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Avalanche Forecast

Archived

Feb 3rd, 2022–Feb 4th, 2022

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

Northwest Coastal.

New snow and strong winds are building fresh and reactive storm slabs while rain soaks the snowpack at low elevations. Natural and rider triggered avalanches are likely on Friday.

Confidence

Moderate - Uncertainty is due to difficult to forecast freezing levels. Forecast precipitation (either snow or rain) amounts are uncertain.

Weather Forecast

Thursday night: 5-15 cm in most areas, heavier amounts in coastal areas, falling as rain at low elevations. Extreme SW wind. Freezing level 500 m.

Friday: 5-15 cm in most areas, falling as rain at low elevations. Strong SW wind. Freezing level 1000 m. Alpine temperature around -1 C.

Saturday: A mix of sun and cloud. Moderate to strong W wind. Freezing level 800 m. Alpine temperature around -4 C.

Sunday: Snowfall 10-20 cm. Strong SW wind. Freezing level 1000 m. Alpine temperature -2 C.

Avalanche Summary

On Wednesday, natural activity was limited to a few size 1 storm slabs. Storm slabs were reactive to ski cuts to size 1 and explosives averaging size 2.

Snowpack Summary

10-30 cm of new snow is forecast to accumulate by the end of Friday. This now brings 50-100 cm of recent snow above a variety of surfaces that formed during the end of January. This interface is made up of a crust, facets, and surface hoar. The crust can be found at or below treeline as well as on south-facing terrain in the alpine. In isolated sheltered terrain at treeline surface hoar has formed along with facets above this crust. Where a crust did not form facets will likely be found.

The January 19th surface hoar layer can still be found down 40 to 60 at treeline and above in sheltered terrain. Recent reports indicate that it is becoming less of a concern.

Terrain and Travel

  • As the storm slab problem gets trickier, the easy solution is to choose more conservative terrain.
  • Minimize exposure during periods of heavy loading from new snow, wind or rain.
  • Travel in alpine terrain is not recommended.
  • Keep in mind that wet avalanches can be destructive due to their high density.

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.

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.