Be extra cautious around south slopes: they're weak, wind-loaded, and getting hit by the sun.
Confidence
High - Due to the number and quality of field observations
Weather Forecast
WEDNESDAY: A mix of sun and cloud, light north winds, alpine temperatures around -20.THURSDAY: Cloudy with isolated flurries, light west winds, alpine temperatures around -16.FRIDAY: Cloudy with isolated flurries, light southwest winds, alpine temperatures around -14.
Avalanche Summary
On Monday, numerous natural wind slabs in the size 1-2 range were reported on south and southwest aspects. A larger size 3 avalanche was reported to have been triggered by a wind slab stepping down to a deeper weak layer on a steep south-facing alpine slope in the Selkirks.Wind slabs may remain reactive to human triggers in specific areas, such as the immediately lee of ridges and sun-exposed slopes.
Snowpack Summary
Strong winds over the weekend had an extensive effect in exposed terrain. Expect scouring and wind slabs in unusual places, as the winds shifted from west to northeast. Sunny weather is likely making the surface snow touchy on south-facing slopes. The mid-December facet/surface hoar layer can be found buried 80-120 cm deep, and has been showing signs of gaining strength recently with little to no recent avalanche activity in the region. The layer may still be reactive in isolated areas such as steep south-facing slopes and thin snowpack areas. The lower snowpack is well bonded and features a thick rain crust near the ground.
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.