Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Jan 10th, 2018–Jan 11th, 2018

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.

Regions

North Columbia.

Avalanche activity has been at a steady peak and touchy conditions will persist.  Travel in avalanche terrain is not recommended.

Confidence

High -

Weather Forecast

Thursday: Mainly cloudy with isolated flurries and a trace of new snow. Light southeast winds. Alpine high temperatures to -11.Friday: A mix of sun and cloud. Light southwest winds. Alpine high temperatures to -9.Saturday: Mainly cloudy with isolated flurries and a trace of new snow.. Light to moderate west winds. Alpine high temperatures to -2.

Avalanche Summary

Reports from Tuesday suggest a high point in a natural avalanche cycle on both the January 5 surface hoar layer as well as the December 15 surface hoar layer. Avalanche activity on these interfaces was extensive, with natural and remote (from a distance) triggers forming a large percentage of observations. Sizes ranged from Size 1-3, with slab depths ranging from 30-80 cm, and activity was observed on all aspects and elevation ranges. Reports from the previous two days showed similar activity.Looking forward, incremental loading from new snow on Thursday is likely to keep the region in an active pattern of avalanche activity that may intensify toward the weekend with forecast clearing and warming.Please share your recent observations through the Mountain Information Network (MIN).

Snowpack Summary

Recent storms have brought 40-60 cm of new snow to the region. The new snow sits on surface hoar on sheltered slopes as well as sun crust on steep solar aspects. Numerous storm slab avalanches resulted as the new snow formed a slab before bonding to the surface. Moderate to strong southwest winds accompanied the snowfall at higher elevations, creating wind slabs in lee features.As the new snow continues to consolidate, it is forming a dangerous slab above several persistent weak layers that exist in the snowpack. The first of these is the surface hoar that exists at the new snow interface. Recent snowpack tests and avalanche activity show a high degree of reactivity at this layer. Below it, the December 15 surface hoar is now buried 50 to 100 cm deep. This layer has been the failure plane in many recent destructive slab avalanches. Its reactivity has been most apparent at treeline and below treeline. Deeper in the snowpack at depths of about 90 to 150 cm, a rain crust from November is producing variable snowpack test results, from sudden fractures to no result. This layer is considered dormant but could be triggered in thin spots around variable snowpack areas in the alpine.

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.