The bottom line: Upwards of 1 ft of new and recent snow combined with sustained moderate winds gusting strong Thursday and Thursday night will create large and reactive slabs, particularly near and above treeline. The reactive snow will need time to settle. In the Hurricane Ridge where less new snow has fallen, navigate around shallow wind slabs and drifts on leeward features.
Snow and Avalanche Discussion
A rain/snow mix with 0.10” of snow water equivalent fell at Hurricane Ridge on Thursday and was blown around at higher elevations by increasing moderate winds, gusting strong. The eastern Olympics received up to 0.75” of snow water equivalent.
This new snow above 5,000 - 5,500 ft sits on a variety of suspected surfaces including crusts, facets, and surface formed during the preceding week of fair weather and clear skies. At lower elevations, rainfall should have eliminated some of the weak snow surfaces.
A cooling trend with light snow showers is anticipated on Thursday. Avalanche danger is likely to peak early in the day, but with another storm system beginning to impact the region late in the day, avalanche danger will start rising once again.
At higher elevations, several storm layers exist and may be sitting on a crust or weak snow. Test these layers using quick tests along your skin track. If you find reactive snow layers deeper than 4-6” or poor bonding between snow interfaces, stick to lower angle slopes well away from potentially wind-loaded slopes where reactive slabs are most likely.
Shallow snowpacks have receded significantly and a recent report suggests you may not find much if any, snow below 5,000 ft in many of the drier parts of the Olympics.
Right now we are forecasting without specific snowpack and avalanche observations from the Hurricane Ridge area due to the government shutdown. If you travel to the Olympic Mountains, please help your local forecast by submitting an observation. We haven’t received updated snowpack information for nearly one month.
Regional Synopsis
January 16, 2019
Since Friday January 11, we’ve enjoyed a spell of generally nice weather in the mountains. This allowed for some great views, enjoyable outings, and lots of snow observations. A more active weather pattern beginning Thursday January 17th will bring this nice weather to a close.
During this time period, the snow surfaces around the area have changed dramatically. This forms the foundation for a few current trends we are seeing in the mountains.
New Snow Problems
Reports from around the area indicate a wide variety of snow surface conditions prior to new snow on January 17th. We’ve heard about breakable crust, very icy surfaces, sugar facets, surface hoar, and rime. What snow surface you encounter can depend on aspect, elevations, and general location.
As a series of winter storms impact the area, how will the new snow bond to the old snow surface. This can be tricky to predict. As the snow starts to pile up make lots of shallow snow observations. Shovel tilt test, hand shears, and small slope test can all help you track how the new snow is bonding to the old snow at different aspects and elevations. Stop and take a look at where the snow is failing. Do you see large grains of snow? Do they look like feathers? Do the act like sugar? How far below the current snow surface are they?
Old Snow Problems
There are still lingering persistent weak layers in the eastern zones of the cascades. You are most likely to find weak older snow in areas further east from the Cascade crest where snowpacks are shallower, more variable, and generally weaker. In some locations weak snow near the ground can still be found. These basal facets have hung around all season. The only way to gain information about these old persistent weak layers is to get out your shovel and dig. Because of the size of our forecast zones and the variability in the snowpack, it's important to make snow observations as you travel. We’ll keep watching these old layers, but let us know what you see while you are in the mountains.
