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 5th, 2023–Feb 6th, 2023

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

Regions

North Rockies, Kakwa, McGregor, Pine Pass.

With additional snow arriving Monday afternoon, we expect dangerous avalanche conditions to persist. Human-triggered avalanches are likely on steep slopes and natural avalanches will likely continue on wind-loaded slopes. Storm slab avalanches could step down to the facets near the base of the snowpack, producing very large avalanches.

Confidence

Moderate

Avalanche Summary

In the Pine Pass area, heavy snowfall caused a natural avalanche cycle that started on Thursday and continued through the weekend. Reports from Thursday indicate storm slabs were very reactive to snowmobile traffic, producing many size 1 to 1.5 storm slab avalanches that propagated widely. On Saturday, explosives control produced several size 2 to 3 wind slab avalanches in cross-loaded alpine start zones.

See more on the potential of triggering deeper weak layers in our latest Forecasters' Blog.

Snowpack Summary

Stormy weather over the past week has brought 40 to 80 cm of new snow to the region. Warm windy weather is causing storm snow to settle into reactive slabs. The storm snow sits on previously wind-affected snow. Below this, a melt-freeze crust is found on sun-exposed slopes and everywhere below 1600 m.

Several crust/facet/surface hoar layers exist in the upper and middle portions of the snowpack. Recent observations suggest these layers are gaining strength, but remain on our radar as active loading continues.

The most concerning persistent weak layer is at the base of the snowpack from large and weak facets formed in November. This layer is widespread and most likely problematic in steep, rocky alpine and upper treeline terrain.

Weather Summary

Sunday Night

Mainly cloudy with clear periods and isolated flurries, trace accumulation. Alpine temperatures reach a low of -6 C. Ridge wind westerly 30-50 km/h. Freezing levels fell from 1500 m to 500 m.

Monday

Mainly cloudy with scattered flurries becoming hevy in the afternoon. 2-8 cm accumulation. Alpine temperatures rise to -4 C. Ridge wind southwest 40-60 km/h. Freezing level rises to 1400 meters.

Overnight 5-10 cm accumulation, up to 20 cm in localized areas.

Tuesday

Clear with cloudy periods and isolated flurries, trace cm accumulation. Alpine temperatures drop to -6 C. Ridge wind west 10-30 km/h. Freezing level drops to 1000 meters.

Wednesday

Mix of sun and cloud with the possibility of light flurries, 2-5 cm accumulation. Alpine temperatures rise to -7 C. Ridge wind southwest 40-60 km/h. Freezing level rises to 800 meters.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Expect slab conditions to change drastically as you move into wind exposed terrain.
  • Watch for rapidly changing conditions during periods of heavy loading from new snow, wind, or rain.
  • Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.

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.

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.

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.