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Avalanche Forecast

Archived

Jan 13th, 2023–Jan 14th, 2023

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

Regions

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

Hazard will improve as precipitation stops and freezing levels lower throughout the day.

The storm brought a mix of rain and snow to higher elevations. As you transition into dry snow and wind-blown areas watch for cohesive storm slabs that are reactive to human triggering.

Confidence

Moderate

Avalanche Summary

On Thursday, several natural loose wet avalanches, up to size 1, were observed below treeline. Several explosive-triggered, size 1.5 storm slab avalanches were reported.

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

Snowpack Summary

15-30 cm of new snow and strong southerly winds have built 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

Friday Night

Periods of snow continue, 5-10 mm. Winds will ease to southerly 40 km/h. Ridgetop low-temperature -1 C. Freezing levels will slowly fall to near 1500 m by Saturday morning.

Saturday

Cloudy with sunny periods and isolated flurries, trace accumulation. Southeast winds of 40 to 60 km/h. Ridgetop high-temperature -1 C. Freezing levels will be near 1500 m.

Sunday

Cloudy with sunny periods and isolated flurries, trace accumulation. Light variable winds gusting 20 km/h. Ridgetop high-temperature -1 C. Freezing levels 1200 m.

Monday

Cloudy with sunny periods and isolated flurries, 5 mm. Light variable winds gusting 20 km/h. Ridgetop high-temperature -3 C. Freezing levels 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Keep in mind that human triggering potential persists as natural avalanching tapers off.
  • Dial back your terrain choices if you are seeing more than 30 cm of new snow.
  • In times of uncertainty conservative terrain choices are our best defense.

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.