Avalanche forecast

Central Cascades

Central Oregon Avalanche Center
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Avalanche danger

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

Triggering avalanches will be likely on Sunday in areas where the wind has deposited snow, especially near ridge tops and at upper elevations. In the trees, avalanches will be possible if 8 or more inches of snow accumulate, or if the precipitation turns to rain and the snow surface becomes wet and slushy. Avoid these avalanche problems by monitoring where the wind is blowing snow, how much new snow is stacking up, or by sticking to slopes that are less than 30 degrees. 

Avalanche problems

  • Wind Slabs

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

    With 6-8 inches of new snow possible overnight and moderate westerly winds, triggering wind slab avalanches that are large enough to bury, injure, or kill a rider will be likely at mid and upper elevations on Sunday.  Even as the precipitation rate and wind speeds taper on Sunday, continue to keep an eye out for blowing snow, and a rippled or pillowy snow surface. Open terrain below ridge tops and convex rolls are likely places to find wind slabs. It's also a good idea to give cornices a wide berth on Sunday, as they may be fragile with all the wind, rain, and snow we've gotten in the past few days. If you're uncertain, move to wind-sheltered or low-angle terrain that's less than 30 degrees. 

    At Tam MacArthur Rim on Saturday, I found a few small pockets of wind slab on north and east aspects. Notably, I found these slabs on steep terrain features below treeline. These slabs were shallow and soft (they broke apart easily), but they had the characteristic rippled surface of wind-transported snow. This told me that at higher elevations where there's less wind protection and more open terrain, I should expect to find bigger and more cohesive wind slabs. 

  • Storm Slabs

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

    Anticipating a storm slab problem on Sunday is tricky, because it will depend on how much snow accumulates and whether the precipitation remains as snow or changes to rain as temperatures warm. Some weather models are calling for as much as 10 inches of snow between Saturday night and Sunday afternoon, while others are calling for a mix of rain and snow. If we get the higher end of the snow totals plus a warming trend, that is a recipe for storm slab avalanches. 

    You can monitor this avalanche problem by tracking how much new snow falls. If we get 8 or more inches of snow, pay close attention to how the new snow is bonding. You can use your ski pole to probe into the snow and check for changes in density (strong over weak) or to cut a small block and do a hand shear. 

Avalanche Discussion

If the precipitation turns to rain, you'll want to turn your focus toward wet avalanche problems. Snowballs that form on the snow surface and roll down slope are an early indication of a loose wet avalanche problem.  

If you see signs of instability in the snow surface, move to lower angle terrain and avoid terrain traps, like tightly packed trees, cliffs, gullies, and depressions, where the consequences of an avalanche will be worse. 

Regions covered