Avalanche Forecast

Issued: Apr 7th, 2022 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Storm Slabs and Cornices.

Avalanche Canada wlewis, Avalanche Canada

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Overnight freezing level change, rain and snow leaves uncertainty over how the snowpack will react.

During times of uncertainty lean on a conservative approach to terrain, cautious mindset and constantly make observations while you travel.

Summary

Confidence

Low - Uncertainty is due to rapidly fluctuating freezing levels. Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

THURSDAY NIGHT: Freezing levels fall from 3000 m to around 1500 m by morning. Precipitation begins as rain and transitions to snow, with 10-20 mm forecast for the Duffy and Coqhuihalla. Allison Pass is likely to receive around 5 mm. Strong to extreme southwest winds. 

FRIDAY: Mostly cloudy with continued snowfall of up to 10 cm. Freezing levels remain around 1500 m. Moderate to strong westerly winds. 

SATURDAY: Mostly cloudy with flurries of up to 5 cm. Freezing levels around 800 m. Moderate westerly winds.

SUNDAY: Clearing skies with scattered flurries possible. Freezing levels remain below 1000 m. Moderate westerly winds. 

Avalanche Summary

High freezing levels and a mix of rain and snow overnight may produce a natural avalanche cycle.

On Wednesday, natural wet avalanches were observed up to size 2.5 in steep terrain features. Natural cornices falls have also been observed within the last 3 days. 

Explosive control produced wind slabs up to size 2 in north and west facing terrain features, failing on the late March crust. 

On Tuesday, a skier remotely triggered two size 1 storm slabs from 2 m away on a northeast aspect at 2000 m in the north of the region. These were 30 cm thick and failed on the underlying melt-freeze crust. 

Snowpack Summary

Up to 30 mm of precipitation overnight with falling freezing levels will create a mixed bag of conditions on Friday, as snow continues to accumulate.

High elevations can expect up to 30 cm of fresh wind affected storm snow, that will likely be redistributed into deeper deposits on north and east facing slopes over a crust or moist snow. Another widespread and supportive crust is buried 30-50 cm deep, below recent settling storm snow. This crust has recently been reactive to human and natural triggers. 

Snow will transition to mixed precipitation and rain as elevation decreases. The lowest elevations will likely hold wet surface snow or a crust from heavy overnight rainfall. The middle and lower snowpack are generally strong and well bonded.

Southern terrain will see minimal new precipitation. Recent storm snow of around 50 cm will likely have a widespread crust or moist snow on the surface from Thursdays warming event. 

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

Problems

Storm Slabs

An icon showing Storm Slabs

Up to 30 mm of wet snow or rain will add to previous storm totals of 30-50 cm sitting on a reactive crust that has produced large avalanches in the last 3 days. A natural cycle may occur overnight during peak precipitation. 

Storm snow is expected to be sensitive to human triggers and avalanches may involve the most recent snowfall, or the settling storm snow from the past week.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1.5 - 2.5

Cornices

An icon showing Cornices

Cornices have grown large during the recent storms and may remain weak from warm temperatures. Falling cornices are hazardous and may trigger slabs avalanches on the slopes below. 

Aspects: North, North East, East, South East, North West.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Apr 8th, 2022 4:00PM