Avalanche Forecast
Regions: Cascades - South West.
Although less likely, the primary avalanche problem Thursday will continue to be loose wet avalanches.
Detailed Forecast
Mild snow levels will prevail again on Thursday with light rain developing for the central and north Cascades. There may be a few sunbreaks for the south Washington Cascades Thursday.Â
Loose wet avalanches are possible Thursday on steeper slopes near and above treeline that either receive enough rainfall, or in areas further south, solar aspects that receive substantial sun breaks. If neither happen, the loose wet avalanche potential would be minimal.  Â
Lingering wind slab will be listed as a problem for one more day west of the crest above treeline. Watch for firmer wind transported snow on previous lee slopes mainly on N-SE slopes near ridges.
As a result of the overall low snowpack, especially below treeline, watch for terrain hazards such as open creeks, partially covered rocks and vegetation.
Snowpack Discussion
The latest atmospheric river to impact the Pacific Northwest brought several inches to around a foot of water to the west slopes last week; unfortunately it fell mostly in liquid form. This lead to significant settlement and at lower elevations, continued melting of the seasonal snowpack.  Â
About 5-12 inches of heavy snow was seen near and above treeline the past couple days west of the crest based on weather station data and reports.
Signs of loose wet activity that began Tuesday was dampened by extensive high cloud cover on Wednesday. Despite the continued warmth and high freezing levels, several NWAC observers along the west slopes Wednesday reported no avalanche activity in the below and near treeline zones. The most recent storm snow in the upper snowpack near treeline was reported as wet and well bonded to the previous rain crust. Â
The mid and lower snowpack west of the crest should consist of layers of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this winter.
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: All aspects.
Elevations: All elevations.
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.
Likelihood: Unlikely
Expected Size: 1 - 1