Touchy conditions exist in the North of the region with the potential for large and destructive avalanches becoming more likely as temperatures rise.
Confidence
Fair - Freezing levels are uncertain on Wednesday
Weather Forecast
Wednesday: Very light rain. Winds out of the SW begin to pick up as warm air floods into the region. Look for moderate SW winds at treeline, strong to extreme W winds at ridgetop. Freezing level should climb to 2500m by late afternoon.Thursday: No significant precipitation expected. Moderate SW winds at treeline, strong W/SW winds at ridgetop. Freezing level starting the day at 2500m, climbing to 2800m by Thursday night.Friday: No significant precipitation. Freezing level starting around 2800m, lowering slightly to 2200m by the end of the day. Winds moderate SW at treeline, strong to extreme SW at ridgetop.
Avalanche Summary
Over the past week, there have been a number of avalanches to size 2.5 occurring on the March 11 persistent weak layer. Some avalanches have occurred naturally, or remotely from distances of up to 100m. Hot spots for avalanche activity seem to include the Duffey Lake area, the Birkenhead drainage, the Hurley and the South Chilcotins. No new activity to report from Monday.
Snowpack Summary
A few centimeters of new snow fell Monday night. This new snow rests on top of wind slabs that formed over the last few days in response to recent wind, snowfall and warm temperatures. At lower elevations, rain has saturated the snowpack. Cornices may also be fragile. A touchy crust/facet persistent weak layer, buried up to 60 cm down, has been reactive producing easy test results at upper treeline and alpine elevations, especially in the north of the region (see avalanche summary). Avalanche problems associated with this layer may linger for a while with the potential for surprisingly large and destructive avalanches. Below this, the snowpack is reported to be generally well-settled and strong.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.