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 21st, 2015–Dec 22nd, 2015

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

Regions

Purcells.

The wind effect from the last storm seems to be highly variable. The best (and safest) riding may be found on sheltered slopes at treeline and below.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

A fairly benign weather pattern is setting up for the forecast period. Light flurries are expected for Tuesday, but snowfall amounts shouldn't exceed 3cm. Isolated flurries with occasional sunny breaks are forecast for Wednesday and Thursday. Ridgetop winds are forecast to remain mainly light for all 3 days while alpine temperatures should hover between -12 and -15.

Avalanche Summary

Observations were limited on the weekend, although touchy wind slab avalanches to 20cm in depth were being triggered near ridgetop in response to new snow and wind in the north of the region. I'd anticipate the possibility of human-triggered wind slab avalanche activity over the next few days.

Snowpack Summary

Throughout last weekend there was up to 20cm of new snow. Strong southerly winds have redistributed much of this snow into deeper wind slabs in exposed lee features in the alpine and at treeline. Between 40 and 80cm below the surface you'll likely find a layer of weak buried surface hoar which is most prominent between 1400m and 1800m although it may extend higher in the mountains south of Invermere. Snow pit tests suggest that human triggering of this interface is becoming unlikely, although a release at this interface could be destructive in nature.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.