Regions
Northwest Coastal.
Watch for thin wind slabs in the alpine that could be problematic, especially in complex terrain.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Thursday
Weather Forecast
Wednesday: Increasing cloud cover. Light SW winds at treeline, Moderate W/SW winds at ridgetop. Freezing level rising to 800m, lowering to 500m overnight. No significant precipitation. Wednesday Night: 2 to 10cm of snow. Thursday: 5 to 15cm of snow. Strong SW winds at treeline, Strong to Extreme SW winds at ridgetop. Freezing level rising to 1200m, lowering to 800m Thursday night. Friday: 1 to 5cm of snow. Light SW winds at treeline, Strong W/SW winds at ridgetop. Freezing level holding at 800m.
Avalanche Summary
A size 3 avalanche was observed from a steep un-skiable solar aspect over the weekend. Several small wind slabs were observed on Monday. Last week, several full-depth avalanches up to size 3 were observed on all but north aspects.
Snowpack Summary
Northerly outflow winds have likely created isolated stiff thin wind slabs in lee alpine terrain. A variety of other surfaces can be found including a skiff of recent snow, a sun crust, an old rain crust, surface hoar, and/or surface facets. At the base of the snowpack, weak facets may be found. Keep an eye out for cornices that could become weak with daytime warming.
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.