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Avalanche Forecast

Archived

Jan 10th, 2023–Jan 11th, 2023

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

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

Multiple snowpack weaknesses are in play and Wednesday's wind forecast would like to offer one more - new wind slab formation in places our new snow hasn't been sealed off by a surface crust.

Confidence

Moderate

Avalanche Summary

No recent avalanches have been reported, but there have likely been natural avalanche cycles during the recent storms. Large human-triggered avalanches will continue to be a concern on Wednesday due to a combination of recent snow, increasing winds, and a potential weak layer and crust buried 60 to 100 cm deep.

Snowpack Summary

Warm temperatures on Tuesday likely allowed for a melt-freeze crust to form on the surface at all but high alpine elevations. This crust will top wide-ranging and rapidly settling new snow amounts of 10-40 cm from Monday night. Everywhere a crust has formed, it should prevent Wednesday's forecast strong winds from forming new wind slabs.

Storms over the past week deposited 70 to 110 cm over a thin crust layer above 1000 m. This crust has been highlighted as a critical avalanche layer in recent snowpack tests. Frequent rain has been eroding the already thin snowpack below this elevation.

Snowpack depths at treeline are around 120 cm, tapering quickly with elevation. Although the snowpack in most forested areas below treeline remains below threshold depths for avalanches, many steep bluffs, cutbanks, and alpine features in the upper below treeline band are capable of producing avalanches.

Weather Summary

Tuesday night

Mainly clear. Light southeast winds.

Wednesday

Becoming cloudy with flurries bringing up to 5 cm of new snow by end of day and increasing overnight. Strong southeast winds. Treeline high temperatures around 0°C with freezing levels around 1300m.

Thursday

Stormy weather with 15-20 cm of new snow from the overnight period and another 15-30 mm over the day as snowfall shifts to rain at all but high alpine elevations, continuing overnight. Extreme south winds. Treeline high temperatures reaching +3 as freezing levels climbs from 1000 to 1800 m throughout the day.

Friday

Cloudy with continuing heavy rain at all but highest alpine elevations. Extreme south winds. Treeline high temperatures around +4 with freezing levels between 1800 to 2100m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Avoid lee and cross loaded slopes in the alpine.

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.

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.

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.