Avalanche Forecast
Northwest Coastal
Watch for signs of instability at upper elevations and be cautious around steep convex slopes where wind slabs or buried surface hoar could be reactive to human triggers.
Avalanche Problem 1: Wind Slabs
What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?
Travel and Terrain Advice
- Use caution in lee areas. Recent wind loading has created deep slabs.
- Use caution on open slopes and convex rolls at treeline where buried surface hoar may be preserved.
- Watch for signs of instability such as whumpfing, hollow sounds, or cracking.
Avalanche Summary
On Saturday, a few small size 1 avalanches were triggered by skiers on a 20 cm deep surface hoar layer at treeline elevations.
Reports of a widespread natural avalanche cycle that occurred last week continue to come in. This cycle produced numerous size 2-3 storm slab avalanches and a few very large historic avalanches (size 4+) in deeply wind-loaded areas along the Skeena corridor near Terrace. Following the natural activity, explosive control on Thursday produced more large and very large avalanches, but by Friday explosive testing produced mostly small avalanches with the exception of one explosive-controlled cornice that triggered a size 2.5 slab down to the base of the snowpack in a thin snowpack area.
Snowpack Summary
Strong outflow winds have scoured and redistributed storm snow accumulations of 50-70 cm into deep wind slabs on a variety of aspects in wind-exposed terrain. In sheltered areas at treeline and below, 20-30 cm of settling snow sits over a layer of surface hoar that has been reactive to skier traffic.
A few deeper interfaces may have been reactive during the recent storm, but have become much harder to trigger since. These include layers of sun crust, facets, and isolated surface hoar buried 70-150 cm below the surface. Deeper in the snowpack, around 150-200 cm down, you'll find a crust/surface hoar layer from January which still has the potential to be triggered from a thin snowpack spot, or with a large trigger like cornice fall. Basal facets may be found near the bottom of the snowpack in colder and drier parts of the region, such as in the far north.
Weather Forecast
MONDAY: Mainly cloudy with isolated flurries and a trace of new snow, moderate northwest winds, alpine high temperatures around -10 C.
TUESDAY: Cloudy with increasing flurries bringing about 3 cm of new snow, light to moderate south wind, alpine high temperatures around -8 C.
WEDNESDAY: Mix of sun and cloud, light wind, alpine high temperatures around -6 C.
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Strong winds have redistributed snow into wind slabs on all aspects. A surface hoar layer 20 cm below the surface has been reactive to skiers at treeline elevations and could potentially produce larger avalanches on isolated wind-loaded slopes.