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Avalanche Forecast

Archived

Mar 4th, 2022–Mar 5th, 2022

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

South Coast.

Lingering storm slabs may still be reactive on steep, unsupported slopes or where the storm snow overlies a weak crust/facet layer. Watch for new wind slab formation with the potential for periods of moderate northerly wind on Saturday. 

Confidence

Low - Uncertainty is due to the limited number of field observations. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack. Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

A ridge of high pressure brings dry and sunny conditions for the weekend. 

Friday Night: Clear, light N wind, freezing levels 800-1200 m.

Saturday: Sunny, light to moderate N wind, freezing levels reaching around 1500 m.

Sunday: Mainly sunny, moderate N wind, freezing levels potentially reaching around 2000 m in the late afternoon.

Monday: Mainly cloudy with a chance of flurries, strong NW wind, freezing levels around 1000 m.

Avalanche Summary

No new avalanches were reported on Thursday. However, widespread pinwheeling was observed on steep slopes on all aspects and elevations. Just north of the region in the Tantalus, widespread avalanche activity was observed between Wednesday afternoon and Thursday morning. 

On Wednesday, wet loose avalanches up to size 1 were easily triggered by skiers. No new natural avalanche activity was reported.

On Tuesday, a skier triggered storm slab size 1 was reported from a northeast aspect at treeline. Wet loose avalanches were easily triggered below treeline up to size 1. 

On Monday, several storm slabs were reported up to size 2. This followed a widespread natural storm slab avalanche cycle on Sunday. Skier-controlled storm slabs were triggering remotely and propagating widely at treeline and below as shown in this MIN report. Natural avalanche activity will likely continue through Wednesday with reactive storm slabs in the alpine and upper treeline and loose wet avalanches below treeline.

Snowpack Summary

A melt-freeze crust is now expected to be capping the snowpack on all aspects at lower elevations and on sun-exposed slopes at higher elevations. Dry surface snow may still exist on high elevation northerly aspects. 

A weak interface from mid-February can be found 30-60 cm deep. This interface includes a sun crust, facets, and surface hoar. This interface was bonding poorly at the beginning of the storm but has become less of a problem now where the snowpack is capped by a robust crust. At higher elevations where the snowpack is not capped by a crust, the interface may still be reactive. Check out the Sea to Sky Forecast and this forecaster blog to learn more about the recent reactivity on this layer which is still reactive just north of the region.

50-80 cm below the surface, a 30 cm thick crust caps the underlying snowpack which is well settled and strong.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Cornices become weak with daytime heating or solar exposure.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.

Problems

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.