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Avalanche Forecast

Archived

Apr 1st, 2015–Apr 2nd, 2015

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

Regions

Northwest Coastal.

A weak surface hoar layer is creating touchy conditions in some areas. If you have field observations to share, please consider using the Mountain Information Network. Click here for more info.

Confidence

Good

Weather Forecast

5-15cm of snow falling under moderate southeasterly winds is expected throughout the day Thursday with an additional 5-15 cm by Friday morning. Unsettled conditions are expected for Friday and Saturday with 5-10 cm possible each day. Daytime high freezing levels should hover around 1300 m for the forecast period.

Avalanche Summary

Reports from Tuesday include several explosive-controlled wind slab avalanches up to Size 2. In the northern part of the region numerous skier-triggered slabs up to Size 2, including wide propagations and remote triggers, have been associated with a surface hoar weak layer buried on March 25th.

Snowpack Summary

Another 10-20 cm brings recent settled storm snow totals up to 50 cm overlying a variety of old snow surfaces including surface hoar. There is some uncertainty regarding the distribution of this buried surface hoar layer, although touchy conditions are being reported in the north of the region. Strong winds have significantly redistributed the storm snow into deep wind slabs on northwest through northeast aspects.

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.