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Avalanche Forecast

Apr 23rd, 2021–Apr 26th, 2021
Alpine
2: Moderate
Treeline
2: Moderate
Below Treeline
1: Low
Alpine
3: Considerable
Treeline
3: Considerable
Below Treeline
2: Moderate
Alpine
3: Considerable
Treeline
3: Considerable
Below Treeline
2: Moderate

Regions: South Coast Inland.

Up to 30 cm of new snow is forecast for upper elevations by Sunday. New and reactive storm slabs may build at treeline and in the alpine. 

This is the last forecast of the season.

Thanks for the great winter and play safe!

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

A weather system will approach the BC coast today. Tonight, the system will pivot towards the southern half of BC. The system will stall over southern BC tonight through the weekend resulting in persistent rain showers and alpine snow. The convective nature associated with this system could bring higher localized precipitation amounts.

Friday Night: Mostly cloudy with some isolated flurries. Winds light from the southeast. Alpine temperatures near -1 C and freezing levels 1500 m.

Saturday: Snow 5-10 cm at upper elevations. Wind light from the South. Alpine temperatures near -1 and freezing levels 1600 m. 

Sunday: Snow 5-10 cm at upper elevations. Light wind from the South. Alpine temperatures -2 and freezing levels 1600 m. 

Monday: Cloudy with some sunny periods and snow 5 cm. Light-moderate wind from the southwest. Alpine temperatures near -1 and freezing levels 1800 m.

Avalanche Summary

At treeline and in the alpine, the new snow combined with light to moderate wind may build fresh and reactive storm slabs. The new snow may have a poor bond to the old snow surfaces which are mostly crusts. Below treeline will see rain and will likely keep snow surfaces wet and weak below the treeline elevations. Loose wet avalanches are possible. 

Cornices remain weak and fragile. They require a large berth from above and below as they are very unpredictable.

Over the past week natural and explosive triggered wet slab avalanches were reported mostly from large solar slopes and running to valley bottom up to size 3.5. An ongoing natural cycle of wet loose avalanches up to size 2 has been the theme with the warming.

Snowpack Summary

New snow will accumulate at treeline and in the alpine through the weekend building fresh and reactive storm slabs. Below treeline elevations will likely see rain. The new snow will be landing on a melt-freeze crust that extends to the alpine on solar slopes and 2100 m on polar slopes. It may bond poorly. Rain below treeline will likely keep the snow surfaces wet and weak.

Cornices are large and looming along ridgelines. They are weak and very unpredictable. 

Terrain and Travel

  • Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
  • Keep in mind that wet avalanches can be destructive due to their high density.

Avalanche Problems

Storm Slabs

New snow is forecast for upper elevations and the region may receive up to 30 cm by Sunday. Reactive storm slabs may exist if there is a poor bond to the old snow surfaces comprising of mostly crusts and firm snow on North facing alpine slopes.

Dry loose sluffing may be seen from steep terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Loose Wet

Wet loose avalanches are possible below treeline with forecast rain. If a firm crust exists this problem is unlikely.  

Aspects: All aspects.

Elevations: Below Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Cornices

Cornices are at their largest at this time of year. They are weak and unpredictable. 

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 2 - 3