Forecast snowfall amounts in the south of the region near Coquihalla pass are uncertain Tuesday night. If overnight snowfall exceeds 25 cm, expect the avalanche danger to be HIGH.
A couple of problematic layers may be found around 80 to 180 cm deep, including weak layers of surface hoar and faceted grains above a hard melt-freeze crust. With the addition of a significant load of new snow, large avalanches may run naturally on these layers. This problem seems to be most prevalent in the north of the region around Duffy Lake.
Overnight snowfall combined with wind has possibly created reactive storm slabs in the south of the region. Deepest deposits can be found in lee terrain with forecast strong to extreme southwest wind.
Tuesday Night: Heavy snowfall above 1100m in the Coquihalla area with accumulations of 20-40 cm. Snow accumulation in the north of the region expected to be 5-15 cm. Strong southwest wind, alpine high -2, freezing level 1300 m.
Wednesday: Mainly cloudy, southwest wind easing to light, alpine high -2, freezing level 1300 m.
Thursday: Sun and cloud, light t moderate south wind, alpine high -3, freezing level 1100 m.
Friday night: Flurries, up to 5 cm, moderate to strong southwest wind, freezing level 700 m.
No avalanches were reported Monday and Tuesday. Over the weekend, a large natural storm slab avalanche cycle was observed up to size 3 in much of the region and up to size 4 near Pemberton.
Persistent slab avalanche activity has tapered significantly since the cycle early last week, but persistent slabs size 2-2.5 were still triggerable by explosives on weekend.
Over 70 cm of recent snow has seen extensive wind affect at upper elevations, with scoured windward aspects, wind slabs in lee features and growing cornices at ridgetop. In sheltered areas below treeline, recent snow may be sitting on surface hoar.
A melt-freeze crust from early December is found around 80 to 180 cm deep in the snowpack. This crust may have surface hoar or sugary faceted grains sitting above it. This persistent weak layer is most prevalent in the north (e.g., Duffey Lake, Hurley) and found to a lesser extent in the south of the region.
The remainder of the snowpack is generally well settled.
