Winter-like conditions have returned to the region, use caution in wind-loaded terrain and on big features
Confidence
Fair - Due to the number and quality of field observations
Weather Forecast
Although the most recent Pacific frontal system has passed through the area, unsettled weather and convective flurries continue to bring moderate amounts of precipitation to the area.MONDAY: Cloudy with flurries 5 to 10cm of snow expected for the region. Freezing level will rise to 1600m with moderate to strong winds from the South West.TUESDAY: A brief break in the weather pattern. Cloudy with sunny periods, freezing level around 1200m, winds light to moderate from the South West. WEDNESDAY: Cloudy with flurries, freezing levels rise close to 1700m, with moderate winds from the South West.
Avalanche Summary
No reports of avalanche activity from yesterday. This is most likely as a result of few field observations. We expect wind slab activity with new loading and strong winds. Solar aspects will become active again when the sun come out, and cornices will again be on our radar.
Snowpack Summary
30 to 50cm of recent storm snow now rests on a variety of crusts and old surfaces including surface hoar and facets that formed in sheltered locations during the recent clear weather. Moderate to strong south west winds are redistributing the storm snow into wind slabs on the lee sides of ridge tops. A facet/crust layer that was buried in mid-March is now approximately 50-100 cm down. This remains a concern in the region because of it's potential for very large avalanches. Cornices are now large and mature and may collapse with increased loading, possibly triggering the deeply buried weak layer.
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.
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.