Wind Slabs
N
NE
E
SE
S
SW
W
NW
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–4
Lingering wind slabs may still be reactive to human triggering. Slabs may become more reactive with daytime warming and/or sun exposure.
Avalanche forecast
View on mapNorthwest Inland
Mar 12 – 13, 2016Avalanche Canada
Archived · expired 11 years ago
Avalanche danger
Mon
Tue
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
Highlights
Lingering slabs and cornices will become weak with sun exposure. Extra caution is required on sun exposed slopes during the heat of the afternoon.
Avalanche problems
Cornices
NNEESESSWWNW- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–5
Cornices are reported to be large and weak. These could pop off at any time, but are more likely to fail with continued growth or during brief sunny breaks.
Deep Persistent Slabs
NNEESESSWWNW- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely - Possible
- Size
- 3–6
Isolated large avalanches failing on weak snow at the base of the snowpack remain a possibility. This is a greater concern during sunny breaks or with a heavy trigger like a falling cornice.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
A mix of sun and cloud is expected for Sunday with freezing levels around 1100m in the afternoon and moderate alpine winds from the south. A mix of sun and cloud is expected for Monday with the possibility of scattered flurries. Afternoon freezing levels are expected to be around 1000m and alpine winds are forecast to be light from the south. Light snowfall is currently forecast for Tuesday with freezing level around 1000m and moderate alpine wind from the southwest.
Avalanche Summary
On Friday, a two natural avalanches were reported from steep south facing terrain in the alpine north of Smithers. One was a size 1.5 and the other was a size 3. Skiers were triggering small size 1 slabs with a thickness of 10cm. In the for north, a natural size 2 cornice release was reported. On Thursday, a MIN report from Smithers (https://goo.gl/ssYcRw) describes a natural size 1.5 wind slab that released on a southeast aspect at 1600m and was 30cm thick. Natural activity was also heard but not observed from cliffy terrain in the south of the region. On Wednesday, a few natural wind slabs up to size 2.5 were observed in steep wind-loaded alpine terrain in the south of the region. There was also a large cornice fall that did not trigger a slab on the slope below. In the northern part of the region there were some reports of solar induced slabs to size 3 on south aspects, and natural cornice falls. One cornice fall triggered a size 4 avalanche that released on the ground and cleaned out an entire bowl. It was 1km wide and ran 1.5km.
Snowpack Summary
Roughly 20-40 cm of snow has fallen in the past week, with the highest accumulations occurring in the southwest of the region. Strong ridgetop winds have shifted the new snow into hard or soft wind slabs in exposed terrain, adding to an ongoing wind slab problem. A layer of surface hoar from early January can be found in isolated locations between 60 and 140 cm down. There hasn't been any activity reported on this layer for a couple of weeks now and it is becoming less of a concern. In shallower areas the snowpack sits on a weak base layer of facetted snow. Recently, this layer has been active in the north of the region, responsible for several large avalanches in unsupported alpine terrain.