If more than 20 cm of new snow falls on Tuesday, the Avalanche Danger may be HIGH in the alpine.
Summary
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Tuesday
Weather Forecast
Between 10-15cm of new snow is expected for the Whistler are on Tuesday with up to 25cm of snow possible in the south and western portions of the region. Winds will be strong and southwesterly with freezing levels at about 1700m. On Wednesday 20cm of wet snow is expected with strong southwest winds and freezing levels hovering at about 2200m.
Avalanche Summary
Explosives control on Sunday produced a few cornice collapses to size 2. An explosive charge also triggered a size 2 persistent slab avalanche on an adjacent alpine slope where buried surface hoar was lingering. There were also a few human involvements on Sunday. A snowboarder got too close to a recently formed cornice and triggered a size 2 cornice fall. The individual was not injured in the event. Of note, a size 1.5 persistent slab avalanche was also reported on Disease Ridge in the Spearhead Range. An individual was partially buried in the event, but was assisted quickly by their party. Looking forward, a warm, wet weather system is expected to spark a new round of wind slab activity in high elevation lee terrain, but warm temperatures and loading will also increase the likelihood of waking up any lingering persistent weaknesses that were not triggered by last week's storm.
Snowpack Summary
The "Pineapple Express Light" dumped 80-160 mm of precipitation on the South Coast this week. Most of this fell as snow above 1800-2000 m (over 1 m) with mixed rain and snow or just heavy rain below 1800 m. Heavy snow and strong winds have formed deep and dense wind slabs in exposed lee terrain and caused substantial cornice growth. Expect to find a rain crust at or near the surface (below 10-20 cm of fresh snow) at lower elevations. In many areas, the early and mid-January surface hoar layers may have been wiped-out by the storm and subsequent avalanche cycle; however, recent Mountain Information Network observations from the Spearhead range show this layer is still producing "sudden" test results. These layers would be down between 80 and 150 cm deep, and still have the capacity to surprise with nasty consequences. The mid and lower snowpack is generally strong, with the exception of shallower snowpack areas that may be more faceted.
jlammers,
Avalanche Canada
