Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Snow level fluctuations make it difficult to predict the avalanche problem type, but we are confident that very dangerous avalanche conditions will continue at upper elevations. Stay off of and out from under-saturated or wind-loaded slopes and anything connected to upper-elevation start zones. In areas where firm surface crusts form, the danger should be lower than forecast.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–3

    We're combining wind and storm slabs into a single problem. As snow builds above the 12/27 crust, it may become easy to trigger if fluctuating temperatures or high snowfall rates convert that snow into a slab.  All it takes is 8" of snow to trigger a storm slab on a steep or poorly supported slope. Keep it simple and stick to slopes less than 35 degrees unless you find a firm, supportable crust near the snow surface to limit the size of potential storm and wind slabs. 

    Wind-loaded slopes will produce the largest avalanches and the most instability, defining the maximum size potential for this problem. Above 6600 ft, we don't know whether the 12/27 crust exists. At these elevations, start zones have been loading since Christmas and the next 24-hours will be consistently in the highly productive range for wind loading on Mt Hood. Avoid all upper elevation and connected terrain including the bottoms these long slide paths frequently converge. Winds will also build shallower slabs 1-3 ft thick at middle and potentially into exposed lower-elevation terrain where the advice of avoiding wind-loaded terrain should be taken seriously.

  • Loose Wet

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

    Rain, freezing rain, sleet? We're not sure exactly what precipitation type will fall over the next 24 hours in the wake of a poorly predicted rain event on Friday. Although Friday's heavy rainfall has mitigated some of the hazard, saturated snow surfaces remain. You could trigger this unstable snow to form avalanches that might entrain recent snow. They could alternatively fail naturally on a steep or unsupported slope. Take the time to evaluate the upper snowpack. If you find at least a few inches of manky, saturated snow, dial it back and choose mellow terrain until the mank begins to refreeze.

    Example: A natural size 2 wet loose avalanche.

    Photo: Mt Hood Meadows Patrol

Avalanche Discussion

The firehose has been aimed squarely at Mt Hood since Christmas. Back-to-back storm systems have brought 40" of snow before snow changed to a mix of freezing rain and rain up to at least 6600 ft around 7 AM on Friday while winds continued to rip in the moderate to strong range. Above these elevations, we haven't had reports since prior to the storm cycle and the unrelenting storm hasn't provided any visibility. At these elevations, the next crust should be the Solstice Crust which was formed following the rain event that produced the very large avalanche cycle pictured in the gallery. The Christmas Boxing day storm that started the storm cycle also brought sustained in the 40-50 mph range with gusts over 100 mph that knocked down medium-sized heavily rimed trees 25" in diameter.  

Mt Hood Meadows Pro Patrol reported periods of highly reactive snow early Thursday, and even more reactive snow during the snow-to-rain transition on Friday. Powder cloud avalanches transitioned to easily triggered wet avalanches entraining up to size 2. Photos 

The surface crust should set a new ground at middle and lower elevations once it refreezes, but we're not sure when that will occur. If we get a transition back to snow, Mt Hood can anticipate 8-10" of new snow by the end of the day and storm slabs would be the primary problem at these elevations. If above freezing layers in the atmosphere continue to produce rain and freezing, then the wet avalanche hazard should remain your primary concern.

There is good news on the horizon and cooler, less stormy weather should be arriving late in the weekend through early next week.

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