Avalanche Forecast
Issued: Mar 14th, 2021 3:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Loose Wet and Cornices.
jcoulter,
Avalanche Canada
Less solar input is expected on Monday, but some elevation bands may not get a good overnight re-freeze. Move off slopes before they get wet or slushy. Consecutive days in a row of warm temperatures may increase the reactivity of deeper weak layers and cornices.
Summary
Confidence
Moderate - Uncertainty is due to difficult to forecast freezing levels. Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather.
Weather Forecast
SUNDAY NIGHT: Partly cloudy, light to moderate southwest wind, alpine low -2 C, freezing level dropping to 1700-1800 m. Potential for near freezing layer developing at surface.
MONDAY: Increasing cloud, flurries/light rain possible, 0-5 mm, light easterly wind, alpine high 0 C, freezing level 1800-2000 m.Â
TUESDAY: Mostly sunny, light west wind, alpine high +2, freezing level 2200 m.
WEDNESDAY: Sunny, light south west wind, alpine high +2, freezing level 2200 m.
Avalanche Summary
A small (size 1) wind slab was triggered accidentally near Fernie on Saturday. The weekend also included reports of wet loose avalanches from size 1-2. On Thursday-Friday a few solar triggered slabs up to size 2 were noted.
Snowpack Summary
Wind slabs in the alpine may linger, especially on northerly aspects. Snow on all solar aspects and elevation bands has been getting moist by mid morning and may not be getting a good overnight re-freeze of late. Snow on north facing terrain above 1500 m has so far remained dry, but this could change on Monday depending on the snow rain line and freezing levels. Cornices are large and looming, and glide cracks are increasing in size...both should be considered unpredictable and given a wide berth.
Around 30 to 50 cm of snow overlies a variety of old interfaces that formed in mid-February. There hasn't been recent avalanche activity on this layer, but it remains on the radar, especially in alpine terrain as things stay warm. The more active layer was buried late January, which is found 50 to 100 cm deep. This layer is mostly composed of sugary faceted grains or feathery surface hoar crystals. In specific terrain features the layer is still producing snowpack test results causing some concern for low probability high consequence avalanches, especially in this period of warming.Â
Terrain and Travel
- Be alert to conditions that change with aspect and elevation.
- Cornices become weak with daytime heating or solar exposure.
- Cornices often break further back than expected; give them a wide berth when traveling on ridgetops.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Be alert to conditions that change throughout the day.
Problems
Persistent Slabs
Consecutive days of warm temperatures without a solid overnight re-freeze may reactivate persistent weak layers from January and February. Widespread avalanche activity has already occurred on the layers, but they could still be triggered anywhere they haven't already failed. Look for signs of instability and continue treating the snowpack as suspect if you are uncertain whether the layer is still present in your riding area.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Sunny breaks, warm temperatures and potential light rain may weaken the upper snowpack and form wet loose avalanches, especially if we don't get a good overnight re-freeze. Pinwheeling and a moist snow surface are signs that the stability of the upper snowpack is decreasing.
Even small avalanches can be a hazard in high consequence terrain and above terrain traps.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices are large and likely weakening with sustained elevated freezing levels and significant daytime heating. Big cornice falls are a hazard on their own but can also trigger large persistent slab avalanches on the slopes below.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 15th, 2021 4:00PM
