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Archived

Avalanche Forecast

Jan 20th, 2020–Jan 21st, 2020
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
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
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Cascades - West.

Freezing levels begin to lower and there is a return to precipitation Tuesday. Avalanche activity will increase throughout the day, particularly at upper elevations where any precipitation should be predominantly snow. Avoid being on or under avalanche terrain if you see obvious signs of instability such as recent avalanches or shooting cracks.

Snowpack Discussion

New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.

Avalanche Problems

Storm Slabs

Storm slabs may develop at all elevations Tuesday as snow levels lower and precipitation falls on the surface crust created over the weekend. Winds may deposit new snow on lee slopes, creating thicker and more reactive slabs. Use small test slopes and hand-pits to investigate the bond between the new snow and the existing surface. If you find a poor bond and more than 6 inches of cohesive snow, avoid slopes greater than 35 degrees. At lower elevations, heavy snow may exist, with avalanches possibly more wet loose in nature.

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