Avalanche Forecast
Issued: Apr 23rd, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
wlewis,
Avalanche Canada
High daytime freezing levels and mild overnight temperatures will stress the snowpack, with the greatest hazard for thin snowpack areas where buried crusts and weak layers may become reactive.
Stick to conservative, low angle, and supported terrain features. Avoid overhead hazard during peak warming and sunshine.
Summary
Confidence
Moderate
Avalanche Summary
Observations are limited at this point in the season. If you have any observations, let us know what you are seeing through the Mountain Information Network.
Loose snow avalanches have been observed throughout the week as the sun weakens the surface snow.
Recent avalanche activity in adjacent forecast areas highlights the need to avoid rocky and thin snowpack areas for the remainder of the season. A fatal size 3 was reported from the Lake Louise area on April 22nd, in a particularly thin and rocky area with a 50 cm deep snowpack. All information can be found here.
Snowpack Summary
Mild temperatures and sunshine have created a surface crust that exists on all aspects on sun-affected slopes and into the alpine on shaded slopes. Moist snow likely remains at low elevations on all aspects.
Around 20-50 cm deep, a thick melt-freeze crust is found up to 2200 m. As temperatures increase this will become a concern for avalanche activity.
The mid snowpack is generally settled and strong at treeline and above. The exception is areas where snow depths measure less than 150 cm. In these thin areas, the mid-pack is likely weaker and more faceted.
A weak layer of large, sugary crystals persists at the base of the snowpack. This layer has not produced recent avalanche activity in these areas, but it is a concern as warming affects the snowpack - particularly in thin and rocky snowpack areas.
Weather Summary
Sunday Night
Mostly cloudy. Light snowfall delivers around 5-10 cm. Light westerly wind. Freezing levels remain above 1500 m overnight.
Monday
Cloudy with light westerly winds. Isolated flurries may deliver up to 10 cm in localised areas. Freezing levels reach 2200 m, so expect mixed precipitation or rain below.
Tuesday
A mix of sun and cloud with light westerly winds. No snowfall is expected. Freezing levels rise to 2200m.
Wednesday
Mostly clear skies with moderate westerly winds. No snowfall expected.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
Problems
Wind Slabs
Southwest winds are expected to have formed fresh wind slabs on north and east-facing slopes at treeline and above. Watch for wind loading as you transition to and from ridgeline features.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Multiple crusts exist throughout the snowpack that may form ideal sliding layers for avalanche activity as warm temperatures weaken the snowpack.
The base of the snowpack remains weak. Particularly in thin snowpack areas, prolonged warming may increase the likelihood of avalanche activity on this layer. Uncertainty is high around how this layer will react to this warm weather and whether it will reach the tipping point for large avalanche activity.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 24th, 2023 4:00PM
