Avalanche Forecast

Archived

Dec 23rd, 2018–Dec 24th, 2018

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 unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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The Mountain Loop area received significant new snow on Saturday night and Sunday. The storm slabs formed during this event are healing, but this takes time. You are most likely to trigger an avalanche as you go up in elevation, into areas affected by the wind, or on convex rollovers. We have no recent observations from this zone and the associated uncertainty should reduce your terrain selection.

Discussion

Avalanche Summary:

We haven’t received any recent observations of avalanches in Hwy 542 area, but visibility has been limited. To the south and east, a small wind slab avalanches were reported on an exposed slope at high elevation on 12/22 while storm slabs were becoming more reactive at Snoqualmie Pass with at least six observed 8” storm slabs triggered naturally or by humans on steep or unsupported slopes.

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.