Avalanche Forecast
Regions: Olympics.
Limited snow will limit the avalanche danger in most areas of the Olympics on Tuesday. But the cool somewhat snowy weather may bring a variety of changeable March snow and avalanche conditions above treeline.
Detailed Forecast
Some light snow showers may be seen in the Olympics on Tuesday with fairly snow levels.
The cool somewhat snowy weather may bring a variety of changeable March snow and avalanche conditions.
We are past the equinox and the sun is rapidly getting stronger and new snow will be susceptible to sun effects. Watch for wet snow deeper than a few inches or snowballing or natural loose wet avalanches by Tuesday midday on solar slopes. This should be mainly ATL in the Olympics where there might be significant recent snow.
Previous wind slab may linger on lee slopes mainly ATL where there is significant snow. Use extra caution near slope convexities where storm or wind slab avalanches are more likely to be triggered.
Most areas below treeline in the Olympics do not have enough snow to cause an avalanche danger.
Snowpack Discussion
The 16-18 inches of storm snow that fell a week ago has all but melted at Hurricane Ridge. The total snow depth at the NWAC weather station has settled or melted and lost 10 inches over the past week.
Just a few inches of new snow accumulated late last week and over the weekend. Winds may have built some small cornices along ridges and transported snow to build some small wind slabs on lee slopes.
A weak upper short wave and unstable air mass is moving over the Northwest on Monday. This should slightly favor the Cascade volcanoes for snow showers. Another rapidly moving shortwave will carry a surface low across the north Oregon Cascades Monday night. This should renew snow showers Monday night in the south Cascades with possible overnight stormy conditions at Mt Hood. So the main weather action is mostly bypassing the Olympics on Monday and Monday night.
Avalanche Problems
Loose Wet
Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.
Several loose wet avalanches, and lots of pinwheels and roller balls.
Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.
Aspects: South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1
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: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1