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

South Rockies.

Light snowfall amounts are expected Saturday night, with enhanced amounts in the eastern upslope areas. If you see more than 10 cm of fresh snow by Sunday, increase the danger to MODERATE, and be cautious around developing wind slabs on alpine slopes.

Confidence

Moderate - Forecast snowfall amounts are uncertain. Uncertainty is due to the limited number of field observations.

Weather Forecast

A surface low tracking across Montana is currently spilling over the region with favoured upslope flow. By Sunday, a ridge of high pressure will build over, bringing a drier day. Warmer and closer to seasonal temperatures are expected early next week.

SATURDAY NIGHT : Light snow (2-4 cm) with favoured upslope (up to 10 cm) in eastern areas / easterly wind increasing to 20-40 km/h / treeline low around -10 C / freezing level at valley bottom.

SUNDAY: Partially cloudy / localized snow accumulations (2-4 cm) / moderate southwest wind gusting at 40 km/h/ treeline high around -2 C / freezing level rising to 1600 m and back at valley bottom at night.

MONDAY: Increasing cloudiness / light to moderate southerly wind / treeline high around 0C / freezing level rising to 1800 m and remaining elevated at night.

TUESDAY: Snow at high elevation 5-15 cm / moderate southwesterly wind gusting 50 km / treeeline high around +2 C / freezing level at 1800 m.

Avalanche Summary

Observations are very limited this time of year. On Friday, small loose wet avalanches (size 1) were observed on steep rocky terrain features near Crowsnest due to strong solar input.

Check out the South Rockies field team's MIN from Friday for pictures of current conditions !

Snowpack Summary

Last week, eastern upslope areas of the region received light snow flurries accumulation each day (up to 20 cm). Recent periods of strong wind from the northeast through southeast have redistributed the recent snow in exposed high elevation terrain forming small pockets of wind slabs. A widespread and supportive melt-freeze crust, formed on April 8, is found under the recent snow and / or wind slabs. The middle and lower snowpacks are currently well settled and strong.

Terrain and Travel

Be alert to conditions that change with elevation and wind exposure.
Cornices often break further back than expected; give them a wide berth when traveling on ridgetops.
When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

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.