Avoid all avalanche terrain on Friday. Large destructive avalanches will be widespread.
The incoming storm will add tremendous stress to buried weak layers. Very large avalanches will likely release on these layers, run far distances, and potentially even damage or destroy forests.
Large avalanches are almost certain as 40-100 cm of new snow, strong wind, and warming temperatures will cause a natural avalanche cycle.
THURSDAY NIGHT: Snowfall intensifying overnight with 20-50 cm of snow by the morning, freezing level rises overnight with rain up to 1200 m, strong wind from the southwest, alpine temperatures increase to -2 C.
FRIDAY: Heavy snowfall continues in the morning with another 20-50 cm by noon (and 24 hour totals of 40-100 cm), snowfall intensity eases off midday and then a second intense pulse starts in the late afternoon, freezing level will remain steady throughout the day with rain up to 1500-1700 m, strong wind from the southwest, alpine high temperatures around -1 C.
SATURDAY: A second intense storm starts Friday evening bringing another 30-50 cm of snow above 700 m by Saturday afternoon, moderate wind from the southwest, freezing level drops to 700 m with alpine high temperatures around -4 C.
SUNDAY: Yet another storm brings 15-30 cm of snow, strong wind from the south, alpine high temperatures around -4 C.
Very large avalanches are almost certain on Friday as intense precipitation will form large storm slabs and add tremendous stress to an already weak snowpack. Avalanches have the potential to run far distances and destroy mature timber. The greatest danger will be during the peak intensity of the storm on Friday morning, but large natural avalanches are likely throughout the day (and the rest of the weekend). A relatively weaker storm on New Years Day resulted in large (size 2-2.5) avalanches on both storm interfaces and deeper weak layers.
A barrage of intense storms will continue to cause a widespread storm slab problem. 40-100 cm of snow is expected between Thursday night and midday Friday (40 cm around Whistler and greater accumulations further west and south). The snow line will be around 1200 m, so heavy rain is expected at lower elevations. The previous storm deposited about 40 cm of snow above a layer of surface hoar on New Year's Day, which resulted in reactive storm slabs the past few days. There are multiple weak layers buried deeper in the snowpack, including a variable layer of surface hoar and crust from mid-December (down 70-90 cm) as well as a deeper layer of sugary facets and crust buried in late-November (down 120-200 cm). Both of these persistent weak layers produced many large and destructive avalanches over the past few weeks. This fundamentally unstable snowpack structure remains a serious concern as new snow and wind add a critical load and increase the likelihood of triggering large and destructive avalanches.
