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 11th, 2023–Feb 12th, 2023

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

Regions

North Rockies, Kakwa, McGregor, Pine Pass.

Warm temperatures on Sunday will make higher elevations a lot more enticing than lower down, potentially drawing you into more places where wind slab formation is ongoing. Keep seeking sheltered spots! Triggering a wind slab right now is probably the most effective way to cause a large and destructive step-down avalanche.

Confidence

Moderate

Avalanche Summary

Recent observations have shown a trend away from very large persistent slab and deep persistent slab avalanches and toward surface instabilities such as wind slabs. We expect this trend to continue, however the basal snowpack remains questionable and should still figure into terrain selection around steep features with shallow or variable snowpack areas where these layers may be more easily triggered by a person or machine as well as large wind slab or cornice releases.

As recently as last week, very large natural avalanches were observed failing on deep snowpack layers. Two were size 3 persistent slab avalanches on steep north-facing aspects with 750 m wide crowns. A size 3.5-4 deep persistent slab avalanche was also observed. It is suspected this avalanche failed in depth hoar at the base of the snowpack.

Snowpack Summary

15-20 cm of new snow should accumulate in the region by end of day Sunday, adding to roughly 80 to 130 cm of recent storm snow from steady stormy weather over the past week. This storm snow is reportedly forming a good bond with previously wind-affected surfaces as well as the late January melt-freeze crust found on sun-exposed slopes and on all aspects below about 1600 m.

Several strengthening crust/facet/surface hoar layers can still be found in the upper and middle portions of the snowpack. The most concerning persistent weak layer, however, is at the base of the snowpack and composed of large and weak facets formed in November. This layer is widespread and most likely to be triggered in steep, rocky alpine and upper treeline terrain.

Weather Summary

Saturday night

Cloudy with flurries bringing about 5 cm of new snow. Strong southwest winds.

Sunday

Cloudy with increasing snowfall bringing 10-15 cm of new snow to higher elevations, light rain below 1500 metres. Continuing overnight with snow at most elevations. Strong to extreme southwest winds. Treeline high temperatures around 0 with freezing levels rising to 1700-1800 metres.

Monday

Cloudy with easing flurries bringing 15-25 cm of new snow, including overnight amounts. Light to moderate southwest winds shifting west. Treeline high temperatures around -7.

Tuesday

Mainly cloudy with isolated flurries. Light northwest winds shfting southwest. Treeline high temperatures around -8

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.

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.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.