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Avalanche Forecast

Archived

Feb 3rd, 2023–Feb 4th, 2023

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

Regions

Kakwa, Pine Pass, Tumbler.

New snow and wind are creating very dangerous conditions. Travel in avalanche terrain at alpine and treeline elevations is not recommended.

Confidence

High

Avalanche Summary

Heavy snow is causing an ongoing natural avalanche cycle that started on Thursday and will likely continue into Saturday morning. Reports from Thursday indicate storm slabs were very reactive to snowmobile traffic around Pine Pass, producing many size 1 to 1.5 storm slab avalanches that propagated widely. With additional snow, we expect storm slab avalanches to be much larger on Saturday. Human-triggered avalanches will be very 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. See more on the potential of triggering deeper weak layers Forecasters' Blog.

Snowpack Summary

Stormy weather over the past few days has brought 50 to 80 cm of new snow around Pine Pass and 30 to 50 cm around Tumbler Ridge and Kakwa. Warm windy weather has caused this storm 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 not as concerning as in neighbouring regions.

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 terrain.

Weather Summary

Friday night

Storm eases off with another 10 to 15 cm around Pine Pass and 5 cm around Tumbler Ridge and Kakwa, 40 to 60 km/h southwest wind, treeline temperatures drop to -6 °C.

Saturday

Mostly cloudy with isolated flurries brining trace amounts of snow, sunny breaks possible in the afternoon, 30 to 50 km/h southwest wind, treeline temperatures warm to -3 °C.

Sunday

Cloudy with snowfall, 5 to 15 cm, 40 to 60 km/h southwest wind, treeline temperatures around -5 °C

Monday

Cloudy with snowfall, 5 to 15 cm, 50 to 70 km/h southwest wind, treeline temperatures around -3 °C

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
  • Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.
  • Stick to non-avalanche terrain or small features with limited consequence.
  • Be aware of the potential for large, destructive avalanches due to the presence of deeply buried weak layers.

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.