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Avalanche Forecast

Archived

Jan 12th, 2022–Jan 13th, 2022

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

Regions

Northwest Inland.

Warming temperatures may increase the reactivity of recently formed wind slabs. Use extra caution around steep south facing slopes in the afternoon if the sun is shining brightly. 

Confidence

Moderate -

Weather Forecast

A ridge of high pressure brings dry and sunny conditions for Thursday before the next storm system reaches the coast Thursday night. 

Wednesday Overnight: Mainly cloudy, light variable wind, freezing level as high as 800 m. 

Thursday: A mix of sun and cloud, light variable wind, freezing level as high as 900 m. 

Friday: Snowfall 4-8 cm, strong SW wind, freezing level as high as 1400 m. 

Friday overnight and Saturday: Snowfall 5-10 cm, strong SW wind, freezing level climbing as high as 1200 m. 

Avalanche Summary

On Tuesday, a natural icefall triggered size 2.5 wind slab was reported on a NE aspect. At lower elevations closer to the coast where it was warmer, loose wet avalanches were observed. This MIN report and this one describe some recent wind slab activity. 

On Monday, loose dry avalanches up to size 2.5 were reported in the northwest of the region where upwards of 50 cm of recent storm snow had accumulated. No new avalanches were reported in the south of the region where substantially less storm snow had accumulated. On Sunday, a natural wind driven avalanche cycle was reported through many parts of the region. 

Snowpack Summary

15-30 cm of recent storm snow has been redistributed by periodic moderate to strong SW winds which has formed reactive wind slabs and created a heavily wind affected snow surface in the alpine. The recent storm snow overlies a previously wind-affected surface comprised of old hard wind slabs, sastrugi, and areas scoured to the ground or old crusts. Faceting above the old surface from the prolonged cold temperatures may increase the reactivity of the recently formed wind slabs which could end up persisting for longer than normal. With the mild temperatures and ongoing wind, cornices are reported to be growing larger. 

The base of the snowpack is composed of crusts and weak faceted grains, particularly in thin snowpack areas. While these layers have generally gone dormant in the region, they still have the possibility of waking up with new snow load or warming, and wind slab avalanches may still have the potential to step down to these deeper layers in isolated areas. 

Terrain and Travel

  • Stay off recently wind loaded slopes until they have had a chance to stabilize.
  • Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.

Problems

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.

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.