Regions
Northwest Inland.
Lack of recent avalanche activity indicates we haven't seen the loads necessary to trigger buried weak layers. Conservative route selection is still essential to staying safe.
Confidence
Fair - Due to the number and quality of field observations
Weather Forecast
A fast moving cold front will pass through the area Thursday evening bringing strong south winds and 5 to 10 cm of new snow at the upper elevations. Freezing levels should remain around 500m, but may dip to valley bottom. Friday will have a break in the weather before the next pacific system arrives on Saturday.
Avalanche Summary
No reports of avalanche activity in the region yesterday, but further west there have been reports of large natural avalanches on s facing slopes at upper elevations. We just having seen the quantity of snow in the NW Inland,..yet.
Snowpack Summary
Strong South winds will build wind-slabs on lee aspects in exposed terrain, generally depositing snow on N and NE aspects. Below the recent storm snow is a rain crust at lower elevations and a temperature crust that formed on the surface above treeline from the last temperature inversion. In the mid-pack a surface hoar layer has been reported, as well as a mid-December crust, but we haven't seen any activity on it recently. Most likely because it hasn't yet received a significant load on it. Near the base of the snowpack is a November crust-facet combination that could remain problematic for some time.
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.