Avalanche Forecast

Archived

Mar 20th, 2023–Mar 21st, 2023

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, Akamina, Flathead, Lizard.

Lingering wind slabs and cornices remain the main concern. Use extra caution during the heat of the afternoon.

Confidence

Moderate

Avalanche Summary

On Sunday, several natural size 1 loose wet avalanches were observed from steep terrain on solar aspects. A solar-triggered size 1.5 slab avalanche was also reported from a steep treeline feature.

On Saturday, a few natural size 1 wet loose avalanches were observed on alpine features that received direct sun in the afternoon.

If you head out in the backcountry, let us know what you are seeing by submitting a report to the Mountain Information Network.

Snowpack Summary

The snow surface consists of a sun crust on solar aspects, small facets and surface hoar on shady and wind-sheltered slopes, and wind-affected surfaces in exposed terrain. The wind recently shifted from the southwest to the northeast so while wind slabs are generally becoming less likely, they should still be expected on all aspects in exposed terrain.

The top layer of the snowpack at higher elevations is made up of 20 to 40 cm of dense, wind-affected snow. It tapers to a rain crust below 1400 m. This Top layer of snow may sit on a sun crust on solar slopes and small surface hoar in sheltered, shaded areas.

The mid-snowpack is generally well-settled. The lower snowpack includes a layer of weak sugary crystals near the ground. This layer has not produced recent avalanche activity.

Weather Summary

Monday Night

Clear, winds northeast 20-40 km/h, treeline low around -10 °C.

Tuesday

Sunny, winds northeast 10-20 km/h, freezing level reaching around 1800 m.

Wednesday

Sunny, winds northeast 15-30 km/h, freezing level reaching around 2000 m.

Thursday

Mainly sunny, winds southwest 15-30 km/h, freezing level reaching around 1800 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
Recent wind has varied in direction so watch for wind slabs on all aspects.
Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.