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Avalanche Forecast

Archived

Jan 1st, 2020–Jan 2nd, 2020

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

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The avalanche danger you encounter Thursday depends on how much new snow you find. When you come across more than 8 inches of heavy storm snow or find the wind formed snowdrifts, steer around all open slopes greater than 35 degrees. If you discover evidence of strong over weak snow at lower elevations, you can expect the same issue to be larger and harder to manage as you ascend.

Discussion

The combination of heavy snowfall and sustained strong and extreme winds above treeline makes dangerous avalanche conditions a sure bet at these elevations. Elsewhere, a Puget Sound Convergence Zone (PSCZ) developed at times on Tuesday and has re-developed over the Mountain Loop region Wednesday evening and is forecast to shift southward overnight. We don’t know exactly where convergence will set up, so check a 24-hour radar loop (available from the UW department of Atmospheric Sciences) to estimate where heavier precipitation has focused.

Remember that early season conditions exist below 4000 ft in many areas and creeks are still widely exposed due to the recent warm rain events. Factor these travel challenges into your tour plans.

Snowpack Discussion

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

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). 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.