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Avalanche Forecast

Archived

Dec 8th, 2021–Dec 9th, 2021

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

Regions

South Columbia.

Triggering avalanches is possible at upper elevations, especially on wind-loaded slopes near ridges. 

Confidence

Moderate - A small change in the upper snowpack could dramatically change avalanche conditions.

Weather Forecast

Unsettled weather until the next storm arrives on Saturday.

WEDNESDAY NIGHT: Cloudy with scattered flurries brining 5-10 cm of snow, moderate wind from the west with gusts to 50 km/h, treeline temperatures drop to -10 C.

THURSDAY: Mostly cloudy with scattered flurries bringing up to 5 cm of low density snow, light wind from the west with some moderate gusts, treeline temperatures around -10 C.

FRIDAY: Mix of sun and cloud with some scattered flurries bringing trace amounts of snow, moderate wind from the southwest, treeline temperatures reach -8 C.

SATURDAY: Periods of snow with 10-20 cm by the afternoon, strong wind from the south, treeline temperatures reach -5 C.

Avalanche Summary

Avalanche activity since the last atmospheric river has mostly been limited to small (size 1) avalanches in the top layers of snow. Windy conditions on Wednesday may have caused some avalanche activity in the alpine, but there are no reports at time of publishing. 

Pay close attention to changes in the surface snow. Slabs could begin forming as loose snow settles and gets blown around by wind.

Snowpack Summary

10-20 cm of fresh snow sits above a thin breakable crust. A widespread crust formed during last week's atmospheric river and is now 20-40 cm deep. This crust extends into the alpine (as high as 2400 m), and there is some concern about the bond of the snow to this crust. Recent wind has likely formed fresh wind slabs at upper elevations.

The snowpack structure is relatively simple beneath this crust. Treeline snow depths are roughly 100-200 cm with an early November crust layer in the lower snowpack. While some faceting has been reported around this crust, it does not appear to be problematic.

Terrain and Travel

  • Be carefull around freshly wind loaded features.
  • Closely monitor how the new snow is bonding to the crust.
  • Be alert to conditions that change with elevation and wind exposure.

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.