Avalanche Forecast
Regions: Cascades - West.
Quite a difference in avalanche problems should be seen along the west slopes on Monday with a greater avalanche danger at Mt Baker.
Detailed Forecast
Frontal moisture should mostly lift north to BC  Sunday night to Monday afternoon. A chance of light rain or snow will be forecast for Monday for the northwest Cascades which should not greatly change conditions. Fair weather is expected elsewhere in the Cascades Monday with warmer temperatures mainly in the south Cascades.
Mt Baker Area: Several or more inches of new snow is expected above treeline at Mt Baker on Sunday. This means you will need to watch for likely new loose wet and new storm and wind slab conditions above treeline at Mt Baker on Monday. The rain at Mt Baker near and below treeline on Sunday will also add water to surface snow layers.
Likely loose wet avalanches will be emphasized on solar slopes but watch for loose wet conditions on all aspects. New storm slab may linger on a wider variety of aspects above treeline. New wind slab will be likely above treeline on lee slopes.
Elsewhere west of the crest: Recent snow and wet snow has had a chance to slightly consolidate and partly stabilize elsewhere west of the crest. Possible loose wet avalanche should be the main problem in most of this area and will also be emphasized on solar slopes but watch for loose wet conditions on all aspects.
Older wind slab may linger on previous lee slopes. Watch for possible firmer previously wind transported snow mainly on north to east aspects.
All areas west of the crest: Cornices won't be listed as an avalanche problem. But avoid slopes below cornices and ridges or summits where cornices may be hard to see in all areas.
Snowpack problems west of the crest for the time being should be in the upper or surface layers. The mid and lower snowpack west of the crest consists of layers of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this winter. Many areas at the lowest elevations do not have enough snow to cause an avalanche danger.
Snowpack Discussion
Winter made a bit of a comeback in the Northwest in mid to late March. Several storms or storm cycles brought a lot of water and heavy snow to the above treeline areas west of the crest especially on the volcanoes. This caused slab avalanches and loose wet and loose dry avalanches at times with a couple involvements including in the closed Crystal Mountain Ski Area - see the March 24th report via NWAC Observations.
A warm front caused pretty heavy rain mainly west of the crest Wednesday to Thursday morning. This caused an avalanche cycle and consolidation west of the crest with the most avalanches at Mt Rainier.
Slab avalanches in the Tatoosh Range from March 25th. Photo taken March 26th by Andrew Carey.
A vigorous front and short wave crossed the Northwest Friday night causing strong west-southwest winds, some rain and snow and lowering snow levels. Snow levels lowered enough by Saturday to cause up to 2-3 inches of snowfall at higher NWAC stations west of the crest and likely a few more inches at higher elevations.
Frontal moisture is moving mainly to BC Sunday and there is quite a difference in the weather between the Mt Baker area and elsewhere in the Cascades. The NWAC station at Mt Baker has already seen a lot of rain today which should be snow above 5-6000 feet. But fair conditions are being seen elsewhere in the Cascades Sunday.
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, South East.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 1