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Avalanche Forecast

Archived

Feb 21st, 2023–Feb 22nd, 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 unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Lizard-Flathead, South Rockies, Flathead, Lizard, Elkford East, Elkford West.

25-35 cm of recent snow and northerly winds have formed fresh wind slabs that are sitting on hard surfaces. Reactive wind slabs may be found on aspects that are generally windward, so be on the lookout for wind slabs on most aspects in open terrain.

Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.

Confidence

Moderate

Avalanche Summary

Numerous naturally triggered storm slab avalanches up to size 2.5 were reported primarily in the alpine on Tuesday. Several skier triggered storm slab avalanches up to size 1.5 were also reported.

Recently formed storm slabs will likely remain reactive to human triggers; especially in open areas where the wind has stiffened the snow.

The deep persistent slab problem continues to be a concern for parts of the region. In the nearby Bull River area, this very large older avalanche was observed on Friday by the Avalanche Canada field team which is expected to have occurred on Wednesday.

Snowpack Summary

25-35 cm of recent snow and northerly winds have formed fresh wind slabs that are sitting on hard surfaces. Reactive wind slabs may be found on aspects that are generally windward, so be on the lookout for wind slabs on all aspects in open terrain.

The middle of the snowpack is well consolidated and sits on a thick crust. The bottom of the snowpack still consists of weak, sugary crystals that are slowly gaining strength in areas with a deeper snowpack.

Deep persistent slab avalanches should still be on your radar in thinner snowpack areas outside of the Lizard Range such as the Elkford area, and the Flathead range.

Weather Summary

Tuesday night

Cloudy with isolated flurries; 0-3 cm / Moderate, east ridgetop wind / Low temperature at treeline around -30 C.

Wednesday

Mostly cloudy / Moderate, east ridgetop wind / High temperature at treeline around -22 C.

Thursday

Mix of sun and cloud / Strong, southeast ridgetop wind / High temperature at treeline around -25 C.

Friday

Sunny / Strong, west ridgetop wind / High temperature at treeline around -17 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Avoid travelling on slopes below cornices.

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.