Avalanche Forecast
Issued: Mar 14th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Loose Wet.
astclair,
Avalanche Canada
Strong northeast winds have formed wind slabs on atypical slopes. Sunny skies and a warming trend could start to weaken sun-exposed slopes and cornices.
Summary
Confidence
Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.
Weather Forecast
Saturday night: Decreasing cloud, light northeast winds, alpine temperature -23 C.
Sunday: Mostly clear, light northeast winds, alpine high temperature -8 C.Â
Monday: Clear, light northeast winds, alpine high temperature -3 C, freezing level 1300 m.
Tuesday: Mostly clear, light northeast winds, alpine high temperature near 0 C, freezing level 2000 m.
Avalanche Summary
Several large (size 2) wind slabs were reported on Saturday releasing naturally on lee slopes above 1700 m. Numerous small (size 1) wind slabs were also reported as a result of ski cuts.
Cornices have grown large with the recent weather, and a cornice failure could trigger a wind slab avalanche on the slope below. On Friday, there were reports of cornice falls triggering small wind slab avalanches.Â
Over the past few days, there have been several reports of natural, human-triggered, and explosive-triggered avalanches releasing in the previous storm snow, primarily on lee aspects above 1900 m. These avalanches were small to large (size 1.5-2), breaking 20-60 cm deep, and in a few cases, triggered by cornice falls.
Avalanches are expected to become more reactive with a significant warm-up forecast for the coming days.
Snowpack Summary
Strong easterly winds have drifted recent snow into wind slabs on lee terrain features in a reverse-loading pattern. A major warming trend is forecast over the next several days, which could rapidly weaken the snowpack and cornices.
A total of 30 to 60 cm of snow from the previous storm has been redistributed by wind or is well-settled. This snow sits over another layer of buried wind slabs in exposed areas and a sun crust on solar aspects (south through west facing slopes). Melt-freeze crusts extend up to 1900 m on other aspects.Â
A thick crust/facet layer currently sits 30-60 cm below the surface. There has been only one avalanche reported on this layer since February 17th. The middle of the snowpack is generally strong, but the base of the snowpack contains weak 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.
Problems
Wind Slabs
Strong easterly winds have drifted available snow into wind slabs on lee terrain features. This wind direction is atypical, so you may find wind slabs in terrain features that don't typically have them.
Aspects: East, South East, South, South West, West, North West.
Elevations: All elevations.
Likelihood
Expected Size
Loose Wet
Rapidly rising temperatures and intense solar radiation may initiate wet loose avalanches and weaken cornices. This activity is likely to be most prominent on steep slopes that receive direct day-time solar radiation (slopes that face south through west). Minimize exposure to steep, sun-exposed slopes and cornices on Sunday.
Aspects: South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 15th, 2020 5:00PM
