The rain (yes rain) has stopped. Natural avalanches are less likely today but human triggering is likely. More rain is expected overnight, and danger will rise again Friday. By the weekend temperatures will drop, and the wet snowpack will tighten up.
Weather Forecast
There should be a lull in the storm today with isolated wet flurries, freezing levels to 2000m and south winds gusting to 40km/hr. Overnight, showers will bring up to 7mm of rain to 2000m. The weather pattern will be the same on Friday with showers up to 2000m. On Sat, freezing levels will finally drop to 1300m with a low of -3 and a trace of snow.
Snowpack Summary
More rain than snow fell yesterday at 1900m; 8mm of rain fell at Rogers Pass. A ~25cm storm slab, thicker in windloaded areas, will bond poorly where it overlies surface hoar or sun crust. Below 1600m it will bond poorly to a rain crust. The Nov persistent weak layers, down ~105 and ~140cm, have the potential to create large avalanches.
Avalanche Summary
Natural avalanche activity continued yesterday, with numerous size 2-2.5 avalanches occurring from all aspects and running onto avalanche fans. Avalanche debris is wet in character. The Laurie avalanche path, on the park's west boundary produced another size 3 avalanche yesterday.
Confidence
Timing, track, or intensity of incoming weather system is uncertain
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.
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.