Avalanche Forecast
Regions: Olympics.
The avalanche danger should mainly shift to new snow layers by the end of the daylight hours on Tuesday.
Detailed Forecast
A weakening cold front will cross the Northwest on Tuesday morning. This should cause light rain or snow with cooling temperatures.
Then a stronger short wave should cross the Northwest Tuesday afternoon and night. This should cause increasing rain or snow beginning in the Olympics Tuesday midday.
The rain mainly Tuesday afternoon should help small wet loose avalanches remain possible mainly near and below treeline on Tuesday. Watch for wet surface snow deeper than a few inches, pinwheeling of surface snow and small natural wet loose releases that usually precede more major wet loose snow avalanches.
New small wind slab should become likely starting Tuesday afternoon mainly above treeline on lee slopes. Watch for signs of cracking or firmer wind transported snow.
New small areas of storm slab should also become likely starting Tuesday afternoon also mainly above treeline on sheltered slopes. This is most likely in any areas that receive heavier snowfall.
In many areas the cooling trend may also bond new snow to old snow and build favorable stable new snow profiles.
Snowpack Discussion
A wet cold front 15-17 March stalled over the Olympics and the north Cascades and then produced mainly rain before changing to snow in a north to south fashion across the area. A favorable temperature trend with a gradual cooling occurred with this storm. The NWAC site at Hurricane picked up about 13 inches of snow late Saturday through Monday. This weather produced wind slab layers on north through east aspects near tree line and allowed for one skier triggered soft slab Sunday afternoon that covered the road.Â
Another cold front crossed the Northwest on Wednesday. This system produced more snow in the Cascades with the Hurricane Ridge weather station recording only about 4 inches of new snow at low temperatures and with generally light winds. On Friday afternoon NWAC observer Katy Reid denser wind slab on N thru SE near treeline that was stubborn in stability tests and did not note in any recent avalanches.  She also observed widespread surface hoar from Thursday night along with graupel as being preserved under cool temperatures and light winds but this was reported as destroyed by the end of the weekend.
On Sunday Katy reported numerous small to large wet loose avalanches on solar aspects but dry loose avalanches on due north aspects at higher elevations.  She also found wind slab in the limited above treeline zone near Hurricane Ridge to be prone to snowpit test failures down 20 cm at a melt freeze crust on the colder N-NE aspects.
Wet loose conditions are expected to be continuing on this warm Monday on solar slopes.Â
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.
Elevations: Treeline, Below 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, South East.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1
Storm Slabs
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: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1