Avalanche Forecast
Regions: Cascades - North East.
Updated: Storm slabs should become sensitive on Sunday but generally shallow in depth. During the afternoon, small loose wet avalanches involving the most recent snowfall will be possible on steep slopes. Watch for non-avalanche related hazards such as open creeks and barely buried rocks and trees.
Detailed Forecast
Updated northeast Cascades forecast 730 am Sunday morning.Â
Light snow is expected to turn to rain with a lull in precipitation Sunday morning for the central-east and southeast Washington Cascades. Light to moderate snow should continue for the Washington Pass area overnight with rain mixing in mid-day at Pass level. By late Sunday morning precipitation should once again increase and the cold front should push through in the afternoon as snow levels drop to 5000 feet by 4 pm. Â
Storm slabs should become sensitive on Sunday but generally shallow in depth. During the afternoon, small loose wet avalanches involving the most recent snowfall will be possible on steep slopes.
Watch for the numerous travel hazards such as open creeks, barely buried rocks and trees, and glide cracks, creating poor and challenging travel conditions, especially below treeline.Â
Remember that closed ski areas without avalanche mitigation are equivalent to backcountry terrain! Â
Snowpack Discussion
New resources within your Avalanche Forecast this season!Â
The Mountain Weather tab will take you to the most recently issued Mountain Weather Forecast. The Observations & Weather Data tab will allow an easy view of the various weather station graphs within your zone of interest and provide easy access to the most recent avalanche and snowpack observations.Â
The great start of winter 2017/18 in the PNW has taken a recent hit as warm wet weather arrived Tuesday morning and has just begun to cool as of late Thanksgiving. After some initial snowfall, the east slopes of the Cascades also received some heavy rainfall, with 2 to over 4 inches of rain since Tuesday morning, reaching well above the crest level.
Rain has now melted significant snow with average snow depths decreasing about 30-50% since Monday, especially at mid and lower elevations. This has allowed much of the previously well snow covered terrain to open with many creeks and snow bridges re-appearing, especially near and below treeline.
Cooler temperatures persisted in the Washington Pass area, where significantly less snow melt occurred. Lesser amounts were received elsewhere along the east slopes.Â
Cooling since Thursday with additional, mostly light precipitation, has begun to add some new snow above the old wet snowpack. The Washington Pass area received about 2-5 inches of new snow as of Friday afternoon.
Observations
See the recent observations tab for reports of several wet snow avalanches near the WA Pass area as a result of the warming and rain early last week.
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: All elevations.
Likelihood: Likely
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: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 1