Avalanche Forecast
Issued: Mar 15th, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
MBender,
Avalanche Canada
Expect an upward swing in temperatures as the freezing level rises on Monday. This shift in temperature may result in an increased likelihood of triggering persistent slab avalanches. Be especially cautious underneath steep sun exposed slopes and around rock outcrops.
Summary
Confidence
Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.
Weather Forecast
SUNDAY NIGHT: Mainly clear, light northeast wind, alpine temperature -7 C.
MONDAY: Clear skies, light northwest wind, alpine temperature -3 C, freezing level 1700 m.
TUESDAY: Mix of sun and cloud, light northwest wind, alpine temperature -3 C, freezing level 1700 m.
WEDNESDAY: Mix of sun and cloud, light northeast wind, alpine temperature -4 C, freezing level 1500 m.
Avalanche Summary
Recent reports show several natural wind slab avalanches ranging in size from 1.5 to 2.5 running in the alpine on east, southeast and north aspects at treeline and in the alpine. There was also a report of a natural size 2 persistent slab avalanche in the far south of the region running on the late February surface hoar layer. This was on a southwest aspect at 1700 m and was 50 cm deep. This layer continues to surprise people with remote-triggered activity, wide propagation, and a false sense of stability from unreactive ski cuts or from multiple people moving through the terrain before an avalanche releases (see this Instagram report as a good example).
Snowpack Summary
Moderate northeast wind has redistributed the snow and formed wind slabs in exposed terrain. The recent snow may sit on a surface hoar layer and a sun crust on steep solar aspects.
A widespread weak layer of surface hoar is buried 60-120 cm deep. On solar aspects, this layer may sit over a crust. There is a low likelihood of triggering an avalanche on this layer, but the consequences of doing so would be high. Read more about surface hoar on our forecaster blog.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
- Minimize exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
Problems
Wind Slabs
Recent new snow combined with moderate northeast wind have formed wind slabs in the alpine and at exposed treeline.
Aspects: East, South East, South, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of surface hoar is buried 60-120 cm deep and is still be sensitive to triggering in specific areas. Although this problem can be found on all aspects and elevations, north to east aspects near treeline have been a hot-spot for reactivity.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 16th, 2020 5:00PM
