Avalanche Forecast
Issued: Feb 26th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
mconlan,
Avalanche Canada
Snow, wind, and warming are forecast. Slab avalanches will be easy to trigger once recent snow forms slab properties over a buried surface hoar layer. Assessing for slab properties and conservative decision-making are recommended tactics.
Summary
Confidence
Moderate - Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather.
Weather Forecast
WEDNESDAY NIGHT: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong west wind, alpine temperature -6 C, freezing level 1000 m.
THURSDAY: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong southwest wind, alpine temperature -5 C, freezing level rising to 1400 m.
FRIDAY: Cloudy with snowfall, accumulation 5 to 10 cm, light southwest wind, alpine temperature -5 C, freezing level 1500 m.
SATURDAY: Cloudy with snowfall, accumulation 5 to 10 cm, light southwest wind, alpine temperature -7 C, freezing level 1000 m.
Avalanche Summary
Some areas of the region saw no avalanche activity and other areas saw natural and human-triggered avalanche activity in the recent storm snow. The avalanches were small (size 1 to 1.5) and occurred around treeline and lower alpine elevations. Some of the avalanches were releasing on the surface hoar described in the Snowpack Summary.
Snowpack Summary
Around 30 to 50 cm of snow overlies a widespread layer of surface hoar that was reported to be between 5 and 15 mm in size. This layer exists on all aspects and elevations except for steep, sun-exposed aspects where it was melted by sun and formed a melt-freeze crust. Surface hoar sitting on a thin sun crust may exist on lower angle solar aspects, which is a particularly nasty combination. So far, the overlying snow has been reactive to human activity where the wind has redistributed it, forming a slab. This has been most common around treeline and alpine elevations.
The mid and lower snowpack is generally well-settled and strong.
Terrain and Travel
- Stick to simple terrain or small features with limited consequence.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid terrain traps such as gullies and cliffs where the consequence of any avalanche could be serious.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
Problems
Persistent Slabs
Snowfall continues to load a widespread layer of surface hoar found at all elevations. The surface hoar is sitting on a crust on sun-exposed slopes, which is a particularly nasty combination. There is currently 30 to 50 cm of snow that overlies it and another 10 to 20 cm of snow is forecast until Thursday afternoon. This problem will become reactive once enough snowfall has accumulated and slab properties form. So far, the layer has been most reactive at treeline and alpine elevations, where the recent snow has been redistributed by the wind.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 27th, 2020 5:00PM
