Avalanche Forecast

Archived

Dec 4th, 2019–Dec 5th, 2019

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Lizard-Flathead.

Caution as you transition into wind-exposed terrain. Avalanches are possible near and above tree line where wind slabs have formed.

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

Wednesday night: Cloudy, scattered snow with 1-4 cm possible, moderate southwest winds, alpine high temperature -4 C, freezing level around 1100 m.

Thursday: Cloudy with periods of sun, isolated flurries with a trace of accumulation possible, light southwest winds, alpine high temperature -3 C, freezing level around 1400 m.

Friday: Cloudy with periods of sun, isolated flurries with a trace of accumulation, moderate southwest winds, alpine high temperature -2 C, freezing level around 1500 m.

Saturday: Mainly cloudy, 7-12 cm of snow, light southwest wind, alpine high temperature of -2 C, freezing level dropping from around 1400 m.

Avalanche Summary

There have been few recent avalanches reported in the region. A couple of small wind slabs triggered by explosives have been observed. If you are getting out into the mountains, let us know what you see by posting to the Mountain Information Network!

Snowpack Summary

Strong westerly winds have redistributed the 10-15 cm of recent snow into wind slabs on lee features at upper elevations. These lingering slabs sit on a mix of sugary faceted snow and hard wind affected snow.

The total snowpack depth is between 50-100 cm in the alpine, and tapers rapidly at lower elevations. Two crusts have been reported in the middle of the snowpack. There is uncertainty as to how well the snow is bonding to these crusts.

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.