Avalanche Forecast

A frontal system on Thursday should bring light to moderate snowfall in the north Cascades and moderate to occasionally heavy snowfall in the south and central Cascades during the daylight hours. The south Washington Cascades, including locations like Crystal and Paradise should see a gradual warming trend Thursday afternoon while the north Cascades should see little change.  

Avalanche problems will revolve around storm and wind slab. New and recent snow will be deposited on lee W through E aspects, although initially be wary of lingering wind slab on E-SE slopes from transport earlier in the week. Most avalanches should stay within the new storm snow, but a few may step down to older storm layers or crusts in isolated locations.    

As snowfall and winds increase, avoid steeper slopes and watch for increasingly sensitive storm layers. Generally avoid wind loaded terrain in the near and above treeline zone with new snow being transported to a variety of aspects.

The storm related avalanche danger will increase further Thursday night into Friday morning.  

Terrain anchors are still causing significant anchoring at the lowest elevations. Use caution near creeks which are still open in some areas.

An atmospheric river around Dec 9th pushed heavy rain up to at least 6000 feet in the north Cascades and above 7000 feet in the south. Below these elevations water percolated down below the early December crust (date at which when the crust was buried) and is expected to have eliminated or subdued persistent weak layers formed mainly in late November in the Stevens and Snoqualmie area. An active and cool weather pattern over the last week has produced about 2 to 3 plus feet of new snowfall that now sits over the 12/9 crust. The below treeline zone snowdepth is filling in nicely but still contains many barely hidden hazards like rocks, streams or snags. The skiing in non-wind affected areas with enough snow cover has been good! 

Last weekend, most avalanches released within storm layers, but a few released down to the recent rain crust. Storm instabilities have had time to heal and no new avalanches were reported Tuesday or Wednesday. The NWAC staff along with other Stevens Pass professionals had field training Monday and Tuesday in the Stevens Pass area and found a reactive graupel or stellar layer at 35-40 cm down but tests did not indicate propagation was likely. Moderate west-northwest winds in the above treeline zone along with light amounts of new snow received Tuesday night through Wednesday morning have likely redistributed recent and new snow onto lee easterly slopes in the near and above treeline zones.