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Avalanche Forecast

Jan 26th, 2013–Jan 27th, 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
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
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: Purcells.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Next active system (aka fresh snow?) not until Monday; likely to have lots of wind with it. Tuesday may be cold and dry (if you're under the arctic air) or warmer with more snow (if you're south of the arctic front).Overnight & Sunday: WIND becoming NW light to moderate, TEMPERATURE -5 to -10 C near treeline with freezing level to 900m possible, PRECIPITATION traces of new snow possible.Monday: WIND NW moderate to strong, PRECIP 10 to 15 cm late in the day, TEMP -10 C but freezing level could climb again to 900m ahead of the cold frontTuesday: colder with -15 near treeline, light wind, and flurries.

Avalanche Summary

Mostly small loose avalanches (sluffs) up to 1.5 reported. The little bit of explosive testing had limited results to size 2I'd be watching for the recent storm snow settling into a slab on the sun crust or surface hoar... and for wind building bigger pillows behind ridges and in cross-loaded gulleys.

Snowpack Summary

Storm snow amounts over the past few days are 30 to 40 cm with as much as 60cm reported. On Friday this snow remained mostly loose and powdery except for pockets of windslab behind ridges and ribs. On Saturday (&Sunday) look for this storm to be settling into more of a slab, and the wind could be building additional pillows of windslab. Below the new snow is a suncrust on steep southerly facing slopes and a surface hoar layer at treeline and lower elevations (but it has a patchy distribution). Early January surface hoar is now around 60 - 80 cm deep and is also patchy but may extend into the alpine.

Avalanche Problems

Storm Slabs

Watch for recent storm snow settling into a slab over a sun crust on steep southerly facing slopes or over surface hoar on shady wind protected glades. Also, pillows of windslabs likely in pockets behind ridges and cross-loaded gulleys.
Assess start zones carefully and use safe travel techniques.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 3

Persistent Slabs

Watch steep southerly facing slopes (buried suncrust) and shady sheltered glades (buried surface hoar)
Caution around open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4