Avalanche Forecast

Moderate -

Wednesday: Cloudy with scattered flurries bringing about 5 cm of new snow, continuing overnight. Light south winds. Freezing level to about 700 metres with alpine high temperatures of -7.Thursday: Cloudy with continuing flurries and about 5 cm of new snow over the day. Increasing overnight. Light southwest winds, increasing overnight. Freezing level remaining near 700 metres with alpine high temperatures reaching -5.Friday: Cloudy with continuing flurries and about 5 cm of new snow. Moderate southwest winds. Freezing level rising to 1500 metres with alpine high temperatures around -2.

Reports from Monday include observations of explosives control in the Whistler area producing numerous storm slab releases generally from Size 1.5 to 2.5 but with several Size 3.5 results and even one Size 4.Saturday and Sunday's reports showed ski cutting as well as explosives control in the Whistler area producing numerous storm slab results from Size 1-2, as well as several Size 1.5 cornice releases. A report from Friday detailed two explosive triggered Size 3.5 persistent slab avalanches. These avalanches started in the storm snow and then stepped down to the early January and even the mid-December crusts which resulted in very large avalanches running full path. They occurred on northwesterly aspects below rocky ridgetops between 1950-2200 m.

Monday's continuing storm brought another 30-40 cm of new snow to the surface above about 1600 metres with depths that increase with elevation. At higher elevations, extreme southerly winds have been scouring the new snow from windward aspects and forming deep deposits and cornices in leeward terrain. Including the new snow, storm snow totals since mid-January have reached about 170 cm. Where they haven't been blown away by the wind, these accumulations sit on a crust from mid-January that shows good signs of bonding to the overlying snow. Other deeper layers in the snowpack include a crust that was buried in early January (now 230-280 cm below the surface) and another crust which was buried in mid-December. Although explosive control work triggered storm slab avalanches that "stepped down" to both of these crusts last week, they are expected to have formed an improved bond with the overlying snow in most areas. With that said, a heavy trigger like a cornice release may still carry the risk of stepping down to deeper layers on isolated features where winds have created more variable snowpack depths and brought these layers closer to the surface.