Avalanche forecast

Central Cascades

Central Oregon Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

The avalanche danger on Wednesday will be proportional to the amount of new snow that we receive overnight and during the day Wednesday.  If we wake up to a few inches of new snow, avalanches large enough to bury or injure a rider will be unlikely.  By late in the day, if we have gotten at 6-8 inches, then avalanches could be large on slopes that the wind has blown the new snow onto.  Lower in the terrain, the size of avalanches will correspond directly to the amount of new snow, and avalanches would only bury or injure a rider when terrain traps are present.  The forecast avalanche danger reflects the anticipated hazard late in the day.

Avalanche problems

  • Wind Slabs

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

    On Tuesday I observed blowing snow at alpine elevations but didn't see much snow moving near treeline where I was touring.  New snow will be accompanied by Light winds and Moderate gusts, which could load start zones immediately downwind of ridgelines or other features that block the wind.  Much of our surface snow is weak and could provide a weak layer over which these Wind Slabs are built.  If you choose to tour in wind affected terrain, utilize low angle or smaller slopes to evaluate the extent and stability of Wind Slabs.  Similarly, lower accumulations of new snow in the morning may provide a window into how reactive and large Wind Slabs could be by the end of the day.

  • Storm Slabs

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

    Even the high-end forecast storm totals of 10 inches don't often merit the inclusion of a Storm Slab problem, because avalanches large enough to bury or injure a rider would typically be unlikely.  I've chosen to include the Storm Slab problem for Wednesday (really Wednesday afternoon) given the weak nature of the previous surface snow, and the warming temperatures during Wednesday.  Storm Slab avalanches will be possible and could injure a rider where terrain traps are present.  Be mindful of terrain features like gullies, tight trees, or cliffs that could accentuate the consequences of a small avalanche.

Avalanche Discussion

Snow profiles and observations from Tuesday reveal a predominantly "right-side-up" snowpack.  The surface snow that I observed didn't facet quite as much as I thought it might on Monday night, but I could still see small faceted crystals under magnification.  This old snow surface could provide a weak layer for avalanches on Wednesday.  Sometimes it can be hard to tell what the failure plane is in new snow avalanches, but often we see avalanches propagating a bit further and being a bit more reactive under similar circumstances.

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