Avalanche Forecast
Regions: Snoqualmie Pass.
The avalanche danger should continue to slowly diminish Tuesday for previous storm layers. However, warming and sunshine later Tuesday should increase wet snow on southerly facing terrain.
Detailed Forecast
Precipitation should end by early Tuesday as skies clear from the south and freezing levels climb. Â Moderate northwest crest level winds should gradually ease through the day Tuesday. Â This weather will help to settle and consolidate the large recent storm snow deposits and lead to a slowly stabilizing snowpack. Â However warming and sunshine by late Tuesday may lead to some shallow wet snow conditions and possible loose-wet slides on steeper solar aspects. Â
At elevations above treeline, earlier formed wind slab should be somewhat slower to stabilize so continued conservative decision making and cautious route finding will remain essential.  These earlier formed wind slabs near ridges in the alpine region should remain the greatest concern, most probably on north through southeast facing slopes. Rather large wind slab releases may trigger more deeply buried weaknesses near or above old crust interfaces and this may lead to very large slides, though natural slides should become less likely and triggered slides should also become more stubborn to trigger, it remains a time to be extra cautious.
Snowpack Discussion
A nearly week long storm cycle began last Tuesday and should be waning Monday night as skies begin clearing under a return to high pressure. This major storm cycle has packed some fairly impressive numbers, especially for this season.  Five day storm snow amounts range on average from 60-150 cm both, with the lower amounts confined to lower Cascade passes where more rain occurred.  Most mid and higher elevation areas received 1-2 m of storm snow. Â
Needless to day this produced several avalanche cycles producing numerous natural and triggered slides over the past few days. Â Freezing levels fluctuated significantly and there were also periods of very very strong winds. Â This culminated in some new denser layers or crust layers as well as buried weak lower density layers within the deep storm snow. Â
Most recent avalanche activity either, natural, ski or explosive triggered has remained within storm snow layers, ranging from 15-60 cm. However, some slides released on a buried weak lower density layer above an earlier formed crust layer down some 60-120 cm or more depending upon locale.  Recent field obs from Sunday near Stevens Pass on a lee slope just above 5000 ft showed wind loaded storm snow of 1.2 m. The NWAC station at Paradise on Mt. Rainier became the first station this season to finally cross the 100 inch threshold during this storm. Â
There were several reported soft slab releases Friday in the Mt Baker backcountry, felt to be releasing on a weaker lower density storm snow layer above a previous crust layer. However the snowpack has significantly changed with recent additional loading, warming as well as significant overall settlement helping move towards slow stabilization.  There were numerous new natural and triggered slides near Mt Baker on Shuksan arm and vicinity Sunday with slides on Shuksan estimated with Destructive potential 3 (destroy a wood frame house!).  Another natural release was reported early Sunday afternoon that likely released late morning during warming and heavy loading east of Stevens Pass.  The slide path is known as West Camp of Rock Mountain and was rated as D3/R2 N-SS, with a start zone about 5900 ft but poor visibility limited viewing. Â
An NWAC observer in the Stevens Pass area Sunday reported sensitive storm slab with shooting cracks below treeline and good wind transport on higher N thru SE slopes. Â
For the west slopes of the Cascades and Olympics, a generally favorable mid and lower snowpack exists, even if well below seasonal norms, consisting of various crust layers, rounded grains, and melt-freeze crystals. Â
Sno-cat triggered 5' crown - E aspect - 5700 feet - White Pass In Area Sunday (Photo by Chris Talbot)
Shooting cracks in Storm Snow 4800' - SE Aspect - Stevens Pass (Photo by Dallas Glass)
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: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2
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: Possible
Expected Size: 1 - 1
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: All elevations.
Likelihood: Possible
Expected Size: 1 - 1