Avalanche Forecast

Issued: Feb 3rd, 2023 4:00PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs and Deep Persistent Slabs.

Avalanche Canada shorton, Avalanche Canada

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

Summary

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

An icon showing Storm Slabs

30 to 80 cm of new snow has formed reactive storm slabs, especially on wind-loaded slopes. Storm and wind slab avalanches may step-down to deeper weak layers and initiate large and destructive avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

A layer of large and weak facets sits near the base of the snowpack. This layer is most prominent in upper treeline and lower alpine elevations. Storm slab avalanches could step down to this layer initiating very large avalanches. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3.5

Valid until: Feb 4th, 2023 4:00PM