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Avalanche Forecast

Archived

Mar 1st, 2014–Mar 2nd, 2014

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Coast.

Forecast new snow and strong winds are expected to develop a new storm slab over the next few days. The buried weak layer from early February continues to be a concern. Check out the forecasters’ blog.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain on Sunday

Weather Forecast

Overnight and Sunday: 5-10 cm of snow overnight combined with strong Southwest winds and freezing levels near valley bottoms. Another 10-20 cm of snow combined with strong Southwest winds and freezing levels rising to about 1000 metres.Monday: 5-10 cm of snow in the morning with strong Southwest winds. Some periods of broken clouds in the afternoon. Freezing levels at about 1000 metres.Tuesday: More snow and Southwest wind with freezing levels rising up to about 1500 metres.

Avalanche Summary

No new avalanche activity reported since the cold arctic air moved into the region. Deep releases on the February layer are most likely to continue from North aspects in the alpine where shaded slopes have not settled and bonded and the weak layer is well preserved.

Snowpack Summary

Cold air that moved down from the arctic has developed a melt-freeze crust on all aspects at lower elevations, and on all but Northerly aspects in the alpine. Recent very warm temperatures and periods of very strong solar radiation caused a great deal of settlement in the old storm slab above the early February weak layer. The February weak layer of crusts and facets has been reported to be rounding and bonding in areas where the old storm slab is 200 cm or deeper ( there is between 2-3 metres of snow above the weak layer in the Coquihalla area). Shallow snow pack areas where the old storm slab is closer to a metre or less continue to give sudden planar shears in snow profile tests ( there is about 60-80 cm above the weak layer in the Duffey Lake area). North aspects in the alpine may have had enough warming to settle the storm snow into a cohesive slab, but not enough to improve the weak layer bond. Big un-supported alpine North aspects are the most likely place to find a well preserved deeply buried February weak layer that may continue to allow for long propagations resulting in very large avalanches.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.