Avalanche Forecast
Regions: Dogtooth, East Purcell, Purcells.
Avoid being in or under avalanche terrain.
Intense spring sun and rising temperatures have increased the risk of large natural and rider-triggered avalanches.
Confidence
High
Avalanche Summary
Thursday, several loose wet avalanches, a large (size 2.5) naturally triggered persistent slab and a skier-triggered avalanche were observed. (See photos)
Wednesday, west of Golden, a large, human-triggered persistent slab avalanche was reported. This avalanche was triggered on a ridge crest that had been previously ski-cut.
Looking forward, we are expecting persistent avalanche problems to become worse with rising temperatures and intense spring sun.
Snowpack Summary
During the day, frozen and crusty surface snow will melt and turn moist or slushy due to high freezing levels combined with intense sun. This will be especially prevalent on sunny slopes and at lower elevations. This will cause the avalanche hazard to rise as the day warms. High-elevation shady north-facing slopes may still have some dry snow.
A widespread crust is buried roughly 80-120 cm deep. Weak faceted crystals and surface hoar above this crust are contributing to large avalanches across the province and continue to be the primary layer of concern here.
The basal snowpack is generally weak and faceted, with the potential to produce very large avalanches with the forecast of prolonged warming.
Weather Summary
Friday Night
Mostly clear. No new snow expected. 15 km/h northwest ridgetop wind. Treeline temperature around 0 °C. Freezing level around 2900 m with a potential temperature inversion below 1800 m.
Saturday
Sunny. No new snow expected. 10 km/h northwest ridgetop wind. Treeline high around 7 °C. Freezing level around 3000 m with a overnight temperature inversion below 1800 m.
Sunday
Sunny. No new snow expected. 5 km/h variable ridgetop wind. Treeline high around 8 °C. Freezing level rising to 3200 m.
Monday
Mostly sunny. No new snow expected. 5 km/h east ridgetop wind. Treeline high around 8 °C. Freezing level rising to 3300 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Only the most simple non-avalanche terrain free of overhead hazard is appropriate at this time.
- Be aware of the potential for large, deep avalanches to run full path or even longer.
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
- As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
Avalanche Problems
Persistent Slabs
We expect persistent weak layers to become more reactive as the temperature increases. Cornices are also weakening, and large falling cornice chunks could trigger an even bigger avalanche.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 2 - 3.5
Loose Wet
Freezing levels are rising, and the spring sun packs a punch. The chance of loose wet avalanches will increase throughout the day.
Aspects: East, South East, South, South West, West, North West.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2.5
Deep Persistent Slabs
The basal snowpack remains generally weak, especially at higher elevations where a protective crust above may not exist. Loose wet avalanches or falling cornices may have the potential to trigger this deep layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 2 - 4