Choose mellow, low-consequence slopes and give the snowpack time to adjust to the new load. Uncertainty about deeper weak layers demands vigilance and careful terrain selection.
Triggering persistent slab avalanches remains possible due to several weak layers in the top metre of the snowpack. Facet layers are the primary concern in alpine terrain, while preserved surface hoar layers are the concern in treeline terrain.
Avalanches that start as storm slabs may step down to these deeper layers.
Overnight snowfall will continue throughout the morning forming fresh and reactive storm slabs. Expect the deepest and most reactive slabs to exist in wind-loaded terrain at upper elevations.
On Monday, several large (size 2-3) persistent slab avalanches occurred with explosive control in the south of the region. These avalanches failed on a weak facet layer formed in late December.
Several skier-triggered (size 1-2) persistent slab avalanches have been reported around Terrace and Smithers over the past few days. These avalanches are failing on a weak layer of surface hoar in the upper meter of the snowpack. One of these slabs stepped down to a layer of weak, sugary, facetted crystals that were buried on December 23rd.
Fresh snow will be falling mostly on 20-50 cm of settled snow. In sheltered areas, a layer of weak, feathery surface hoar crystals buried in early January will now be 40-70 cm below the surface. Expect a shallower, weaker snowpack in wind-exposed terrain.
Several persistent weak layers may be found in the top meter of the snowpack. These include a surface hoar layer buried on Jan 9th, now 20 to 40 cm deep, Dec 28 found 40 to 80 cm deep and a facet layer buried on Dec 23 found 60 to 100 cm deep. In alpine terrain, triggering one of these layers is most likely on steep rocky slopes where they present as facets. In treeline terrain, the layers are most likely triggered on steep slopes in open trees where they present as preserved surface hoar.
Tuesday night
Cloudy with snowfall, 5 to 20 cm of accumulation. Alpine temperatures drop to a low of -6 °C. Ridge wind southeast 40-50 km/h. Freezing level 500 metres.
Wednesday
Cloudy with flurries in the morning and sunny breaks in the afternoon. Accumulation 2 to 10 cm. Alpine temperatures reach a high of -6 °C. Ridge wind west 30 km/h gusting to 55 km/h. Freezing level 700 metres.
ThursdayMainly cloudy with scattered flurries. 5 to 10 cm accumulation. Alpine temperatures reach a high of -4 °C. Ridge wind southwest 35 km/h gusting to 60 km/h. Freezing level rises to 1300 metres.
FridayCloudy with scattered flurries, 5 to 15 cm accumulation Alpine temperatures reach a high of -2 °C. Ridge wind southwest 45 km/h gusting to 75 km/h. Freezing level rises to 1100 metres.
More details can be found in the Mountain Weather Forecast.
