Regions
Northwest Coastal.
Watch for fresh sensitive wind slabs in exposed terrain at and above treeline.
Weather Forecast
Synopsis: Arctic air to dominate for a few days, then warming from the north. Outflow winds should reach their peak Monday night. By Tuesday afternoon warmer Pacific air associated with the offshore upper ridge should move inland opening the door to a potential inversion or an above freezing layer between 1000 & 2500m.Tuesday: Freezing Level: Valley Bottom; Precipitation: Nil; Wind: Treeline: Light, W/NW | Ridgetop: Strong, W/NW.Wednesday: Freezing Level: Valley Bottom, potential AFL 1000 2500m; Precipitation: Nil; Wind: Treeline: Light, NW | Ridgetop: Strong, NW.Thursday: Freezing Level: 800m, potential AFL 1000 1500m; Precipitation: 3-10mm | 3-10cm; Wind: Treeline: Moderate W/SW | Ridgetop: Extreme, W
Avalanche Summary
Over the last few days we've had reports of naturally and skier-triggered size 1-2 slabs, mostly wind slabs on lee slopes at treeline and above. Explosive control with a cornice drop on Saturday produced a size 2.5 storm slab on a north-facing slope at 1400 m.
Snowpack Summary
Up to 30 cm of new snow from Friday night is being formed into new wind slabs on lee aspects as the winds shift into an outflow pattern. The mid and lower snowpack are generally well-settled. Several old crust layers exist but these appear to be well bonded.
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.