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Archived

Avalanche Forecast

Mar 23rd, 2021–Mar 24th, 2021
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: South Coast.

Additional new snow and wind Tuesday night through Wednesday morning will promote storm and wind slab formation at upper elevations.

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

TUESDAY Night: Flurries, accumulation 5-10 cm, moderate west wind, treeline temperatures around -2 C.

WEDNESDAY: Cloudy with flurries bringing 5-15 cm of snow throughout the morning, 30-50 km/h southwest wind, freezing level 1200 m with treeline temperatures around -1 C.

THURSDAY: Cloudy with sunny periods, light northeast wind, freezing level climbing to 1500 m with treeline temperatures near 1 C.

FRIDAY: Cloudy with sunny periods, light northwest wind, freezing level around 1000 m with treeline temperatures -1 C. 

Avalanche Summary

On Monday there were some reports of size 1.5-2 human triggered avalanches in the Seymour backcountry (30-60 cm thick). See the photos here and here. Additionally there were reports of several size 1.5 explosives triggered storm slab avalanches.

Widespread storm slab avalanche activity was reported on Sunday, and preliminary reports from Monday suggest they were still reactive to human triggering. On Sunday numerous size 1-2 natural slab avalanches were observed in the North Shore mountains. These avalanches were mostly 20-30 cm thick and ran on a crust layer.

Snowpack Summary

By mid morning Wednesday there could be 10-25 cm of new snow to add to the 35-45 cm of snow from Sunday which has likely settled and bonded to the old snow surface below. Along ridgelines, cornices are large and always have the potential of failing or being triggered from the weight of a human.

Terrain and Travel

  • Watch for avalanche hazard to increase throughout the day.
  • Exercise caution on steep, unsupported slopes.
  • Be careful as you transition into wind affected terrain.
  • Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Avalanche Problems

Storm Slabs

Recent snow and wind will renew storm and wind slabs at upper elevations. The reactivity of storm slabs should assessed before approaching steep open terrain especially where exposed to the wind. 

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Cornices

Cornices are large and looming along many ridgelines, and have likely grown with the recent snow and wind.

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

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3