Avalanche danger will increase throughout the day. The weather forecast remains uncertain, so consider the avalanche danger to be HIGH if there's more than 30 cm of new snow on Friday.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
FRIDAY: 20-30 cm of new snow, 40-60 km/h southwest winds, treeline temperature at -5.SATURDAY: 20-30 cm of new snow, 20-40 km/h southwest winds, treeline temperature at -3.SUNDAY: 5 cm of new snow, light northwest winds, treeline temperature at -5.
Avalanche Summary
Avalanche activity has declined throughout the week, but the storm snow remained reactive on Wednesday as ski cutting produced a size 1 avalanche on a steep unsupported feature. The likelihood and size of storm slab avalanches will increase throughout the day on Friday with heavy snowfall and strong winds in the forecast.
Snowpack Summary
A heavy pulse of new snow is expected for Friday and Saturday, although the weather forecast models don't agree on how much. By Friday afternoon there may be 20-30 cm of new snow on top of 30-50 cm of settling snow from last Monday. Northeast winds have likely formed thin wind slabs in exposed alpine terrain. A sun crust has been reported on the surface of steep southerly aspects, which may bond poorly with the new snow. A rain crust exists below Monday's storm slab, and recent reports suggest the storm snow may still be poorly bonded to the crust on shady north aspects. Below the crust, the snowpack is settled and strong. Total snowpack depths are 160-200 cm at treeline.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.