days. Use extra caution if you see signs that the sun is starting to warm up the snow.

Confidence

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

Weather Forecast

No precipitation is expected for the forecast period. A strong temperature inversion will develop overnight on Sunday with an  above freezing layer forming in the alpine as warm air overrides cool air trapped in the valleys. Valley cloud will linger although there is some uncertainty as to how high it will reach. MONDAY: mainly sunny in the alpine, a freezing level rising to 3500m,and moderate westerly winds. TUESDAY: sunny in the alpine, a freezing level of 3500m, and moderate south westerly winds. WEDNESDAY: sunny with scattered clouds, a freezing level of 2800m, and moderate westerly winds.

Avalanche Summary

Widespread natural avalanche activity, up to size 2, mainly on east through northwest aspects was reported from across the region on Sunday. Wind slabs remain reactive to ski cutting at treeline and alpine elevations. Near Rosland, two size 1.5, skier triggered avalanches have been reported in the last couple of days, releasing between 1800m and 1900m on the late January surface hoar.

Snowpack Summary

Up to 25cm of new snow fell through the weekend and is settling rapidly. Moderate to strong southwest winds have scoured windward slopes and formed stiff wind slabs at treeline and in the alpine. These slabs are still sensitive to human triggering. Around Rossland, the new snow is sitting on a layer of surface hoar down 40cm that is reported to be widespread at treeline elevations. A rain crust can be found in most other parts of the region at this depth. Below this, a thick slab rests on a layer of surface hoar that was buried earlier in January and is now down 80-130 cm. This layer remains a concern in at and bellow treeline, producing sudden planar fractures in snowpack tests under moderate to heavy loads.

Avalanche Problems

Wind Slabs

Warming could increase the sensitivity of wind slabs and will weaken cornices. If the upper snowpack becomes moist, both loose and slab avalanches are more likely to gain significant mass as they run.
Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Persistent Slabs

Avalanches on this layer are unlikely but would have disastrous consequences.
Be aware of the potential for large avalanches due to the presence of buried surface hoar. >Avoid open slopes at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 5