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Archived

Avalanche Forecast

Dec 30th, 2019–Dec 31st, 2019
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Olympics.

Dangerous avalanche conditions will likely develop by the end of the day Tuesday and continue Tuesday night as a powerful storm impacts the region. Loose wet avalanches will become increasingly likely at lower and mid elevations. Slab avalanches are more likely at upper elevations and will be larger on lee slopes with wind drifted snow.  

Discussion

Tuesday looks like a wet and windy day at Hurricane Ridge as a storm system rolls through. Wet snow avalanches are the most likely problem you'll encounter but if the storm stays colder than forecast with more snow than rain, be prepared for storm slab avalanches lower in the terrain. 

Forecast Schedule

For the 2019-20 winter season, avalanche danger ratings will be issued for the Olympics every Friday through Sunday and during mid-week holidays. During the week, No Rating will be issued but forecasts will include expected conditions and relevant travel advice.  If you are out in the Olympics, share your backcountry observations with us and the greater community.

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. 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 upper elevations 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: Alpine.

Likelihood: Possible

Expected Size: 1 - 1