Avalanche Forecast
Regions: Olympics.
You are likely to trigger a storm slab where recent moderate winds have stiffened snow surfaces or where settlement and sunshine consolidate the thick storm snow layer into a slab. The slab sits on heavily faceted old snow which will increase slab propagation to produce large avalanches.
Discussion
Snow and Avalanche Discussion
Avalanche danger at Hurricane Ridge has rapidly increased sharply over the past several days. That began to change on Friday as 7" of low-density snow fell quickly during the day with little wind. NPS rangers reported natural and skier triggered loose dry avalanches releasing on steep northerly aspects as the snow piled up. The storm continued into Saturday with moderate winds developing Friday night and delivering up to 2.5’ of storm total accumulation near the Park entrance along with frequent natural Loose Dry avalanches spitting out of steep gullies around 3000 ft. Less total snow is expected at Hurricane Ridge proper.
NWAC professionals in the Hurricane Ridge area on Thursday found about 5-7 inches of low-density snow above the most recent crust surfaces. The snow surface was universally weak with more facets (weak snow) on north through east aspects near and above treeline in the terrain they traveled. Avalanches are more likely to fail on these weaker, older snow interfaces.
Forecast schedule
For the 2018-19 winter season, avalanche hazard ratings will be issued for the Olympics Friday through Sunday and during holidays. We will resume issuing ratings when access is once again available following the recent government shutdown.
General snowpack and weather summaries will be available on days that the Hurricane Ridge road is closed.
Snowpack Discussion
Regional Synopsis coming soon.Â
Avalanche Problems
Storm Slabs
You are likely to trigger a storm slab as the recent storm slab settles into a slab. This may have already occurred in areas where winds have moved significant snow. During the day, settlement will occur with time and will be accelerated where the sun affects snow surfaces. These slabs are expected to be 1-2.5’ deep (or greater in wind-affected areas) and sit on 4-6” of faceted snow above a supportable crust. Sunday is not a day to let your guard down because the avalanche danger is likely to increase as the day wears on. Use test slopes to help determine whether a slab problem exists in your area. If it does, choose simple terrain with slopes less than 35 degrees. If no slab forms in your area, Loose Dry avalanches will run far and fast and will be large enough to bury you on any steep terrain or push you into terrain with higher consequences.
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-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.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 1