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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Steep rollovers or other types of unsupported terrain are where you are most likely to trigger an avalanche. Use planar and/or lower angle terrain to navigate around these features and reduce risk. Deeper snow and thus  greater avalanche danger can be found south of Highway 2. Check the forecasts for Stevens and Snoqualmie Passes if you are traveling near these zones.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Existing wind slabs will be the greatest hazard on Thursday. If northeast winds are stronger than forecast, expect to see abundant loose snow transported into new slabs. Take a step back in your terrain choices if you observe active wind loading.

    The current crop of slabs could be difficult to identify with a powdery surface layer hiding signs of recent wind loading. Use cornice like features to identify the loading pattern during the latest storm. Monitor new snow depth in sheltered areas and use this as a reference in more wind exposed terrain. Shallower new snow or a firmer surface at or just below the snow surface is a great indicator of lurking wind slab.

    Simple hand pits let you investigate the relative difference between wind stiffened layers and weaker snow below. Test slopes - especially on wind drifted features - can give you an idea about the reactivity of wind slabs in the immediate vicinity (photo).

    There is still quite a bit of new snow out there. Stay alert in lower elevation terrain and keep assessing new snow layers. Don't forget about the consequencse of exposed terrain obstacles, open creeks or gullies below.

    Long shooting cracks in freshly wind drifted snow are reliable  indicators that a reactive wind slab exists nearby.

    Photo: Matt Primomo

Avalanche Discussion

Once again snowfall amounts varied a bit across the zone. West North ranged from 12" to 19", Mountain Loop averaged a bit over 12" and Stevens Pass with 20". Snoqualmie Pass won the prize with over 24". While some natural and human triggered avalanches were reported from all corners of the Cascades, they tended to be small and released within new snow layers. Larger avalanches to D2 were noted in wind loaded terrain and some likely ran at the new/old snow interface. 

The lack of large scale (or sized) avalanche activity points towards a strong snowpack. On the other hand, one team in the Baker Backcountry in West North experienced a single large whumph near treeline on Wednesday. A nearby snowpit indicated rounding facets between crust layers +100cm down (photo). No similar instability or snowpack observations were noted in the past week. Observations like this remind us to not take the snowpack for granted, especially during colder weather when weak snow is more likely to develop and linger.

One person was fully buried - but quickly recovered - in a short, steep gully feature in backcountry terrain adjacent Mt. Baker Ski Area. Details are sparse, but it appears it was a small loose dry triggered either by the victim or someone above. Though this avalanche was very, very small, it still highlights both the need to be aware of terrain traps below and good communication with those around.

If you are out and about in the mountains, let us know what you find by submitting an observation. 

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