Avalanche Forecast

Issued: Mar 26th, 2012 11:09AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs, Cornices and Deep Persistent Slabs.

Avalanche Canada mpeter, Avalanche Canada

Summary

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.

Problems

Wind Slabs

An icon showing 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

An icon showing 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

An icon showing 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

Valid until: Mar 27th, 2012 9:00AM

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