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

Dec 8th, 2019–Dec 9th, 2019

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

Regions

Glacier.

Weaknesses in the snowpack from late November could still produce very large avalanches.  Conservative use of terrain is the best way to manage this problem.

Weather Forecast

A brief ridge will give cool and relatively stable weather for the next few days.  This will be followed by another pulse of precipitation mid week.

Today: Sunny periods.  No precip. Treeline temps High -8 C. Light West winds.

Tonight: Clear periods. TL temps Low -10 C. Light West winds.

Monday: Sunny periods. TL temps High -9 C. Light west winds.

Snowpack Summary

40cm of recent storm snow (since Dec. 5th), overlies surface hoar up in sheltered locations, and is concealing evidence of the recent cycles of large to very large natural avalanches. The November 23rd surface hoar/crust/facet layer is buried 80-100+cm and remains reactive in stability tests. Tree wells are deep and deserve extra caution.

Avalanche Summary

Several large (up to size 2.5) natural avalanches were observed yesterday from steep terrain in the highway corridor.

Avalanche control Friday produced numerous size 3 and several size 3.5 avalanches.

Confidence

Due to the number of field observations

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.