Avalanche Forecast

Expect rapidly lowing freezing levels and an abrupt pattern change on Friday morning as a short round of rain and snow adds a shallow blanket of new snow on top of the highly variable existing snowpack. We'll be watching to see whether faceted crystals are preserved and buried as this round of precipitation moves through.

Snow accumulation and wind will combine to produce snow transport that should be marginally sufficient for wind slab formation. With some uncertainty in the strength of the winds and new snow amounts and the surfaces buried underneath, watch for signs of denser snow on top of settled powder or faceted crystals on non-solar aspects or increasing snow density on top of firmer melt-freeze layers on east through south aspects. With a lot of variety in the surface snow conditions right now and additional snow arriving through the weekend, Friday is an excellent day to submit an observation to NWAC to help us better define the extent of developing avalanche problems.

Early season terrain hazards have become an increasing hazard in recent days with poorly covered rocks, vegetation and creeks, particularly on south-facing terrain, at lower elevations, and on exposed ridges where wind events have stripped much of the seasons snowcover.

Strong high pressure has prevailed since December 3rd with Thursday's high clouds portending Friday's pattern change. Sunshine and very mild temperatures have been the story with cooler temperatures and areas of low clouds at lower elevations. This weather has allowed for overall strengthening and consolidation of an already strong snowpack. Total snow consolidation at Hurricane Ridge is about 6" since December 3rd. The upper snowpack consists of about 1 to 1.5 feet of settled old storm snow over the strong Thanksgiving rain crust. 

No human-triggered avalanches have been reported in over a week. Some natural small loose wet slides have occurred on mainly steep sun exposed slopes over the last week, but have become much less frequent in recent days. Active wind loading has not been observed since late last week. 

Surface conditions are highly variable. On solar aspects, surface melt-freeze crusts reform every night. On shaded aspects, there may be a mix of frozen surfaces in the trees with patches of good skiing and riding in sheltered areas. Many aspects in higher terrain now feature wind stiffened snow. Near surface faceting and surface hoar growth have been reported on colder, non-solar aspects in similar experiencing similar temperature regimes in recent days on the west slopes of the Cascades and should also be possible in specific locations around Hurricane Ridge. The formation of these layers should be limited due to the very warm temperatures experienced in the Olympics. However, any persistent grain types will become important when snowfall returns and watched as potential future weak layers. 

Observations

NWAC Professional Observer Matt Schonwald was in the Hurricane Ridge area on Sunday, December 10th. The average height of snow in most areas was consistently around 4 feet deep. About 16 inches of settled and creamy snow was found well bonded to the Thanksgiving rain crust with strong snow to the ground.

Terrain up to 45 degrees was skied with no signs of instability. Only a few isolated loose wet slides were evident from the past day or so and were small and isolated to steep slopes above terrain absorbing greater radiation, such as cliff and rock band features.

There was some small surface hoar growth on sheltered E-SE facing slopes, not receiving direct low angled sun. No surface hoar or near surface faceting was seen on other slopes, including north facing.