Avalanche Forecast

Light snow showers should resume on Sunday with light to moderate west winds. A slight warming trend should be seen by Sunday afternoon.

Small wind slab mainly on NE slopes may linger on Sunday. But watch for firmer wind transported snow on all aspects due to recent varied winds especially above treeline.

Light snow showers on Sunday may further bury intact a variety of weak surface snow types formed this week under fair cold weather. This is likely to become a weak layer starting Monday.

The December 8th layer should be strong enough to not be a problem in the Olympics. But head for lower angle slopes and ratchet back your plans if you experience collapsing or whumpfing or have evidence of this layer such as from snowpits.

Even though the lower part of the below treeline band is filling in, watch for early season travel hazards such as barely covered rocks and open creeks.

Note that the first in a series of storms is expected to begin to move across the Northwest Sunday night. This will bring a significantly increasing avalanche danger by Monday.

Weather and Snowpack

The last storm cycle to affect the Olympics and most of the Washington Cascades was from Thursday, December 8th to Monday morning, December 12th. About 2.6 inches of water equivalent and about 3 feet of snow fell at Hurricane Ridge ending Monday morning Dec. 12th. 

Fair and cold weather this week has been interspersed with periods of moderate NE-E winds Wednesday and Friday. These winds were strong enough to build fresh wind slabs on more atypical SW-NW facing terrain, mainly near and above tree line.

There has been about 12 inches of snowpack settlement since the storm cycle ended, allowing underlying or storm snow related weak layers to stabilize. 

Several clear nights with light winds this week have caused weak surface snow development. On wind and sun sheltered terrain, extensive near surface faceted snow or surface hoar has formed this week and this may be an important weak layer if buried intact by light snowfall Saturday or Sunday.

A thin sun crust is likely to have formed on steeper southerly facing slopes, which also may be a future interface for avalanches when loaded with sufficient wind transported or future storm snow.

Recent Observations

A regional avalanche cycle was seen December 8th-11th in the Cascades with some avalanches releasing on the December 8th persistent weak layer in the Washington Cascades. 

NWAC pro-observer Matt Schonwald was at Hurricane on Friday and found a mostly right side up snowpack. The December 8th layer was found at a depth of 30 cm but gave moderate to hard compression tests and did not show signs of propagation. Isolated small wind slab was found on NE slopes above 5000 feet. He noted widespread large surface hoar and near surface facet snow that will be a weak layer if buried by future snowfall.

Surface hoar at Hurricane Ridge on December 16th. Photo by Matt Schonwald.