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Archived

Avalanche Forecast

Feb 10th, 2015–Feb 11th, 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
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

What will all the forecast warming do to the snowpack? I'm honestly not sure. With this much uncertainty sticking to conservative terrain may be the only reasonable course of action.

Confidence

Poor - Due to the number of field observations

Weather Forecast

The big story for the next few days is the freezing level which should be on the rise throughout the period. Wednesday: Freezing level around 1800m, no precipitation, Light variable winds at all elevations. Thursday: Freezing level starts near 1800m, rising to around 2500m by the afternoon. Winds light at treeline, strong west at upper elevations. No precipitation. Friday: Freezing should be hovering around 3000m all day. Light winds at treeline, moderate SW winds at ridgetop. No precipitation.

Avalanche Summary

Observations have been essentially non-existent in recent days. This likely speaks more to a lack of observers rather than actual conditions. I'm confident recent storm loading has produced large storm slab avalanches at higher elevations, while loose wet or wet slab avalanche activity occurred at lower elevations where rain fell.

Snowpack Summary

Since February 5th, moderate to heavy precipitation fell throughout the region. The rain line during the storms generally hovered around 1700m, although there were periods where rain fell into the alpine. In the alpine, heavy accumulations of moist, dense snow have been pushed by strong southwest winds into much deeper deposits in upper elevation lee terrain. The recent storm snow overlies a hard crust layer (which may have overlying surface hoar) which was formed in late January. At lower elevations, continuous rain has saturated the snowpack. I suspect cornices are large and fragile.In the mid to lower snowpack, you may find the mid-December crust/facet/surface hoar combo. At lower elevations rain has likely destroyed what was left of this layer. At higher elevations recent storm loading may have produced very large avalanches at this interface, although observations have been extremely limited.

Avalanche Problems

Storm Slabs

At higher elevations deep and destructive storm slabs overlie a weak crust/ surface hoar interface. Very large avalanches may still be possible under light loads, especially with forecast warming and possible solar radiation later in the week.
The new snow will require several days to settle and stabilize.>Be alert to conditions that change with elevation.>Good day to make conservative terrain choices.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 5

Persistent Slabs

Buried persistent weak layers in the mid snowpack have been over-loaded by the new storm snow. Very large and destructive avalanches have occurred under light loads, and conservative terrain selection remains critical.
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Choose well supported terrain without convexities.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar or crust/facet layer.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3