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.
Sunday night: Mostly clear, light northeast winds, alpine temperature -18 C.
Monday: Clear, light variable winds, alpine high temperature -3 C, freezing level 1500 m.
Tuesday: Increasing cloud, light northeast winds, alpine high temperature near 0 C, freezing level 1500 m.
Wednesday: Mix of sun and cloud, overnight isolated flurries with trace accumulations, light northeast winds, alpine high temperature -6 C, freezing level 1000 m.
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.
Cornices and loose wet avalanches may become more reactive with strong solar radiation and rising temperatures forecast for the coming days.
Strong easterly winds have drifted recent snow into wind slabs on lee terrain features in a reverse-loading pattern. A warming trend is forecast over the next several days, which could weaken surface snow 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.
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.
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 be possible to human trigger. Cornices may also be reaching their breaking point.
Aspects:East, South East, South, South West, West, North West.
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.
Aspects:South East, South, South West, West.
Valid until: Mar 16th, 2020 5:00PM