Avalanche Forecast
Issued: Mar 2nd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Deep Persistent Slabs.
ahanna,
Avalanche Canada
The snowiest parts of the region are now approaching critical loading of a buried weak layer which is becoming reactive, especially to human triggers. In drier parts of the region be mindful that deep wind loaded pockets are sitting on this weak layer.
Summary
Confidence
Weather Forecast
Monday night: Flurries bringing up to 5 cm new snow. Strong northwest wind. Freezing level 1400 m.
Tuesday: Mix of sun and cloud with flurries starting in the afternoon. Moderate northwest wind. Freezing level 1500 m.
Wednesday: 5-15 cm new snow. Moderate west wind. Freezing level 1200 m.
Thursday: Flurries. Moderate southwest wind. Freezing level 1700 m.
Avalanche Summary
Persistent slab avalanche activity is starting to pick up in the west of the region, were snowfall amounts have been greatest over the surface hoar layer which is now reaching a tipping point. In this part of the region on Sunday, skier accidental persistent slabs size 1-2 were reported on east aspects treeline and below. Heli remotes were reported up to size 2.5. Natural persistent slabs 2-3 were observed on south aspects around treeline.
Over the weekend, natural, skier and snowmobile triggered storm and wind slab avalanches were reported size 1-2. A size 2.5 failed down to glacial ice and ran to valley bottom.
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 20-50 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!
Deep basal facets lurk near the bottom of the snowpack. This layer has been responsible for occasional and hard-to-predict deep persistent slab avalanches usually triggered from shallow, rocky start zones.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Wind Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of surface hoar sits 20-40 cm deep. So far, the layer has been most reactive at treeline and alpine elevations in the deeper snowpack areas in the west of the forecast region. Avalanche activity on this layer is expected to increase as it approaches critical loading by new snow and wind forecast later in the week. Read more about surface hoar on our forecaster blog!
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Weak snow at the bottom of the snowpack continues to pose a deep persistent slab avalanche problem. Treat wind scoured, rocky, shallow terrain as suspect. Also avoid big alpine slopes that are threatened by cornices overhead.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 3rd, 2020 5:00PM
