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Archived

Avalanche Forecast

Feb 28th, 2013–Mar 1st, 2013
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
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: Northwest Inland.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Synopsis: Residual moisture from the last Pacific system will give generally light amounts until Sunday, when a clearing trend develops.Friday: Most likely light snowfall (2-4 cm), but moderate snowfall possible in higher snow areas. Southwest winds 30 km/h. Freezing level around 800 m.Saturday: Light snow, 2-4 cm. Light winds. Freezing level around 600 m.Sunday: Dry and bright. Light northerly winds. Freezing level around 600 m.

Avalanche Summary

Small (size 1) soft slab avalanches could be triggered in response to ski-cutting at treeline on Wednesday; similar activity was reported on Tuesday and Monday from steep wind-loaded features. During the weekend there were reports of natural avalanches up to size 2.5 on north facing slopes following loading from new snow and wind.

Snowpack Summary

Recent storm snow amounts are 30-40 cm in the west of the region and more like 10 cm in the east. Strong southwest winds have formed touchy wind slabs in exposed terrain in the lee of ridges, gully side walls, and behind terrain features. There are a variety of old interfaces now down 60 - 100cm which include facets, crusts and isolated pockets of surface hoar. Recent observations indicate that these weaknesses have bonded fairly well now, but I still suggest digging and testing the snowpack to confirm.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow in northern and eastern parts of the region. Triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.

Avalanche Problems

Storm Slabs

Storm slabs remain in the west and the south of the region where there were deeper recent snow amounts.
Avoid steep open slopes in areas that have seen significant snow accumulations.>Assess start zones carefully and use safe travel techniques.>Note recent avalanche activity.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 5

Wind Slabs

Strong winds throughout the region have likely set up touchy wind slabs in the lee of ridges and terrain features. Watch also for growing cornices.
Avoid freshly wind loaded features.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 5