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

Feb 19th, 2023–Feb 20th, 2023

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

Regions

Banff Yoho Kootenay, Little Yoho, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

Snowfall and wind for the next 48 hours will hold the danger rating at HIGH in the alpine. The deep slab problem could finally have enough load with the incoming snow to start producing avalanches that run full path.

Confidence

Moderate

Avalanche Summary

No significant avalanches were observed or reported on Sunday. However, numerous avalanches up to size 3 were reported in the past 5 days, previous to the recent storm snow and wind. With the recent weather inputs, forecasters expect there to be a substantial cycle Mon and Tues.

Snowpack Summary

15 to 35 cm of storm snow over the past 72hrs with moderate to strong SW-W winds have created extensive wind effect in the alpine and contributed to wind slab development. Several persistent weak layers exist 35-65cm below the surface. These weak layers include crusts, facets and surface hoar buried in January and are producing sudden test results in some locations. Deeper in the snowpack, the November crust/facet layer is found about 40 cm above the ground and also continues to produce sudden test results.

Weather Summary

Snowfall up to 20cm is expected Monday late afternoon and into the next day. The wind will remain elevated in the 60-80km/hr range from the West until late in the day Monday. After the regime of wind and snow temps will dive as an arctic air mass settles midday Tuesday.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Make conservative terrain choices and avoid overhead hazard.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Cornice failure may trigger large avalanches.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.