Avalanche Forecast
Regions: Olympics.
You can still trigger a large or small stiffening wind slab on Sunday. You are most likely to trigger a wind slab near ridge-line on a polar aspect. Use visual clues such as snow drifts, cornices, and firm snow with cracking to identify and avoid wind-loaded areas.
Detailed Forecast
Light snow will fall at times on Monday and moderate W-SW wind will transport the very shallow new snow in addition to dry snow on northerly slopes to build small, fresh wind slabs that may be reactive on Monday. Watch for signs of wind actively transporting snow including drifts or wind pillows wind-scoured ridgelines and navigate around steeper lee slopes receiving such transport.
You can also still trigger an older wind slab that is likely to be stiff,  gradually healing, and small to large in size. You are most likely to trigger these below on convex rollovers and steep, unsupported slopes near ridgelines, particularly where recent cornices have formed.
Snowpack Discussion
A skier triggered a Wind slab late in the day Friday night or early Saturday morning. These wind slabs were formed by moderate to strong southerly winds redistributing 10" of new snow that fell Thursday through Friday forming wind slabs on northerly aspects near and above treeline and stripping snow off of exposed southerly aspects.
Several days of mostly sunny weather created a breakable melt-freeze surface crust on solar aspects with 5" of lower density snow underneath. On polar aspects, the snow remains dry and potentially available for wind transport during the next storm. The loose surface condition resulted in three small loose dry avalanches on 3/23.
The new snow sits on a variety of old snow surfaces. On slopes that received direct sun during the recent clear weather, a firm and thick melt-freeze crust can be found. On shaded slopes a thinner more breakable crust has been observed.
Weaker layers of sugary facets and thin crusts have been found within the snowpack. Current observations suggest that these weak layers are not widespread. You are most likely to find older weak snow on East facing slopes about 1 ft (30cm) below the snow surface.
There are no other significant layers of concern in the snowpack at this time.
Observations
On Saturday, NPS rangers reported a small skier-triggered wind slab (40 ft wide, running 80 ft) wide on a north-facing aspect. North-facing aspects preserved soft snow.
Chalky-textured wind-loaded pillow near ridge-line adjacent to the skier-triggered wind slab. Photo credit: Sarah Crosier, Hurricane Ridge NPS
NWAC observer and NPS rangers on Thursday, 3/22 found blowing snow actively building fresh cornices and wind slabs above 5000’. Slabs were generally shallow (6-8â€, 15-20cm) but were observed upto 1 foot (30cm) thick. Exposed windward slopes were often stripped of the new snow down to a firm and hardening crust.
Avalanche Problems
Wind Slabs
Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1