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Avalanche Forecast

Archived

Feb 17th, 2023–Feb 18th, 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 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, human triggered possible.

Regions

Cariboos, Blue River, Clearwater, McBride, Premier, Quesnel, Sugarbowl, Clemina, North Monashee, Renshaw, Robson.

Monitor the amounts of new snow that have fallen and note whether it is consolidating into a slab. Back off into more simple terrain as the snow starts to consolidate.

Confidence

Moderate

Avalanche Summary

Numerous loose dry avalanches were reported on Thursday as the storm snow started to increase in depth with little slab property.

Going forward storm slabs may become touchy, especially where the new snow overlies a recently buried surface hoar layer. Variable winds will be developing wind slabs at upper elevations directly lee of ridges and high points.

Cornices are also growing in this area and will become weak and overhanging. Small avalanches may gain enough mass to trigger deeper weak layers.

Snowpack Summary

Another 10 to 15 cm of new snow overnight brings recent snowfall totals of 30 to 40 cm of low-density snow. Storm slabs may be more reactive where they have settled on a surface hoar layer that developed earlier this week.

Moderate variable winds throughout the day will be redistributing new snow into wind slabs at treeline and alpine elevations. A melt-freeze crust can be found below 1400 m and on steep solar aspects.

The mid-pack is showing signs of strengthening. A surface hoar layer down roughly 60 to 80 cm has not produced avalanches recently but can still be found in isolated terrain features specifically sheltered, treeline, and upper below treeline.

The lower snowpack is composed of large and weak facets from November located near the base of the snowpack. Additional load or step-down avalanches over the next few days may wake this layer up.

Weather Summary

Friday night

Cloudy with snowfall overnight into Saturday morning, 10 to 15 cm accumulation, 20 to 30 km/h west winds, treeline temperatures -10 °C.

Saturday

Cloudy with snowfall briefly easing in the afternoon, 2 to 4 cm accumulation, with snowfall starting again overnight. 10 to 20 km/h west winds, treeline temperatures -10 °C.

Sunday

Cloudy with snowfall, 8 to 12 cm accumulation, 20 to 30 km/h west winds, treeline temperatures -5 °C.

Monday

Cloudy with isolated flurries, 2 to 3 cm accumulation, 5 to 10 km/h northwest winds, treeline temperatures - 10 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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.