Regions
Northwest Inland.
The weather pattern is fairly stable but watch for thin fresh wind slabs and lingering hard wind slabs in wind exposed terrain.
Confidence
Fair - Due to the number of field observations
Weather Forecast
Synopsis: There’s a chance of flurries tonight and Saturday morning as a weak frontal system brushes the Northwest. We should see a drying trend on Saturday and a mix of sun and cloud throughout the weekend. The freezing level remains at valley bottom and ridge winds are generally light from the SW. We could see increasing cloud on Monday as another Pacific system approaches. This could bring moderate precipitation, but it’s arrival looks more likely on Monday night or Tuesday.
Avalanche Summary
There are no new reports of natural avalanches. On Wednesday, a natural size 2 storm slab was reported in the south of the region and isolated natural wind slabs from steep terrain to size 1.5 were reported in the north of the region.
Snowpack Summary
A thin melt-freeze crust now covers the 40-80 cm of recent storm snow up to at least treeline. Strong and variable winds may have created soft or stiff wind slabs on a variety of aspects in exposed terrain. Below the storm snow may be a rain crust at lower elevations. In the mid-pack you may find a surface hoar layer, although it appears to be spotty in distribution. Near the bottom of the snowpack is a crust facet combo that was buried in mid-November.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.