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Avalanche Forecast

Archived

Mar 22nd, 2022–Mar 23rd, 2022

Alpine
Natural avalanches possible, human triggered probable.
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 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

North Columbia.

Warm air is increasing avalanche danger. Conservative terrain travel is recommended given the weather and snowpack conditions.

Confidence

Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

TUESDAY NIGHT: Cloudy with isolated flurries, trace accumulation, 20 to 40 km/h southwest wind, alpine temperature 0 C, freezing level 2200 m.

WEDNESDAY: Cloudy with afternoon rain or snow, accumulation 2 to 5 cm above the rain-snow line and rain below, 20 to 40 km/h southwest wind, alpine temperature -1 C, freezing level 2100 m.

THURSDAY: Early-morning snowfall then clear skies, accumulation 10 to 20 cm, 10 km/h northwest wind, alpine temperature -7 C.

FRIDAY: Mostly cloudy with isolated flurries, accumulation 1 to 3 cm, 10 km/h southwest wind, alpine temperature -6 C.

Avalanche Summary

A few natural storm slab avalanches were observed out of steep terrain on Monday, generally within the top 30 cm of recent snow.

A few more persistent slab avalanches were triggered by riders, being 50 to 70 cm deep, on north to east aspects, and around treeline elevations. This adds to the many avalanches that have released on the weak layer described in the Snowpack Summary over the past couple weeks. This layer must be treated as suspect anywhere it exists.

Snowpack Summary

Freezing levels are forecast to remain around the lower alpine, warming up the snowpack. Small amounts of rain are forecast to fall below around 2000 m on Wednesday, with snow above. Rain will destabilize the snowpack, increasing the likelihood of wet loose avalanches. Up high, wind slabs may exist from recent snow and southwest wind.

A weak layer may be found around 50 to 100 cm deep. The layer consists of surface hoar crystals in treeline terrain in areas sheltered from the wind and otherwise a hard melt-freeze crust associated with weak faceted grains on sun-exposed slopes (i.e., east, south, west). Check out this blog for more information. This layer continues to form large avalanches in the region, although activity appears to be decreasing each day.

There are presently no deeper concerns.

Terrain and Travel

  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.