Avalanche Forecast

Archived

Apr 5th, 2025–Apr 6th, 2025

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 possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

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.

Regions

Purcells, Dogtooth, East Purcell, West Purcell.

Avalanche danger is expected to increase throughout the day.

Surface instabilities or large cornice falls may step down to deeper persistent weak layers.

Read the new forecasters' blog.

Confidence

Moderate

Avalanche Summary

On Friday, a natural cornice fall pulled a slab (size 2.5) on a northeasterly alpine slope. Several wet loose avalanches were solar-triggered on steep southerly slopes throughout the region.

Natural persistent slab activity occurred from thin rocky northerly terrain near Panorama on Thursday. Several dry loose and wind slabs were reactive to skier traffic in the region.

Expect increasing avalanche activity within the recent snow with the forecasted warm weather.

Snowpack Summary

A spring diurnal cycle occurred up to 2000 m. The surface is either moist or capped with a thin crust on all aspects and elevations except for high northerly slopes where up to 30 cm of settled snow overlies a thick crust from late March.

Several weak layers from early March, mid-February and late January can be found in the mid and lower snowpack. These layers remain a concern where a thick crust isn’t present above.

The base of the snowpack is generally faceted.

Weather Summary

Saturday Night

Clear. 10 to 20 km/h west ridgetop wind. Treeline temperature -2 °C. Freezing level around 1500 m with temperature inversion.

Sunday

Sunny. 10 to 20 km/h southeast ridgetop wind. Treeline temperature +6 °C. Freezing level rising to 3000 m.

Monday

Mix of sun and clouds. 30 to 50 km/h south ridgetop wind. Treeline temperature +4 °C. Freezing level lowering to 2500 m.

Tuesday

Cloudy with isolated flurries. 20 to 30 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level around 2000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avalanche danger is expected to increase throughout the day.
Avoid areas with a thin or variable snowpack.
The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
Limit exposure to steep, sun exposed slopes, especially when the solar radiation is strong.

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.