Avalanche forecast

East Slopes South

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Sunday's storm brought a widespread crust followed by fresh snowfall. Your risk of triggering a small wind slab is heightened on steep, lee slopes. Note the aspects scoured to a crust and anticipate wind loading on the opposite aspect where you should avoid slopes steer than 35 degrees. 

Avalanche problems

  • Wind Slabs

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

    Most of the zone likely picked up 3-6" of new snow, with slightly higher totals close to White Pass.  The snow fell right-side-up and we suspect a decent bond with the underlying crust. Your risk of triggering a wind slab increases as you move into exposed terrain. Look for areas scoured down to the crust and test wind-loaded pillows for reactivity. These are likely to have a firm over weak snow structure. Steer around steep wind-loaded start zones beneath freshly corniced ridgelines, lens-shaped pillows, or areas of wind-stippled snow. At middle elevations, you might only have enough snow to trigger a slab in the most wind-loaded and exposed locations.

    Example: Rippled, uneven snow surfaces indicate snow was transported by wind. 

    Photo: Payton Schiff

Avalanche Discussion

In some areas near the Cascade Crest, you might encounter more than 8" of snow above the crust. In these rare locations, consider whether there might be a more widespread lingering storm slab problem in your area.  Consider quickly isolating the snow above the crust as you ascend in the terrain to gauge slab reactivity.

On 12/8: An observation just east of White Pass reported around 8" above the crust with some reactivity within the storm snow. An observer around White Pass reported around 6" of new snow. Therefore, we expect that most locations are below the threshold for more widespread storm slabs.

Monday will be sunny and cool in the East South zone. The snow may still start warming up in shallow snowpack areas near rocks and as snow sheds off trees. This typical shedding could create very small wet loose activity on very steep slopes receiving direct sunshine. Take note of the slopes above you and your exposure.

In contrast to other parts of the Cascades, most weather stations reported little or no new snow or rain until Saturday evening. Minimal liquid water will help keep most of the snow on the ground and some that fell likely arrived as freezing rain in colder valley locations. It also means there will not be much of a crust, at least on slopes that didn't see much sun last week. Without much of a crust, faceted snow and surface hoar - at the snow surface prior to the storm - might be under the new snow in some locations.  Keeping this in mind, don't ignore obvious signs of instability like shooting cracks, whumphing, or recent avalanches. Take a conservative approach until you get a feel for conditions wherever you are in the mountains.

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