Avalanche Forecast
Issued: Mar 16th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Wet and Deep Persistent Slabs.
JSmith,
Avalanche Canada
Lingering wind slabs below ridgetops may remain reactive to human triggers. Strong solar radiation weakens cornices and often causes them to fall onto slopes and trigger large avalanches. Pay attention to what's above your head if the sun is out.
Summary
Confidence
Moderate - Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.
Weather Forecast
Monday night: Clear, Moderate northwest winds, alpine low -12 C, freezing level valley bottom.
Tuesday: Sunny, light east winds, alpine high 0 C, freezing level 1700 m.
Wednesday: Sunny, light to moderate northwest winds, alpine high -4 C, freezing level valley bottom.
Thursday: Sunny, light west winds, alpine high -7 C, freezing level valley bottom.
Avalanche Summary
Numerous small (size 1-1.5) wind slabs were reported on Saturday failing both naturally and from human and explosive triggers. Cornices have grown large with the recent weather, and a cornice failure could trigger a large slab avalanche on the slope below.Â
Snowpack Summary
Recent strong easterly winds created fresh wind slabs on lee terrain features in a reverse-loading pattern.
A thick crust/facet layer currently sits 40-80 cm below the surface and can be found up to 2100 m. The middle of the snowpack is generally strong, but the base of the snowpack contains basal facets that are most prominent in shallow rocky start zones.
Terrain and Travel
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Be aware of the potential for large avalanches due to the presence of a deep persistent slab.
Problems
Wind Slabs
Strong easterly winds have drifted the 10-20 cm of new snow into wind slabs on lee terrain features in a reverse loading pattern. These wind slabs may remain possible to human trigger. Cornices may also be reaching their breaking point.
Aspects: East, South East, South, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Strong solar radiation may trigger a natural wet loose avalanche cycle on steep solar aspects.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Weak snow at the bottom of the snowpack hasn't gone away. Evidence of deep persistent slab avalanches has been focused in the Sparwood-Elkford area over the past month. Human triggering is most likely around steep rocky terrain features or anywhere the snowpack is thin and weak. Cornices have grown large and loom over many ridge lines. A failing cornice could initiate a deep persistent slab when it impacts the slope below.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 17th, 2020 5:00PM
