Avalanche Forecast

Archived

Apr 16th, 2022–Apr 17th, 2022

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

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

Purcells.

Large cornices are hard to pinpoint when travelling on a ridge top and can be easily triggered by the weight of a person; so stay well back. Looking at approaching big lines? Make sure to read this new blog.

Confidence

Moderate - Uncertainty is due to the limited number of field observations. Confidence is due to a stable weather pattern with little change expected.

Weather Forecast

A surface low tracking across Montana is spilling over the south part of the region tonight. By Sunday, a weak ridge of high pressure will build over, brining a drier day. Early next week, a low-pressure system from the BC Coast will bring light to moderate precipitation into the interior ranges.

SATURDAY NIGHT: 3-5 cm localized accumulations / light variable wind / treeline low around -10 C / freezing level at valley bottom.

SUNDAY: Partially cloudy / scattered localized flurries / light west wind / treeline high around -2 C / freezing level rising to 1600 m and back at valley bottom at night.

MONDAY: Increasing cloudiness / continued precipitation starting midday and continuing overnight total 5-10 cm / moderate south wind gusting 40 km/h / treeline high of +1 C / freezing level rising to 1800 m and remaining elevated at night.

TUESDAY: Snow 5-10 cm / moderate southwesterly winds gusting 50 km/h / treeline high around +3C/ freezing level around to 2100 m.

Avalanche Summary

Observations are limited this time of year. No new avalanches were reported in the last 24 hours.

If you are getting out in the backcountry, please consider contributing to the Mountain Information Network by sharing snow / riding conditions.

Snowpack Summary

10-30 cm of snow sits over a widespread melt-freeze crust formed on April 8. Periods of strong wind earlier this week have redistributed this snow in exposed terrain

forming wind slabs or hard wind pressed surfaces. Cornices have grown large recently, but are expected to be relatively stable with the current cold temperatures. A sun crust has formed on steep sun-exposed slopes.

A thick rain crust with facets above from early December is buried around 100-200 cm deep. Large avalanches were naturally triggered on this layer during the last significant warming event in the western part of the region near the Bugaboos. Although not a concern for the weekend, we expect it will wake up again with the next major input of warming and sun, or rainfall.

Terrain and Travel

When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Carefully evaluate steep lines for wind slabs.

Problems

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.