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Avalanche Forecast

Archived

Mar 8th, 2022–Mar 9th, 2022

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

Regions

Sea To Sky.

A persistent slab problem requires diligence and a conservative mindset. Be confident the problem doesn't exist before committing to consequential terrain.

Confidence

High - Confidence is due to a stable weather pattern; little change is expected for several days.

Weather Forecast

TUESDAY NIGHT: Clear skies with no precipitation, 30 to 40 km/h north wind, alpine temperature -13 C.

WEDNESDAY: Clear skies with no precipitation, 20 to 30 km/h north wind, alpine temperature -12 C.

THURSDAY: Mix of sun and cloud with late afternoon snowfall, trace accumulation, 30 km/h southwest wind, alpine temperature -7 C.

FRIDAY: Cloudy with snowfall, accumulation 5 cm, 40 to 60 km/h southwest wind, alpine temperature -5 C.

Avalanche Summary

We continue to receive reports of persistent slab avalanches, which are releasing on the weak layer described in the Snowpack Summary. The avalanches have typically occurred on northwest to northeast aspects at treeline and alpine terrain. The avalanches have been triggered by riders, naturally, and remotely. Some of the avalanches propagated far, around 200 to 300 m.

Looking forward, it remains possible that persistent slab avalanches could be triggered. Naturally-triggered avalanches may be on the decrease during this cool weather period, but human triggering is possible.

Snowpack Summary

A dusting of snow sits on a surface melt-freeze crust on all aspects below around 1500 m and on sun-exposed slopes into the alpine. Settled dry snow remains on shaded slopes above around 1500 m. Reports suggest that recent strong northerly wind did not form new wind slabs, though extra caution is advised in steep terrain where isolated pockets may have formed.

Around 40 to 80 cm deep, a weak layer of sugary faceted grains may be found above a melt-freeze crust that formed in February. This layer has produced numerous human-triggered and natural avalanches over the past week. Activity has been most prevalent on northeast to northwest aspects at treeline and alpine elevations. Check out this forecaster blog for more info.

There are no deeper concerns at this time.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Be aware of the potential for wide propagation.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.