Avalanche Forecast
Issued: Mar 2nd, 2020 3:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
ahanna,
Avalanche Canada
Between fresh wind slabs and a touchy persistent weak layer, human triggered avalanches are very likely. Keep in mind it's not always the first rider who triggers the slab.
Summary
Confidence
Weather Forecast
Monday night: 5-10 cm new snow. Strong west wind, extreme at ridgetop. Freezing level 1300 m.
Tuesday: Isolated flurries bringing a trace of new snow. Moderate west wind. Freezing level 1000 m.
Wednesday: 5-10 cm new snow. Moderate west wind. Freezing level 1000 m.
Thursday: 5-10 cm new snow. Moderate southwest wind. Freezing level 1500 m.
Avalanche Summary
Over the last few days, persistent slab avalanches were reported, running on the surface hoar layer. Skier triggered size 1-2 on north to east aspects in the alpine, and natural size 2-3 in steep alpine terrain with a few size 2 observed below treeline. Natural wind and storm slabs size 1.5-3 were observed on north to east aspects in the alpine on Sunday.
Snowpack Summary
Light snowfall and strong winds are building fresh wind slabs in the alpine and open areas at treeline.
A weak layer of widespread surface hoar sits 60-80 cm deep, ontop of a crust on solar aspects. The overlying snow has been cohered into slabs by incremental loading through successive storms, wind and mild temperatures. As slab character and depth increase, so do reactivity and size of avalanches failing on the weak layer. Read more about surface hoar on our forecaster blog! There is uncertainty about the distribution of this layer in the north of the region.
Terrain and Travel
- Stick to simple terrain or small features with limited consequence.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
Problems
Wind Slabs
Strong southwest wind has formed wind slabs in exposed terrain. Use added caution in lee terrain features, particularly near ridges.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of surface hoar sits 60-80 cm deep. The overlying snow has been cohered into slabs by incremental loading through successive storms, wind at upper elevations and mild temperatures at lower elevations. As slab character increases, so do reactivity and size of avalanches failing on the weak layer (surface hoar). Read more about surface hoar on our forecaster blog!
Skier triggering of these persistent slabs is likely, and has be observed over the last few days even as professionals seek to actively avoid suspect terrain features (eg. convex rolls). Observations are concentrated on north to east aspects around treeline.
This problem has been observed mostly in the south of the region. There is uncertainty around the distribution of the surface hoar problem in the north.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 3rd, 2020 5:00PM
