Avalanche Forecast

Archived

Nov 22nd, 2019–Nov 23rd, 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.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Lizard-Flathead.

The snowpack has shown recent instability in the alpine. Conservative travel and being on high-alert is important to manage early-season uncertainties.

Confidence

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

Weather Forecast

FRIDAY NIGHT: Partly cloudy skies, light to moderate west wind, alpine temperature -4 C, freezing level below valley bottom.

SATURDAY: Cloudy with afternoon snowfall, accumulation 2 to 5 cm, moderate to strong west wind, alpine temperature -5 C, freezing level 1200 m.

SUNDAY: Morning snowfall and afternoon clearing, accumulation 2 to 5 cm, moderate to strong west wind, alpine temperature -5 C, freezing level 1300 m.

MONDAY: Partly cloudy skies, light west wind, alpine temperature -8 C, freezing level below valley bottom.

Avalanche Summary

Numerous storm slab avalanches were observed across the region on Tuesday and Wednesday. It is likely that they were sliding on the melt-freeze crust described in the snowpack summary.

Observations are limited right now, with recreationists starting to get into the mountains and operations soon to open. If you see anything while out in the field, please consider sharing that information with us and fellow recreationists via the Mountain Information Network (MIN).

Snowpack Summary

The snowpack is highly variable in the mountains this early in the season. The snowline starts at about 1500 m. At around 1650 m, you may find about 40 cm of snow. As you move higher into the alpine, you could find between 50 and 100 cm of snow.

Two melt-freeze crusts exist in the middle and near the bottom of the snowpack. There is uncertainty with how the snow is bonding to these crusts, and they may act as a sliding layer for snow above them. This requires conservative travel and being on high-alert to manage the uncertainty.

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.