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Avalanche Forecast

Archived

Jan 12th, 2023–Jan 13th, 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 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.

Regions

South Coast Inland, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

Forecasters are uncertain about how deep persistent weak layers will react to the storm's heavy wind, rain, and snow inputs.

Uncertainty is best managed through conservative terrain choices at this time.

Confidence

Low

Avalanche Summary

No new avalanches were reported in the region since Wednesday. Backcountry users should expect to see evidence of a natural avalanche cycle from within the storm at all elevations.

Please continue to post your observations and photos to the Mountain Information Network. It helps strengthen our data gathering.

Snowpack Summary

10-20 cm of new snow and strong southerly winds are building reactive storm slabs in lees. New snow overlies previous wind-affected surfaces and possibly a sun melt-freeze crust on steep solar slopes.

In sheltered terrain, 40 to 70 cm of low-density snow sits over a crust formed in late December. This crust varies in thickness throughout the terrain and elevation. Uncertainty remains about the robustness of this crust above 2100 m. Storm slab avalanches could potentially step down to this layer, creating larger-than-expected avalanches.

There is a widespread layer of facets and depth hoar at the bottom of the snowpack. Uncertainty remains around the likelihood of triggering this layer. Snowpack depths around treeline are about 150 cm deep. The snowpack below treeline is very shallow and faceted.

Weather Summary

Thursday Night

Stormy, 15-20 mm of precipitation expected. Extreme southerly ridge winds gusting 80-100 km/h. A high of +1C at treeline. Freezing rain is possible on the Duffey Lake Road as freezing levels rise to 1800 m.

Friday

Stormy, 10-15 mm of precipitation. Extreme southerly ridge winds gusting 80-100 km/h. A high of +2C at treeline. Freezing levels hover around 1800-2000 m.

By evening the storm subsides easing winds and precip.

Saturday

Mostly cloudy with isolated flurries, 5 mm. Moderate southwesterly winds gusting 30-50 km/h. A high of -1C at treeline. freezing levels drop to 1500 m.

Sunday

A mix of sun and cloud. Light variable winds gusting 20 km/h. A high of -2C at treeline. Freezing levels continue dropping to 1200 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Minimize exposure during periods of heavy loading from new snow, wind or rain.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Closely monitor how the new snow is bonding to the crust.

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.