Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

New snow, increasing wind speeds, and a possible weak layer will make for a dangerous day in the mountains. Steer around pockets of fresh wind drifted snow at mid and upper elevations. In more sheltered locations below treeline, be suspicious of any steep open slope. In these locations, you may be able to trigger large and surprising avalanches that break 1-2 ft deep.

Avalanche problems

  • Wind Slabs

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

    It's pretty simple… winds speeds are ramping up and we have plenty of low density snow available for transport. This combination will likely create reactive wind slabs near and above treeline. 

    East and west winds have been at work drifting new snow in the last 24 hours, so you may find these slabs all over the compass. As you move through the mountains look for blowing snow, fresh cornices, and pillow-like slabs at the snow surface to help you identify possible slopes of concern.  Blowing snow should be quite obvious on Thursday, so default to more sheltered slopes out of the wind zone to avoid this problem. 

    (1/17/2023)

    Shooting crack in wind drifted snow - a red flag that should not be ignored.  Avoid wind loaded slopes if you notice signs like this. 

    Photo: Joe Dellaporta

  • Storm Slabs

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

    On Wednesday observers reported a widely propagating natural avalanche that broke 1-2 feet deep and reactive storm snow during the afternoon hours. You may find similar conditions as new snow continues to  pile up Thursday, especially during heavier periods of precipitation. 

    We have limited information on the distribution of this weak layer responsible for this naturally occurring avalanche. What we do know is we had isolated pockets of surface hoar form in areas on the clear day on March 1. Following March 1st, winds kicked up and destroyed this surface hoar many exposed areas, but possibly not in others. So the distribution is the real question mark.

    Thursday will be a good day to dial it back. Pay attention to increasing snow intensities and dig down to look for a weak layer 1-2’ below the snow surface. Use snowpack test and visually look for a thin gray line in the upper snowpack before committing to steeper, open slopes at these elevations. 

     

    (3/8/2023)

    This natural avalanche occured Wednesday on a North aspect @ 5400 ft in the Bennet Pass area. Crown depths ranged from 1-2' deep. 

    Photo: Trevor Wright

Avalanche Discussion

Uncertainty describes this forecast well. On Wednesday we received a report of a surprising natural avalanche  that propagated widely (N aspect, 5400 ft) in the Bennet Pass area. The observer reported crown depths ranging from 1-2’ ft deep and characterized it as a D2. The grains involved with the failure  layer are unknown, but appear persistent-like and likely involving the 3/2 interface.  Earlier on Wednesday, an avalanche class in the Vista Ridge area also reported finding a couple notable layers of concern. They reported a layer of buried surface hoar that sits 12-15 inches below the snow surface which produced planar results with shovel tilt tests. 

This information from today tells us that we have a weak layer (possibly buried surface hoar) in isolated, sheltered areas. This is a good time to take a step back and let the storm run its course. Over the next 24 hours, Mt Hood is in for a wild ride with increasing wind speeds and heavy precipitation.  

If you get out into the mountains, let us know what you see by submitting a public observation. 

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