Avalanche Forecast
Regions: Snoqualmie Pass.
Unstable storm and wind slabs should persist above treeline Monday, but begin gradually settling. Wet snow should slowly refreeze below treeline with shallow new snow forming a good bond.
Detailed Forecast
The storm over the weekend should be in the rear view mirror by Monday, as high pressure rebuilds.  This should cause light to moderate northwest crest level winds and little if any accumulation of new snow.  Temperatures should remain cool Monday.
Recent storm and wind slabs should persist at higher elevations, especially above treeline and near ridgetops. Best to perform numerous quick test pits or pole tests to determine recent snow conditions. The cooler temperatures Monday should continue to slowly refreeze the old rain soaked snow surface to limit avalanche potential at lower elevations.Â
Snowpack Discussion
A very strong storm began affecting the region Friday. Â This system deposited varying amounts of new snow ranging mainly from 5-10 inches below treeline to 1-2 ft or more near and above treeline by Saturday afternoon. Â Freezing levels rose significantly Saturday night and early Sunday changing snow to rain in most areas, at least to the near treeline zone and in many areas above that.
The rain has changed the landscape of the snow conditions by Sunday. The rain likely caused some natural avalanches Saturday night in areas with significant recent snow.  Little field information has been available Sunday, however expect lower to mid elevations to begin slowly refreezing and forming a new crust with shallow amounts of new snow being well bonded to the old surface.
The overall still shallow snowdepths are maintaining many terrain anchors (trees, rocks, etc.), preventing large avalanches. Â
Above 5000' to the top of our forecast range (7000-8000 ft)... snowdepths are still seasonally well below average, but are deep enough to provide a bed surface for new snow avalanches from the current storm snow.  Generally, there is 3-5 foot base above 5000', deepest in the North Cascades and at Mt. Rainier.  Expect a shallower snowpack in the Stevens-Snoqualmie zones and south of Mt. Rainier.
In the upper elevations above treeline, expect some deep storm or wind slabs, especially in areas that have received the greatest precipitation over the past few days.
Avalanche Problems
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
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