Avalanche Forecast

Archived

Apr 18th, 2019–Apr 21st, 2019

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Regions

Waterton Lakes.

Though the snowpack is mainly in the grips of daily spring temperature swings, a recent large avalanche failing on basal weaknesses on Mt Blackiston is a good reminder that winter remains on high north faces.

Weather Forecast

Friday: Mix of sun and cloud. West winds 50km/h gusting to 100. 5-10 mm of precipitation overnight. Freezing Level 2500m

Saturday: Scattered showers. Moderate West wind with extreme gusts. Freezing Level 1800m

Sunday: Sunny. Freezing Level 2000m

Snowpack Summary

In most areas we are seeing a typical spring snowpack with crusts breaking down in the heat of the day. The exception is high North facing terrain where temperatures have stayed cold and a winter snowpack remains, with facets continuing to linger at the base. The midpack is generally well settled.

Avalanche Summary

Forecaster observed a large avalanche on a high north facing bowl on Mount Blackiston that occurred sometime in the last week. It was triggered by cornice fall, and ran on basal weaknesses. Otherwise, no recent avalanches were observed.

Confidence

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.