Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

New snow and cooling temperatures are in the forecast after many, many inches of rain. Avoid pockets of freshly wind-drifted snow if traveling at mid and upper elevations. Steer clear of areas below snowy cliffs and steep terrain with running water that can still shed snow or rocks.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Fresh snow combined with moderate to strong wind can build unstable slabs. New snow amounts could vary greatly across the forecast zone with some areas seeing up to 8" while others see only an inch or two. Slab formation is most likely at upper elevations. But look for unstable pockets anywhere you observe active or recent wind transport. Use test slopes and hand pits to see how well new slabs are bonded to the layers below. 

    Observations are minimal and uncertainty is high at upper elevations when it comes to recent avalanche activity, snowpack structure, and the amount of dry snow available for transport. If you do make it up there on Thursday, be prepared to make your own assessment. Anticipate larger slabs where there is more dry snow at the surface to drift onto leeward slopes.

    Example of smooth wind slab on the left and scoured snow on the right.

Avalanche Discussion

The likelihood of continued wet avalanche activity should be lower on Thursday due to less precipitation and gradually cooling temperatures. It’s still wise to avoid spending time below rugged terrain like waterfalls, rock faces, and steep, brushy cliffs holding snow. Wet avalanches and rockfall can still initiate from these features.

With wet, soggy conditions and poor snow quality, folks aren’t exactly lining up to get into the mountains. The few who were out today in neighboring zones reported no new avalanche activity and punchy, hollow snow in some areas.  West Central weather stations recorded an additional 0.5 to 1.6" of precipitation (rain) in the last 24 hours. The White Chuck Tripod showed a 45% reduction in snow height to 26" after reaching a season-high of 47" over the weekend.

A profile on Dec 5th at 4400’ in West North showed a thoroughly rain-affected snowpack with alternating layers of melt forms and moist rounds. The weak layer responsible for Saturday’s avalanche activity (link, link) was not found. The snow surface at mid-elevations is heavily runneled and will make for a variable, uneven crust when it freezes. Lower elevation and some mid-elevation locations have minimal snow and difficult travel. 

 

 

 

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