The storm may have tapered-off, but the snowpack will need time to adjust to the heavy load of the new snow, and water saturation at lower elevations. Conservative terrain selection remains critical.
Confidence
Fair - Due to the number of field observations
Weather Forecast
The pineapple express will persist for Sunday and Monday, but it will lose much of its "punch". A warm, dry ridge will then build for Tuesday. Sunday: Light precipitation / Strong southwest winds / Freezing level at 2000m Monday: 5-10cm of snow at higher elevations / Moderate to strong southwest winds / Freezing level at valley bottom with a chance of an inversion Monday: A mix of sun and cloud / Light northwest winds / Freezing level at valley bottom with a chance of an inversion
Avalanche Summary
Observations have been extremely limited in recent days. That said, several storm slab avalanches to size 2.5 were reported in the south of the region on Friday. I get the feeling this was just the tip of the iceberg. Triggering storm slabs will remain a concern at higher elevations for the next few days. At lower elevations where precipitation has fallen as rain, I would expect ongoing loose wet and wet slab avalanche activity.
Snowpack Summary
In the alpine, up to 50cm of moist, dense snow overlies a touchy crust/surface hoar layer which was formed in late January. These new snow accumulations have been pushed by strong southwest winds into much deeper deposits in upper elevation lee terrain. At lower elevations very heavy rain has saturated the snowpack. I'm sure cornices are large and fragile.The sustained rain should continue to break down the late January crust, increasing the possibility of avalanches stepping down to deeper weak layers. The mid-December crust/facet/surface hoar combo is found down 50 - 95 cm. Rain and/or heavy storm loading could spark renewed activity at this interface with the potential for very large avalanches.
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.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.