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Avalanche Forecast

Archived

Feb 20th, 2023–Feb 21st, 2023

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

Regions

Vancouver Island, East Island, South Island, West Island.

Recently formed wind slabs may remain reactive to human triggering at upper elevations, particularly where they overlie a crust.

At lower elevations, a crust on or near the surface will make for challenging travel conditions, but generally safe avalanche conditions.

Confidence

Moderate

Avalanche Summary

Last Friday our field team observed evidence of a natural storm slab cycle to size 2. These avalanches were generally on northwest aspects at treeline. They ran on a crust that is now 20-70 cm deep.

Snowpack Summary

A crust near or on the surface may extend into the alpine from warm temperatures and rain on Monday. At higher elevations, 10-20 cm of recent snowfall has been redistributed by northwesterly winds, scouring windward slopes and depositing wind slabs in lee areas. A crust can be found down 20-70 cm that extends to mountain tops on all aspects. Recent reports suggest this crust is bonding poorly to the snow above.

The remainder of the snowpack is consolidated and strong.

Weather Summary

Monday night

Cloudy with flurries, trace to 10 cm of accumulation. Alpine temperatures drop to a low of -3 °C. Ridge wind northwest 30 km/h gusting to 60 km/h. Freezing level 900 metres.

Tuesday

Cloudy with flurries, up to 5 cm accumulation. Alpine temperatures reach a high of -1 °C. Ridge wind 25 gusting to 55 km/h. Freezing level 1100 metres.

Wednesday

Cloudy with sunny periods and isolated flurries. Alpine temperatures reach a high of -9 °C. Ridge wind northeast 10-20 km/h. Freezing level 300 metres.

Thursday

A mix of sun and cloud. Alpine temperatures reach a high of -10 °C. Ridge wind east 5-15 km/h. Freezing level at valley bottom.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • A crust on the surface will help bind the snow together, but may make for tough travel conditions.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Closely monitor how the new snow is bonding to the crust.

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.