Avalanche Forecast
Regions: Cascades - South West.
Expect dangerous avalanche conditions to develop during the day and continue Tuesday night as a powerful storm impacts the region. Loose wet avalanches will become increasingly likely at lower and mid elevations as snow changes to rain. Slab avalanches are more likely at upper elevations and will be larger on lee slopes with wind drifted snow.
Discussion
A warm and windy storm system will impact the area on Tuesday with potentially a wide range of weather outcomes driving how quickly avalanche conditions change across the zone. If the Crystal area is blocked and sees significantly lower precipitation totals than Paradise, expect a lower avalanche danger in this area. In addition, the potential for a period of freezing rain in the White Pass area on Tuesday would also lower the avalanche danger in part of the zone. However, this storm shakes out, expect wet snow avalanche problems to climb in elevation as the day wears on.Â
Fresh observations from the White Pass area suggest that recently buried weak snow only a few inches from the surface may have been destroyed over the last few days. New storm slabs that develop on Tuesday may fail within new storm layers or break down to this interface in areas it has been preserved. Much deeper in the snowpack, we are continuing to track a persistent weak layer about a foot above the ground on W-N-E aspects above 5800â in the Crystal and White Pass areas. This interface has been dormant since the last major storm cycle, but we will continue to think about the potential for very large avalanches as we get deeper into this storm cycle.Â
Due to low snow depths, difficult travel conditions and early season hazards are still a factor at all elevation bands.Â
Snowpack Discussion
New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.
Avalanche Problems
Loose Wet
Any new snow that falls prior to a change to rain will become available for loose wet avalanches with larger avalanches likely at upper elevations. If you see rollerballs, pinwheeling or natural loose wet avalanches, avoid nearby steep slopes where you find wet unconsolidated surface snow. Wet loose avalanches are often more powerful than you'd expect. Avoid extreme terrain where even a small avalanche could rake you through rocks, stumps or push you into open creeks.
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
Storm Slabs
Depending on how quickly the rain line pushes up in the terrain, new storm slabs may develop at all elevations and with thicker slabs building on wind loaded lee slopes. Avoid slopes steeper than 35 degrees with freshly drifted snow. Watch for signs of unstable snow like shooting cracks as you travel. Avalanches that start as slab avalanches higher in the terrain can become wet, heavy and powerful as they travel to lower elevations.
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