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Avalanche Forecast

Archived

Feb 1st, 2023–Feb 2nd, 2023

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

Regions

Pine Pass, Tumbler.

Updated on Thursday at 6:45 AM Pacific: New snow and wind is creating very dangerous conditions in the alpine. Fresh storm slabs are building at all elevations and will likely increase in reactivity as it continues to snow and blow through the day. A small avalanche could step down to deeper weak layers.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported on Tuesday.

Many wind slab avalanches were triggered by riders and naturally last Saturday. They occurred on all aspects.

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 20 cm of fresh low-density snow may form new storm slabs and wind slabs in leeward terrain features. The snow will rest 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

Wednesday Night

Cloudy new snow 5-10 cm. Ridgetop wind 20-40 km/h from the west. Treeline temperatures steady -12 °C.

Thursday

Cloudy with snowfall, accumulation 10-20 cm by late afternoon with local enhancements possible. Ridgetop wind 30-50 km/h from the west and treeline temperature -10 °C.

Friday

Cloudy with snowfall, accumulation 10-20 cm. Ridgetop wind 40-60 km/ h from the west. Treeline temperature -6 °C.

Saturday

Cloudy with snowfall, accumulation 5 to 10 cm. Ridgetop wind 30-40 km/h from the southwest and treeline temperatures warming to -5 °C. Freezing level 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid the alpine during periods of heavy loading from new snow wind and/or rain.
  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • Be aware of the potential for large, destructive avalanches due to the presence of deeply buried weak layers.
  • Uncertainty is best managed through conservative terrain choices at this time.

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.