Avalanche Forecast
Regions: Olympics.
More than a foot of snow fell in Hurricane Ridge area and will form a slab. Give the snow another day to settle and bond to the underlying snow before venturing into steep or complex terrain.
Discussion
Snow and Avalanche Discussion
As the sun comes out on Monday, expect small loose snow on steep south-facing slopes as rocks and branches start shedding their snow. These avalanches will be dangerous in complex terrain features including terrain exposed to rocks, trees, steep gulleys, or cliff bands.
The most recent observation is from a variable and shallow 2-3’ snowpack at 5400’ in the eastern Olympics, on December 22nd, prior to the recent storm. Alternating melt-freeze layers and rounding grains were observed.
These observations are similar to the snow structure last reported from Hurricane Ridge (8 days old). Expect extreme variation in snow depths in the Hurricane Ridge area due to stormy conditions throughout the last two weeks. The below treeline snowpack is likely still marginally thin to support avalanches below 4500'.
Forecast schedule
For the 2018-19 winter season, avalanche hazard ratings will be issued for the Olympics Friday through Sunday and during holidays.
On days that the Hurricane Ridge road is closed, No Rating will be applied. We will continue to provide general snowpack and weather summaries for the Hurricane Ridge area even when No Rating is issued.
Avalanche Problems
Storm Slabs
Recent storm snow is the primary concern on Monday. A 1-1.5 ft slab is expected on Monday, deposited at temperatures just under 30 degrees with initially moderate to strong winds. The slab will gain rigidity as temperatures cool Sunday night. The slab of concern will exist above a very thick crust and may release within the thin (approximately 2” layer) of old snow or at interfaces on either side of the layer. Watch for wind-loaded terrain where slab-like properties are more pronounced and navigate around unsupported or convex slopes and terrain steeper than 35 degrees.
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