Regions
Northwest Coastal.
The sun can pack a punch this time of year. Be aware of signs of deteriorating stability such as snow pin-wheeling down slopes or small point-release avalanching below cliffs.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
WEDNESDAY: Mix of sun and cloud / Light northwesterly ridgetop winds / Alpine high of -4THURSDAY: Mix of sun and cloud / Light to moderate southwesterly ridgetop winds / Alpine high of -4 FRIDAY: Mostly cloudy with flurries / Moderate to strong southwesterly ridgetop winds / Alpine high of -2
Avalanche Summary
On Monday, a skier triggered size 1.5 wind slab was reported on a south aspect at 1200 m.Over the weekend, skiers triggered a few size 1-1.5 avalanches on a 20 cm deep surface hoar layer at treeline elevations.A widespread natural avalanche cycle occurred last week. The 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. Following the natural activity, explosive control on Thursday produced more large and very large avalanches, but by Friday explosive testing produced mostly small avalanches.
Snowpack Summary
Surface snow consists of thin sun crusts, sugary faceted snow, and wind pressed snow on a range of aspects in exposed terrain. In sheltered areas at treeline and below, 20-30 cm of snow sits over a layer of surface hoar that has been reactive to skier traffic in isolated locations. A few deeper interfaces may have been reactive during last week's storm, but are becoming less likely to human trigger. These include layers of sun crust, facets, and isolated surface hoar buried 50-100 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 dryer parts of the region, such as in the far north.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.