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RegisterFeb 18th, 2021–Feb 19th, 2021
Northwest Coastal.
20-30 cm new snow by the end of the day on Friday combined with strong southwest wind will increase the avalanche danger quickly throughout the day. The storm and wind slabs will be most reactive where they sit on cold facets, surface hoar and hard wind affected surfaces.
THURSDAY NIGHT: Cloudy, 10-15 cm new snow and up to 30 cm in the very south of the region, strong southwest wind, temperature low -5 C.
FRIDAY: Cloudy, 10-15 cm new snow, strong southwest wind, temperature high -3 C, freezing level at 700 m.
SATURDAY: Cloudy, 15-20 cm new snow, strong to extreme southwest wind, temperature high 0 C, freezing level rising to 900 m.
SUNDAY: Cloudy, 25-35 cm new snow, strong southwest wind, temperature high +1 C, freezing level at 1000 m.
Whumpfing was reported by a party on Wednesday (see this MIN report). Many natural wind slab avalanches of size 2-2.5 were observed on lee terrain features and cross-loaded slopes. Several small dry and wet loose avalanches were reported on steep solar aspects. Several dry loose avalanches up to size 2.5 on steep terrain were reported on Tuesday.
Natural wind slabs to size 2 have been reported on various wind loaded and cross loaded aspects over the weekend. These wind slabs were formed by the recent outflow winds. Wind slabs have also been reactive to human triggering with ski cuts in the size 1-1.5 range.
On Saturday explosives control triggered cornice and wind slabs, mostly size 1-2 with the odd larger result with big cornices.
It is worth remembering that skiers were able to trigger unsupported pillows failing on surface hoar down 25-40 cm near Terrace last week. Although there are no recent reports of avalanches failing on this layer, it is still propagating in some snowpack tests and this layer might become reactive with the increasing snow load.
20-40 cm of recent snow sit on top of a variety of older snow surfaces consisting of facets and crust, hard wind slabs, scoured slopes and sastrugi. Below treeline, 20-50 cm of soft snow sits above isolated pockets of surface hoar and a crust which is more prominent on solar aspects. The late January interface is down 40-80 cm and consists of surface hoar in sheltered locations, a crust on solar aspects, and facets and stiff wind affected snow at upper elevations.
The mid-pack seems to be well settled. Deep persistent layers appear to have mostly become unreactive, except for the Bear Pass area and the far reaches south of Kitimat.