Regions
Northwest Coastal.
Recent storm snow and southwesterly wind has formed reactive wind slabs. Natural avalanche activity will increase when temperatures rise and the sun comes out. Especially in areas that have received new storm snow.
Weather Forecast
The next pacific frontal system will reach the North Coast Friday night bringing cloud and precipitation through the weekend.FRIDAY: Mix of sun and cloud with alpine temperature high near 2 degrees and freezing levels 1300 m. Ridgetop wind gusty from the southwest.SATURDAY: Cloudy with snow amounts 10-15 cm. Alpine temperatures near -2 and freezing levels 1100 m. Ridgetop wind moderate to strong from the southwest.SUNDAY: Mostly cloudy with snow amounts 2-7 cm. Alpine temperatures near -3 and freezing levels near 1000 m.
Avalanche Summary
On Wednesday, reports indicated several natural slab releases and a cornice fall up to size 2.5. Skier triggered slab avalanches (remotely-from a far) were also reported up to size 1.5. We suspect these avalanches were primarily failing on the April 4th crust interface. Daytime warming produced loose wet avalanches on solar aspects up to size 2.
Snowpack Summary
Anywhere from 20-80 cm of recent storm snow sits above a weak layer buried April 4th. This layer consists of a 4 cm thick crust on all aspects and surface hoar/facets above the crust on northerly aspects. This layer has been reactive with the recent storm snow and fresh wind slabs will likely remain sensitive to human triggering through the weekend, especially on the higher elevation northerly aspects. Digging deeper, north facing alpine terrain also has a layer of facets down approximately 100 cm below the surface, but this layer has not been recently active and is likely trending towards dormancy.Below treeline the snowpack is isothermal and in some places below threshold throughout much of the forecast region.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.