Wind continues to be the main driver of the avalanche danger in the region. The wind direction is expected to shift again on Friday and wind slabs should be expected on all aspects in exposed terrain.
Recent strong winds have likely formed reactive wind slabs on lee features at all elevations. Winds are expected to shift directions on Friday and therefore slabs should be expected on all aspects in exposed terrain.
Wind slabs may remain reactive to human triggers for longer than is typical due to the weak facets (sugary snow) they are sitting on.
One more day under the influence of the Arctic high pressure before a substantial storm system arrives Friday overnight. The wettest places along the coast could see upwards of 80 cm by Sunday while the north and interior parts of the region are expected to receive substantially less.
Thursday Overnight: Partly cloudy, light NW wind, treeline temperature around -22 °C.
Friday: A mix of sun and cloud, moderate to strong NW wind, treeline high around -18 °C.
Saturday: Snowfall in the south of the region 20-40 cm, strong SW wind, treeline high around -15 °C.
Sunday: Snowfall in the south of the region 20-40 cm, 5-10 cm in the north, strong to extreme SW wind, treeline high around -10 °C.
On Wednesday, a natural size 2 wind slab was observed in the alpine on a northeast aspect in the Kitimat ranges. Explosives were triggering wind slabs up to size 3 in the north of the region and up to size 2 in the south. On Tuesday, operators north of Terrace reported two size 1 wind slab avalanches; one skier-triggered, and one natural. These avalanches occurred on slopes that had been recently loaded by northerly outflow winds. Explosives were triggering wind slabs up to size 2.5 in the north of the region. On Monday, numerous natural wind slab avalanches up to size 3 were reported at treeline and above, on a variety of aspects.
Wind slabs have formed on a variety of aspects resulting from shifting winds. On Friday, the wind is expected to shift from the SE to the NW and new wind slab formation is possible. Recently formed wind slabs may remain reactive to human triggers for longer than is typical due to the weak facets (sugary snow) they are sitting on.
The early December rain crust is up to 10 cm thick, down 80-150 cm in the snowpack, and exists to an average of 1400 m in elevation. Up to 2 mm facets have been reported above this crust, and it is producing hard but sudden planar results in snowpack tests in areas north of Terrace. While this layer has generally gone dormant in the region, it still has the possibility of waking up with new snow load or warming, and wind slab avalanches may still have the potential to step down to this deeper layer in isolated areas.
