Avalanche Forecast
Regions: Olympics.
The avalanche danger will decrease Wednesday with cool and cloudy conditions expected. Shallow new Wind Slabs may linger near and especially above treeline Wednesday. You can avoid triggering these avalanches by steering around steep roll-overs, unsupported features, and obvious start zones where you suspect Wind Slabs. A strong March sun affects the snow rapidly and can quickly create a Loose Wet avalanche danger if the sun comes out for an extended period of time.
Detailed Forecast
The avalanche danger will continue to decrease on Wednesday with cloudy weather and a chance of a rain or snow shower. Some sun breaks are possible.
Shallow Wind Slabs may linger near and especially above treeline Thursday, but are continuing to heal rapidly under warm temperatures during the day on Wednesday. You may be able to trigger a Wind Slab avalanche at upper elevations on steep slopes near ridge tops or in cross-loaded terrain features. Watch for clues like variable snow height, drifts, cornices, and stiff snow that produces cracking. These are all indicators that you could trigger a Wind Slab. You can avoid triggering these avalanches by steering around steep roll-overs, unsupported features, and obvious start zones where you suspect Wind Slabs.
Small Loose Wet avalanches will not be listed as a problem but are still possible in isolated terrain features such as steep sunny slopes below treeline if the sun pops out for an extended period of time. Watch for warning signs like new roller balls, pinwheels, and natural Loose Wet avalanches that indicate increasing hazard. Even small Loose Wet avalanches may carry you into terrain with high consequences such as over cliffs or into gullies.Â
Snowpack Discussion
Temperatures have warmed over the last several days and there were no significant snowfall accumulation Tuesday at Hurricane Ridge. Minimal snow transport. Temperatures rose above freezing as the precipitation ended in the afternoon, likely creating a thin rain crust to around 5,000 ft.Â
A skier triggered a Wind Slab avalanche late in the day Friday or early Saturday morning. Wind Slabs were formed by moderate to strong southerly winds redistributing 10" of new snow that fell Thursday through Friday. Wind slabs were found on northerly aspects near and above treeline and stripped snow off of exposed southerly aspects.
Weaker layers of sugary facets and thin crusts have been found within the snowpack. Recent 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.
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