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RegisterApr 1st, 2018–Apr 2nd, 2018
Olympics.
You may be able to trigger fresh and shallow Wind Slabs on lee slopes in the Hurricane Ridge area Monday as well as Persistent Slabs on shaded slopes at mid to upper elevations. Persistent Slabs are difficult to manage and can break in surprising ways. Make sure to avoid avalanche terrain where new Wind Slabs and older Persistent Slabs likely overlap, such as N-E aspects near and above treeline.
An increase in clouds Monday afternoon should limit daytime warming with unusually cold temperatures expected for early April. On Monday, you may be able to trigger fresh and shallow Wind Slabs near and above treeline in the Hurricane Ridge area, especially on NW-N-E-SE aspects. Use visual clues such as snow drifts, cornices, wind textured snow, and firm snow surface conditions that produce cracks to identify and avoid wind loaded areas.
You may also be able to trigger Persistent Slabs on shaded slopes at mid to upper elevations. Persistent Slabs are difficult to manage and can break in surprising ways. To stay safe, avoid where the problem exists.
Make sure to avoid avalanche terrain where new Wind Slabs and older Persistent Slabs likely overlap, such as N-E aspects near and above treeline.
Up to 4 inches of low density snow accumulated in the Hurricane Ridge area by 4 pm Sunday with temperatures dropping in the afternoon. Prior to Sunday's frontal system, temperatures had warmed over the preceding days with mild daytime temperatures. Benign weather this week has allowed for snowpack settlement and the development of a strengthening melt freeze crust.
Slab avalanches released early last week, likely failing on a weak layer above a strong melt-freeze crust buried about 1.5 ft on lee slopes above Hurricane Ridge. This layer has been tracked over the past few weeks but has now produced at least two slab avalanches, each with crown depths about 1.5 ft and propagating over 100 ft wide on NE aspects between 5200-5400 ft.
There are no other significant layers of concern in the snowpack at this time.
Observations
No new avalanche activity was reported in the Hurricane Ridge area over the weekend.
On Friday, NPS Rangers performed snowpack tests on a NNE aspect at 5,000 ft. They reported test results indicating propagation on a layer of weak old snow about 2 ft below the surface.
On Thursday, 3/29 NWAC professional observer Matt Schonwald saw evidence of two recent slab avalanches releasing on steep convexities on NE aspects between 5200-5400 ft. These avalanches released on a weak layer, poorly bonded to a hard crust. Several snowpack tests on this layer confirmed the propensity for avalanches to propagate.