Regions
Northwest Coastal.
Confidence
Fair - Forecast snowfall amounts are uncertain on Tuesday
Weather Forecast
Tuesday: We could wake up to 10-15cm of new snow. Through the day we may see up to another 10cm. Ridgetop winds will be strong from the south west. Treeline temperatures near -5, with freezing levels at valley bottom. Wednesday/ Thursday: A ridge will rebuild over the area bringing a mix of sun and cloud, with more snow expected later in the week.
Avalanche Summary
One natural size 2.5 was reported on a steep NE aspect at 1200m failing to ground. No additional information on this avalanche. Expect avalanche activity with current conditions and forecast weather.
Snowpack Summary
New snow and wind over the next 32 hrs will add an additional load to the current snowpack. The upper snowpack consists of a variety of snow surfaces. The region did receive up to 20cm of snow early in weekend which produced sluffing in steeper terrain features. It also buried a variety of snow surfaces including surface hoar, a melt freeze crust, and facets (sugary snow). Most operations in the region have reported large surface hoar (feathery type snow crystal) that is sitting on a thick melt-freeze crust. This crust is up to 20cm in thickness and extends up to alpine elevations in the south, and around 1000m in the north. A strong temperature gradient in the top 30cm was reported to be faceting snow below the surface crust. The mid and lower snowpack are generally well settled and strong. My main concerns are new wind slab formation on lee slopes. With the strong ridge top winds you can expect some wind slabs lower on slopes, or found in unsuspecting places. Storm slabs may also be an issue if they reach threshold over the weak buried snow surfaces. They can run fast, and far.
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.
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.