Avalanche Forecast

Issued: Mar 3rd, 2022 4:00PM

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

Avalanche Canada swerner, Avalanche Canada

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The March sun can really pack a punch and destabilize the upper snowpack. Natural and human triggered avalanches remain likely.

Conservative travel habits and patience is key, especially when dealing with a persistent weak layer deeper in the the snowpack.

Summary

Confidence

Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack. Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

Change is in the air with a strong ridge set up through the weekend. This will bring clear and sunny skies, light northerly wind, and rising freezing levels.

Thursday Night: Some cloud cover and light (convective) snowfall 10-15 cm. Ridgetop winds light to moderate from the northwest. Freezing levels dropping to 800 m.

Friday/ Saturday: Sunshine with some clouds. Ridgetop wind light to moderate from the northeast and alpine temperatures near -5. Freezing levels (diurnal) 1000 m or lower overnight and 1500 m during the day.

Sunday: Sunny skies with freezing levels rising to 2000 m during the day. Ridgetop wind moderate from the North and alpine temperatures possibly rising to -1 degrees. 

Avalanche Summary

No new avalanche observations were reported by Thursday afternoon. 

On Wednesday, numerous storm slab and loose wet avalanches up to size 2 were reported. Treeline and below treeline terrain saw wet loose avalanches up to size 2 as well. In the neighboring Sea to Sky region, a few skier controlled and remotely triggered (from as far away as 40 m) avalanches were also reported. These persistent slabs failed on the mid-February facet/ crust interface buried approximately 50 cm down. They caught people by surprise, but no involvements were associated.

On Tuesday afternoon, reports from the southern part of the region saw a widespread natural wet loose and wet slab cycle up to size 3. A few glide slab releases also occurred up to size 1.5. These avalanches may have actually occurred on Monday. In the northern part of the region, snowballing was seen from below treeline elevations. No new reports from the southern half of the region. 

Snowpack Summary

Anywhere from 40 cm to 60 cm of recent storm snow has accumulated in the North (Pemberton area) and up to 80 cm in the South (Coquihalla) over a variety of surfaces that were buried mid-February. These old interfaces include surface hoar and/or facets in shady, wind-sheltered areas, sun crust on solar aspects. Generally, the storm snow seems to be settling quickly. The snow is moist/wet and rain-soaked at lower elevations, especially in the southern half of the province.

In the neighboring Sea to Sky region on northerly slopes (NW, N, NE, E) at treeline/ low alpine elevations (1700-2000 m) the mid-February facet/ crust persistent weak layer has been touchy to skier triggers, showing signs of whumphing and remotely triggered avalanches. Reports indicate that areas that have 3-5 cm of facets sitting on a hard melt-freeze crust are most concerning. There is no direct evidence of this persistent slab problem in the South Coast Inland, however, it may be developing and should be on your radar because the snowpack structure is similar.

Another crust/facet layer from late-January is buried down 40-120 cm and has shown no results in recent snowpack tests and is dormant at this time.

Terrain and Travel

  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Watch for unstable snow on specific terrain features, especially when the snow is moist or wet.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Storm Slabs

An icon showing Storm Slabs

40 to 60 cm in the North and up to 80 cm in the South of recent storm snow has blanketed upper elevations. The likelihood of triggering a storm slab increases in steep or convex terrain and in wind loaded areas at upper elevations. 

Looming cornices have grown large during the recent storm. They could pose threat from above and below and weaken when the sun is out.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

In the adjacent Sea to Sky forecast region a persistent weak layer of facets on a crust exist 50 cm below the surface and has been touchy to human triggers, especially on northeast aspects at treeline (1700-1900 m). Remote triggering (from a distance away) is possible and a few size 2-2.5 avalanches failed easily on this layer Wednesday. 

There has been no direct reactivity reported in the South Coast Inland. However, the snowpack structure is similar in some locations and it should be on your radar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Loose Wet

An icon showing Loose Wet

The warm spring sun may easily trigger loose wet avalanches at all elevations, especially on south facing slopes. 

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 4th, 2022 4:00PM