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Archived

Avalanche Forecast

Mar 26th, 2012–Mar 27th, 2012
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: South Coast.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Tuesday: Expect an unsettled day with flurries and southerly winds increasing from light to moderate. Freezing levels could reach 1500m with maximum accumulations of 5cm. Wednesday / Thursday: Continued unsettled under a slight cooling trend. Total accumulations could reach 15cm with consistent moderate southerly winds and freezing levels reaching 800m each afternoon.

Avalanche Summary

Loose wet avalanches up to size 2.0 triggered by daytime heating have been reported, as well as isolated cornice releases to size 2.5. The warm weather has increased the glide crack activity with new cracks opening in the Coquihalla area but not actually failing.

Snowpack Summary

The recent warm, clear weather has left us with an aggressive melt freeze crust on solar aspects well into the alpine while shady, dead north slopes have grown some small surface hoar and remain powdery. Cornices loom in the alpine. Recent storm snow (before the warmup) is bonding well, with occasional windslabs lurking in immediate lee locations. Crusts down around 60cm can be found on solar aspects in the Duffey Lake, Chilcotin, and down closer to 100cm in the Coquihalla. Deep, persistent weak layers buried in early February are variable in distribution across the region but remain a key concern. In recent snowpack analysis this layer remains well preserved as surface hoar on north aspects and is a suncrust, facet combo on solar aspects. On both aspects we have reports of clean sudden planar shears at an average depth of 150cm. Although the likelihood of triggering this layer has decreased, the potential for surprisingly large avalanches remains.

Avalanche Problems

Wind Slabs

New windslabs will form with the new snow and increased wind. Some interesting thin slabs have formed from downflowing wind associated with the warm weekend.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Cornices

Large cornices loom at ridgecrest and will grow under the current conditions. They may act as a large trigger to deeper weaknesses.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 6

Deep Persistent Slabs

Persistent weaknesses, buried in February, still have the potential to create very large, destructive avalanches if triggered. Possible triggering mechanisms include a person/sled on a thin snowpack spot, cornice fall, or step-down avalanche.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 4 - 8