Avalanche forecast

East Slopes North

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Strong winds and new snow will develop dangerous avalanche conditions at upper elevations. You could easily trigger large avalanches in wind drifted snow. Avoid steep open slopes with stiff wind-drifted snow and seek out lower angle or sheltered terrain instead.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2

    Strong winds and a significant storm will impact the Cascades on Wednesday. Expect peak precipitation to occur during the day, with increasing wind speeds. Plenty of snow is available for transport, and the storm will bring plenty more snow over the Cascade crest to the east slopes of the Cascades. Winds are forecasted in the 25-35mph range and will easily drift snow around, even at lower elevations. So any steep open terrain will potentially harbor large wind slabs. But avoiding these wind slabs in alpine terrain will be especially challenging. So while the storm pummels the mountains, avoiding steep, wind-exposed terrain at all elevations will be best. Simple, low-angle slopes will be the best option to reduce to likelihood of triggering an avalanche. The most likely places to trigger wind slabs will be steep slopes below ridges, steep convex rolls, and the base of cliffs. Feel for stiff over soft snow layering and look for signs of cracking or collapsing to identify and avoid areas of unstable wind-drifted snow. Cold temperatures may have created weak snow surfaces. Therefore you could find reactive storm slabs on steep slopes in sheltered areas. You can use small, inconsequential test slopes and quick hand pits to observe how the new snow reacts. Avoid steep terrain if you find the new snow sliding easily or test slopes producing mini avalanches.

    (3/1/2023)

    Cracking in a small wind slab. These shallow slabs were reactive on Wednesday. 

    Photo: Willie Webster

Avalanche Discussion

NWAC observer Willie Webster found shallow reactive wind slabs on Wednesday. The sun was a short-lived visitor, and soft snow and wind-affected surfaces were the primary surface conditions. He also identified weak snow below the Valentine's Crust that was very reactive in snowpack tests, and he experienced some isolated collapses on this layer. He noted the instability seemed isolated to the 4000-5000ft elevation band. This crust can be found up to 7,000ft in the zone and varies with elevation and proximity to the crest. While we have not seen any avalanche activity on this layer, we are closely monitoring this interface as snow buries it deeper. Over the last week, large cornices have failed. With additional wind and snow, these behemoths will only grow larger and potentially more sensitive. They are a hazard on their own but also could trigger an avalanche as they land on steep slopes below. Best to give these hazards wide margins as you travel. 

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