Avalanche Forecast

Archived

Dec 24th, 2019–Dec 25th, 2019

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Stevens Pass.

Happy Holidays! If you get out to try your new toys, remember that avalanches are still possible at upper elevations where the snow is dry. Expect difficult and potentially dangerous travel conditions due to refrozen crust at lower elevations.

Discussion

Happy Holidays from all of us at NWAC! The recent atmospheric river event left 3ft of settled storm snow on the ground at Stevens Pass. A widespread, large avalanche cycle was reported from all elevations on the 20th and 21st. Rain was observed up to about 5,000ft. As a result, a sometimes breakable, sometimes supportable, but now frozen melt freeze crust can be found up to mid 5,000ft throughout much of the zone, making travel difficult at these lower elevations.

If you venture further east in the zone, check out the East Central Zone forecast, as we have a persistent weak layer there. Watch this video I put together from my field day in the Icicle drainage on the 23rd for more.

Cold nights, mostly clear skies, and some humidity are good conditions for surface hoar growth. December 24, 2019 in the Skyline area. Joseph Dellaporta photo.

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.