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Avalanche Forecast

Archived

Feb 2nd, 2023–Feb 3rd, 2023

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

Regions

Kakwa, Pine Pass, Tumbler.

New snow and wind are creating very dangerous conditions. It's a good time to avoid avalanche terrain. Touchy storm slabs exist at all elevations. A small avalanche could step down to deeper weak layers.

Confidence

High

Avalanche Summary

On Thursday a widespread natural avalanche cycle was reported in Pine Pass and we suspect across the region.

Looking forward, natural and rider-triggered storm and wind slab avalanches are likely as we receive new snow and strong wind through the forecast period. Smaller 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.

The AvCan APP is LIVE! Please continue to send in your observations through the MIN.

Snowpack Summary

Up to 30 cm of new snow (with a bunch more expected overnight Thursday and into Friday) accompanied by strong to extreme westerly winds has formed widespread reactive storm slabs. The 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 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

Thursday Night

Cloudy new snow 10-20+ cm. Ridgetop wind 70-100 km/h from the southwest. Treeline temperatures steady -8°C.

Friday

Cloudy with snowfall, accumulation of 10-20 cm by late afternoon with higher amounts on the western slopes of the region. Ridgetop wind 50-80 km/h from the west and treeline temperature -8°C. Freezing levels 1300 m.

Saturday

Cloudy with snowfall, accumulation 5-10 cm. Ridgetop wind 40-60 km/ h from the southwest. Treeline temperature -6 °C. Freezing level 1500 m.

Sunday

Cloudy with snowfall, accumulation 5 to 10 cm. Ridgetop wind 30-50 km/h from the southwest and treeline temperature -5 °C. Freezing level 1500 m.

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.
  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • 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.