Avalanche Forecast

SATURDAY NIGHT: Snow, 10-20 cm new snow, extreme southwest wind, temperature low -3 C, freezing level rising to 900 m.

SUNDAY: Snow, 10-20 cm with rain at lower elevations, extreme west wind, temperature high +1 C, freezing level at 1100 m.

MONDAY: Flurries, 10-15 cm new snow, strong southwest wind, temperature high -2 C, freezing level at 800 m.

TUESDAY: Sun, cloud, and isolated flurries, moderate gusty west wind, temperature high -5 C, freezing level at 400 m.

On Friday several small natural and explosives triggered storm slab avalanches up to size 1.5 were reported. A few natural wind slab avalanches up to size 2.5 were observed on steep alpine slopes. Overnight Friday, a natural wind slab avalanche cycle occurred from steep, lee features. 

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.

Heavy snowfall is forecasted overnight Saturday into Sunday. Wind impacting fresh snow has developed slabs in lee features. Accumulating storm snow is gaining cohesion and reactivity over firm wind scoured surfaces or a curst.

40-70 cm new snow sit on top of a variety of older snow surfaces consisting of surface hoar, facets, crust and hard wind affected layers. Previous cold temperatures promoted surface faceting and formed a 20-40 cm thick facet layer, now under fresh snow in sheltered areas. 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. 

• Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
• Storm slab size and sensitivity to triggering will likely increase through the day.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
• A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.