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 4th, 2022–Dec 5th, 2022

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

Regions

South Rockies, Bull, Crowsnest North, Crowsnest South, Elkford East, Elkford West.

Investigate the effect of recent strong winds on the snowpack. If triggered, wind slabs have the potential to entrain into the faceted lower snowpack, creating large avalanches.

Avoid steep, wind-loaded terrain and continually assess conditions as you travel.

Confidence

Low

Avalanche Summary

On Saturday, a few, small (size 1) skier-triggered wind slabs occurred at treeline and below treeline.

A weak layer of surface hoar continues to be a concern. Avalanches up to size 2 were last reported on this layer on November 29th, believed to fail on the surface hoar before 'stepping down' to weak and sugary facets near the base of the snowpack. Check out this MIN report for more details.

Looking forward, we expect human-triggered wind slab avalanches to remain possible at all elevation bands. These slabs have the potential to 'step down' to deeper layers, resulting in large avalanches.

We have very few eyes out there. If you do get out please consider reporting in the MIN.

Snowpack Summary

Strong southwest winds have redistributed recent snowfall into dense wind slabs in the alpine, treeline, and in exposed areas below treeline. In the alpine, many slopes may have been stripped back to early-season layers or rock. In sheltered terrain new wind-affected snow sits above more faceted (sugary, weak) snow which may not bond well. Cold temperatures have weakened and faceted the snowpack as a whole. A rain crust sits near the ground.

Total snowpack depths at treeline elevations are 50-80 cm.

Weather Summary

Sunday night

Cloudy with snowfall, trace to 3cm accumulation. Easterly wind 10-20 km/h at ridgetop. Treeline temperatures drop to -13 C.

Monday

Cloudy with snowfall, up to 5 cm of accumulation. Westerly wind 20-50 km/h at ridgetop. Treeline temperatures reach a high of -9 C.

Tuesday

Cloudy with snowfall, up to 5 cm of accumulation. Westerly wind 20-50 km/h at ridgetop. Treeline temperatures reach a high of -10 C.

Wednesday

A mix of sun and cloud. Westerly wind 30-60 km/h at ridgetop. Treeline temperatures reach a high of -5 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Keep your guard up at lower elevations. Wind slab formation has been extensive.

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.