Avalanche Forecast

Archived

Feb 1st, 2022–Feb 2nd, 2022

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.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Kootenay Boundary.

Expect fresh wind slabs to form as westerly winds strengthen, navigate carefully around wind loaded terrain features and ridgelines.

Approach sheltered slopes at treeline and below carefully, buried surface hoar may produce larger avalanches than you expect.

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

Arctic air brings cold temperatures, wind and little chance of snow until Friday.

TUESDAY NIGHT: Clearing skies with scattered cloud. Moderate norwest winds. A chance of flurries. Freezing levels at valley bottom.

WEDNESDAY: Cloudy with sunny breaks. Moderate to strong westerly winds. Flurries bring up to 5cm to the west boundary of the region late in the day. Freezing levels at valley bottom. Alpine high of -12.

THURSDAY: Cloudy with sunny breaks. Moderate to strong westerly winds. Chance of flurries. Alpine high of -7. Freezing level valley bottom.

FRIDAY: 10cm of snow with strong southwest winds. Alpine high of -5.

Avalanche Summary

On Monday, a natural avalanche cycle was observed mid storm producing storm slabs to size 1.5. Storm slabs were also triggered from ski cutting and explosive control work size 2.

All avalanches reportedly failed within the storm snow, or on the buried surface hoar layer immediately below. Avalanche activity occurred at treeline and above, mainly on North through East aspects (lee to the southwest winds).

Snowpack Summary

At lower elevations up to 30cm of storm snow sits over a melt freeze crust. In sheltered terrain a widespread layer of surface hoar sits immediately above the crust, typically 5-15 mm but as big as 30 mm in some areas.

At higher elevations the storm snow is being redistributed by moderate to strong westerly winds, over a previously wind affected snow surface. A thin melt freeze crust extends into the alpine on solar aspects. This crust may sit on the surface in exposed terrain, or below wind deposited snow in sheltered features.

The upper snowpack then consists of several crusts and surface hoar layers, 30-60 cm deep. Recent reactivity has appeared limited to the storm snow and most recent surface hoar.

The early December crust/facet persistent weak layer is buried down 100-200 cm and has been responsible for sporadic avalanche activity throughout the first half of January. The layer has been mainly dormant in the region for the past couple weeks but still remains a concern. See the most recent forecaster blog for more details on this layer.

Terrain and Travel

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Wind slabs may be poorly bonded to the underlying crust.
Continue to make conservative terrain choices while the storm snow settles and stabilizes.
Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.

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.