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Avalanche Forecast

Archived

Jan 17th, 2023–Jan 18th, 2023

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

Regions

Lizard-Flathead, Flathead, Lizard, Moyie.

Keep an eye on recent wind loading patterns to avoid new slabs, but save some of your mental bandwidth for the deeper issue - a weak basal snowpack structure that continues to demand diligent group management. Regroup in safe locations, space out, and avoid shallow rocky start zones.

Confidence

Moderate

Avalanche Summary

Ski cutting in the Fernie area on Monday yielded small (size 1) wind slab releases after the area received 15 cm of new snow. Natural dry loose releases from steep alpine terrain reached size 1.5.

Please continue to share any observations or photos on the Mountain Information Network.

Snowpack Summary

Forecast light flurries will add to 10-15 cm of recent snow now settling on a crust below 2000 metres and to wind-affected surfaces above this elevation.

A crust/facet layer is down 50-90 cm (and 2-15 cm thick at TL elevation). Where it's thickest, it caps a well settled and consolidated mid-snowpack.

Another crust/facet layer is down 70-150 cm. Below this crust, the basal snowpack is weak and faceted. Treeline snow depths average 120-250 cm.

Weather Summary

Tuesday night

Mainly cloudy with isolated flurries. Light to moderate southwest winds, increasing into the morning.

Wednesday

Cloudy with isolated flurries. Moderate southwest winds, potentially strong in the alpine, increasing over the day. Treeline high temperatures around -5.

Thursday

Cloudy with scattered flurries bringing less than 5 cm of new snow. Light to moderate southwest winds, easing over the day. Treeline high temperatures around -3.

Friday

Diminishing cloud and flurries with a further trace of new snow. Light southwest or northwest winds, potentially strong in the alpine, easing over the day. Treeline high temperatures around -6.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • Wind slabs are most reactive during their formation.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.