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Avalanche Forecast

Archived

Jan 22nd, 2016–Jan 23rd, 2016

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

Regions

Sea To Sky.

A cooler and drier weekend will help reduce danger but give the new snow a day or two to settle before pushing out into bigger terrain.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Saturday: Cloudy with sunny breaks. The freezing level is around 1200-1500 m and winds are light from the W-SW. Sunday: Cloudy with sunny breaks and a chance of flurries. The freezing level is around 800-1000 m and winds are light from the S-SW. Monday: Cloudy with sunny breaks and a chance of flurries. The freezing level remains near 800-1000 m and winds rise to moderate from the S-SW.

Avalanche Summary

Observations were very limited during the storm on Thursday; however, it's very likely there was a large and widespread avalanche cycle in most areas. Some observers noted numerous natural and skier controlled slabs and loose wet slides up to size 2.

Snowpack Summary

Another 30-50 cm of new snow likely fell above 1600-1800 m on Thursday night with heavy rain saturating the snowpack below treeline. Expect dense new wind and storm slabs, and fresh cornice growth at upper elevations. Heavy loading, and the resulting avalanche cycle, may have flushed-out the mid- and early-January surface hoar/facet layers that were buried 60-100 cm deep. However, don't rule these layers out right away. It may still be possible to trigger shallow slopes that did not release naturally. The mid and lower snowpack is generally strong, with the exception of shallower snowpack areas that may be more faceted.

Problems

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.

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.