Avalanche Forecast
Issued: Feb 25th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
mconlan,
Avalanche Canada
Snow and strong wind are forecast. Once enough snow accumulates and forms slab properties over a buried surface hoar layer, slab avalanches will be easy to trigger by humans. Local assessment of the bond of the snow along with 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
TUESDAY NIGHT: Cloudy with light snowfall, accumulation 2 to 5 cm, moderate southwest wind, alpine temperature -7 C.
WEDNESDAY: Morning snowfall then a mix of sun and cloud, accumulation 5 to 10 cm, moderate to strong west wind, alpine temperature -8 C, freezing level rising to 1000 m.
THURSDAY: Morning snowfall then a mix of sun and cloud, accumulation 2 to 5 cm, light to moderate southwest wind, alpine temperature -6 C, freezing level rising to 1500 m.
FRIDAY: Morning snowfall then a mix of sun and cloud, accumulation 2 to 5 cm, light southwest wind, alpine temperature -5 C, freezing level 1500 m.
Avalanche Summary
On Monday, a few small wind slab avalanches were reactive to human activity. They were on northerly aspects, 15 to 20 cm deep, and at treeline and alpine elevations. Otherwise, loose snow was reactive in steep terrain.
Snowpack Summary
Around 20 to 40 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. The new snow will likely become increasingly reactive to human triggers as it stacks up and settles into a cohesive slab.
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
Storm Slabs
Snowfall continues to load a widespread layer of surface hoar found at all elevations. On solar aspects the surface hoar is sitting on a crust, which is a particularly nasty combination. There is currently 20 to 40 cm of snow that overlies it and another 5 to 15 cm of snow is forecast until Wednesday afternoon. This problem will become reactive once enough snowfall has accumulated and slab properties form. There is uncertainty on when exactly this will occur, so you should travel conservatively and assess this layer before committing to avalanche terrain. Also be aware that snowfall is occurring with strong southwest wind, which will load lee terrain features near ridges quickly.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 26th, 2020 5:00PM
