Archived

Avalanche Forecast

Feb 11th, 2015–Feb 12th, 2015

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

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

1: Low

The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

There is low confidence in the strength of the warm snowpack at all elevations.

Confidence

Fair - Due to the number of field observations

Weather Forecast

Warm temperatures with light precipitation possible for the forecast period. Freezing levels could rise above 3000 m on Friday, before dropping back down on Saturday. Alpine winds are expected to me moderate southwesterlies on Thursday and Friday, before picking up and switching to northwesterlies throughout the day on Saturday.

Avalanche Summary

Reports from Tuesday include evidence of old natural slab avalanches up to Size 2.5. Heavy triggers such as explosives and snowcats were able to trigger 20-90 cm deep storm slabs up to Size 2, but no new naturals were observed and ski-cutting was ineffective.

Snowpack Summary

The rain line during recent heavy precipitation generally hovered around 1700m, although there were periods where rain fell into the alpine. Above that elevation, heavy accumulations of moist, dense snow have been pushed by strong southwest winds into cornices and deeper deposits on the lee side of ridgecrests and terrain breaks. Recent storm snow is poorly bonded to a hard crust, which may have overlying surface hoar, that was buried late January. The mid-December crust/facet/surface hoar weakness may be persisting in the mid to lower snowpack at higher elevations.

Avalanche Problems

Storm Slabs

Deep unstable storm slabs may linger at higher elevations. As you head into the alpine in search of drier snow, be wary of steeper slopes that haven't avalanched as very large avalanches are a concern.

Be cautious as you transition into wind affected terrain.>Good day to make conservative terrain choices.>Be alert to conditions that change with elevation.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 5

Persistent Slabs

A deeply buried week layer which formed in December should still be treated with suspicion. Although not much is known about the current reactivity of this potentially destructive layer, I'd use extra caution in steep, unsupported alpine terrain.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar or crust/facet layer.>Choose well supported terrain without convexities.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6

Loose Wet

Pushy loose wet and wet slab avalanches remain a concern at lower elevations where rain has saturated the snowpack. Pay close attention to daytime temperatures, and whether snow surfaces are moist or refrozen.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >Avoid exposure to gullies and terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3