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 15th, 2020–Jan 16th, 2020

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

Regions

Kootenay Boundary.

An increasing trend of large persistent slab avalanches is a growing concern in the region. Choose terrain with the expectation that a smaller storm slab could trigger a deeper weak layer in the snowpack. 

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

Wednesday night: Cloudy with increasing flurries bringing 10-15 cm of new snow. Moderate to strong southeast winds.

Thursday: Cloudy with continuing flurries bringing 10-20 cm of new snow. Moderate to strong south winds easing over the day. Alpine temperatures around -8.

Friday: Broken cloud cover. Light southwest winds. Alpine temperatures around -11.

Saturday: Cloudy with scattered flurries bringing about 5 cm of new snow. Light to moderate south winds. Alpine high temperatures around -7.

Avalanche Summary

This region has been a hot spot for recent avalanche activity. A number of large natural avalanches up to size 3 were reported on east, southeast and south facing slopes above 2000 m in the Rossland area Monday with crowns up to 100-150 cm in depth.

In the rest of the region both natural and explosive controlled avalanches up to size 2.5 were observed on all aspects above 1800 m. Many avalanches failed on the December 27th Surface Hoar and one avalanche on a north/northeast facing slope at 1800 m involved the mid November facets.

On Sunday the bulk of the avalanche activity was limited to loose dry avalanches but a spooky avalanche was remote triggered by a group of skiers, more details and photos in this MIN report.

Snowpack Summary

The storm of the last several days brought 20 to 50 cm of snow which fell with moderate to strong southwest wind before winds switched to the north/northeast Sunday night. 

The resulting wind fueled storm slabs likely remain sensitive to human triggers, particularly in exposed lee terrain features. More recent snow might hide slabs and make it trickier to navigate around them.

Deeper in the snowpack, a few layers of weak and feathery surface hoar may still be found around 70 to 130 cm deep which have been active as recently as Monday.

The base of the snowpack is also weak in parts of the region where it consists of sugary faceted snow around a melt-freeze crust.

Terrain and Travel

  • Avoid freshly wind loaded terrain features.
  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Be aware of the potential for large avalanches due to the presence of buried weak layers.

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.