Regions
Northwest Coastal.
Confidence
Fair - Intensity of incoming weather systems is uncertain
Weather Forecast
Unsettled conditions and light precipitation are expected on Tuesday before the next major system reaches the North Coast on Wednesday. Tuesday: Mostly cloudy, light precipitation 4-8cm, freezing level around 400m, moderate SW windsWednesday: Snowfall 15-25cm, freezing levels around 500m, moderate to strong SW windsThursday: A mix of sun and cloud, light flurries possible in the morning, light W winds
Avalanche Summary
No recent natural avalanches have been reported. On Sunday, numerous explosive triggered storm avalanches were reported up to size 2.5.
Snowpack Summary
Southern Sections: The latest weather system dropped another 30 cm of snow, bringing the total snowfall over the past week to around 150 cm. The recent storm snow is likely "upside down" feeling, with heavier snow on top due to warming at the tail end of the system. Winds were also very strong from the SW most likely creating fresh wind slabs in exposed lee terrain at all elevations. Freezing levels climbed to near 1500 m resulting in moist snow or rain below treeline. Much of the low elevation snowpack has been washed away by recent rain.Northern Sections: Weaknesses may still exist within the recent storm snow which is now totalling over 80cm in the last week. Fresh dense wind slabs are likely in exposed lee terrain and cross-loaded features at all elevations. A recently buried surface hoar layer is now down around 80 cm and is likely primed for rider triggering. A facet/crust layer exists near the base of the snowpack, primarily on higher NW through E facing slopes. Triggering this layer may be unlikely, but if triggered the resulting avalanche would be very large and dangerous.
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.