Regions
South Coast Inland.
Wind slabs are slowly gaining strength but you can expect those on south aspects to become touchy with any solar radiation.
Confidence
Moderate - Wind effect is extremely variable
Weather Forecast
We're in a warming trend with little if any precipitation expected this weekend. Things start to change on Monday, stay tuned. SATURDAY: Cloudy with sunny breaks and isolated flurries. Winds moderate (20-35 Km/hr) from the southwest. Alpine temperatures around -8 Celcius. SUNDAY: Increasing clouds in the afternoon. Winds light-moderate southwesterly. Freezing level rising to 600m and alpine temperatures around -6 Celcius. MONDAY: Snow beginning near noon. Winds modearate to strong from the southwest. Alpine high temperatures to -2 Celcius.
Avalanche Summary
Several Size 2 natural avalanches were seen on north aspects in the Hurley zone on Tuesday and also farther northwest (Size 2.5) on Thursday.A MIN report from Sunday details a skier triggered avalanche in the south of our region. The avalanche was triggered near treeline on a southwest-facing slope where there appeared to be evidence of recent wind loading. Other reports from Tuesday include several Size 1.5-2 avalanches running naturally in steep west and northwest-facing terrain in the north of the region.
Snowpack Summary
The main story is widespread variability due to all the shifting wind patterns, distributing and redistributing snow over the past few weeks. 25-30cm of low density snow fell over Sunday and Monday in the southern (Coquihalla) area, while northern sections received 7-15cms of new snow. During the storm, moderate southwesterly winds distributed the new snow onto north and east aspects, forming reactive soft slabs. After the storm, winds shifted to classic outflow (northerly) patterns on Tuesday with moderate winds at ridge top. This pattern resulted in 'reverse loading' of wind slabs onto southerly slopes as far down as 1850m in the north (Duffey Lake zone) and 1700m in the south (Coquihalla area). These new, old and variable wind slabs are the primary weaknesses of concern in the snowpack. The older wind slabs from a week ago (on south to west aspects) remain a concern in our current snowpack with recent cold temperatures having slowed their healing into the snowpack.
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.