Regions
Northwest Inland.
The danger has come down slightly, but the snowpack needs more time to adjust before we start to size up more challenging objectives.
Confidence
Fair - Due to the number of field observations
Weather Forecast
Clear and dry weather is forecast for the period. No precipitation is expected. Winds should decrease Saturday afternoon, but they remain strong SW at upper elevations Sunday. Monday and Tuesday look the same, but all bets are off for Wednesday. The current models show the freezing level rising to 2000m. Too early to say how that will play out.
Avalanche Summary
I suspect large natural avalanches were running Friday, but we do not have any observations from treeline/alpine elevations where the action is at.
Snowpack Summary
The storm has produced approximately 30 to 70 cm of new snow accompanied by strong to extreme winds out of the E through SE. There are a number of weak layers in our snowpack, this storm should be a good test for all of them. In places the new storm snow sits on the early February surface hoar, little is known about the distribution of this interface. The late January crust is probably down 60 to 100cm in the south, it's likely shallower in the north. The mid-January rain crust(with some spatially spotty surface hoar on top) is down over a meter. It might still be a problem in thin snowpack areas. The crust/facet combination from November can be found near the ground. It's not an easy snowpack to work with, we'd greatly appreciate your observations via the Mountain Information Network.
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.
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.