Avalanche Forecast

Archived

Mar 7th, 2022–Mar 8th, 2022

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.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Northwest Inland.

It's going to be a sunny day! Wind slabs were formed by extreme west and northwest wind on Sunday and might still be reactive to human triggers.

Confidence

High -

Weather Forecast

Monday night: Clear with cloudy periods, light northeast wind, alpine low -10 °C, freezing level at valley bottom.

Tuesday: Mainly sunny, moderate northeast wind, alpine high -9 °C, freezing level at valley bottom.

Wednesday: Mix of sun and cloud, light variable wind, alpine high -8 °C, freezing level at valley bottom.

Thursday: Cloudy, up to 5 cm snow, strong west wind, alpine high -6 °C, freezing level at valley bottom.

Avalanche Summary

On Sunday, a large natural slab avalanche of size 2 was observed on a steep alpine slope and likely released on a crust that was buried mid-February. Several small (size 1) wind slab avalanches released naturally in the alpine and at treeline. Riders triggered a small (size 1.5) wind slab on a convex roll in the alpine. The avalanche was about 30 cm deep. Warm temperatures triggered numerous small loose wet avalanches in the alpine and at treeline.

A large (size 2) slab avalanche was likely triggered by a failed cornice on Saturday. Small loose wet avalanches were reported on Friday.

Snowpack Summary

The snow surface has a crust below around 900 m on solar aspects. 40-60 cm of well settled and bonded snow sits on top of the mid-February crust. Though this layer has not produced avalanche activity, professionals in the area are still treating it with suspicion. Cornices are looming in alpine areas.

The lower snowpack is well bridged by the mid-February crust, and triggering avalanches below this layer is unlikely at this time.

Terrain and Travel

Be alert to conditions that change with elevation and wind exposure.
Minimize your exposure time below cornices.
Cornices become weak with daytime heating or solar exposure.
Remember that the snowpack will be significantly different at higher elevations than lower down.

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.