Regions
Northwest Coastal.
The positioning of the band of heaviest snowfall is uncertain. Some areas may see 20 cm on Thursday, some may get less than 10 cm. Where snow accumulates, treat it with added caution and make conservative choices.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
WEDNESDAY NIGHT: Cloudy with snowfall, accumulation 10 cm, freezing level 800 m.THURSDAY: Cloudy with snowfall, accumulation 15 cm, light to moderate southwest winds, alpine temperature -1 C, freezing level 800.FRIDAY: Cloudy with snowfall, accumulation 20 cm, light to moderate southwest winds, alpine temperature -5 C, freezing level 300 m.SATURDAY: Mostly cloudy with light snowfall, accumulation 5 cm, light southwest winds, alpine temperature -14 C, freezing level below valley bottom.
Avalanche Summary
On Wednesday, a few small pockets were reactive to skier traffic, with slabs up to 15 cm deep. Otherwise, no new avalanches were observed in the region.
Snowpack Summary
New snow will fall with an incoming storm. It will fall on a wind-affected surface, such as scoured snow on windward slopes and thicker snow deposits in lee terrain features. The snow will fall on a melt-freeze crust below treeline.Around 40 cm of snow may overly a weak layer of feathery surface hoar crystals in sheltered and shaded areas and a melt-freeze crust on southerly aspects. The layer is likely most prominent around Bear Pass and in the north of the region, but may still exist above around 1600 m in the south of the region.Within the middle and lower half of the snowpack, a few weak layers may still exist in the north of the region. These include another layer of surface hoar around 50 to 100 cm deep and a weak layer of sugary faceted snow around 200 cm deep.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.