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Avalanche Forecast

Archived

Mar 26th, 2022–Mar 27th, 2022

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Kootenay Boundary.

Warm temperature and sunshine will destabilize the snowpack throughout the day, especially on steep slopes that are baking in the sun. Timing, thoughtful terrain choices and conservative decision-making are essential for safe travel in the backcountry.

Confidence

Moderate - The snowpack structure is generally well understood. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast. Uncertainty is due to the fact that cornice falls are particularly difficult to forecast.

Weather Forecast

A frontal wave draped across southern B.C. will keep the southeast regions mostly dry for Sunday.

SATURDAY NIGHT: Mainly cloudy. No precipitation. 10-15 km/h southerly winds. Low alpine temperature 0 C with freezing level around 2200 m.

SUNDAY: Cloudy with sunny periods. No precipitation. 10-15 km/h southerly winds. High alpine temperature +8 C with freezing level around 2700 m.

MONDAY: Cloudy with sunny periods and isolated showers. Trace of precipitation. 15-25 km/h southwesterly winds. High alpine temperature +6 C with freezing level around 2200 m.

TUESDAY: A mix of sun and cloud. No precipitation. 15-20 km/h northeasterly winds. Hig alpine temperature +4 C with freezing level around 2000 m.

Avalanche Summary

On Friday, a large (size 3) avalanche was remotely triggered by a vehicule on an east facing slope around treeline and the low alpine. It may have started as a small avalanche that stepped down to deeper preserved buried surface hoar from late January and early March.

Also, numerous loose wet and wet slab avalanches up to size 2.5 were triggered by explosives on solar aspects.

Snowpack Summary

Recent snow and moderate wind have formed small isolated pockets of windslab in the high alpine. Refrozen crust on all aspects as high as 2500 m, softening in the afternoon at low elevations and on steep, sunny slopes. Recent warm temperatures, sun, and rain have made the top 10-30 cm of the snowpack moist. At very low elevations, the snowpack may be wet and isothermal, depending on overnight freezing levels. 

40 to 70 cm below the snow surface, you'll find a frozen sun crust on solar aspects, and weak, feathery surface hoar crystals on shaded aspects. This layer was buried in early March. During the last storm, and on the warmest days earlier this week, it produced surprising avalanches in the Selkirks (east side of the region). The recent warm weather may help this layer bond in the long run, but it's not yet time to take it out of your danger assessment for the day.

The mid and lower snowpack are generally strong and well bonded.

Terrain and Travel

  • Be alert to conditions that change with aspect and elevation.
  • As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.