Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

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

Fresh or older wind drifts will be most reactive where temperatures remained colder - above treeline and on shaded slopes. Steer around small drifts on typical aspects or stiff slabs on atypical W or S aspects that could still release on a steep, unsupported rollover.

Avalanche problems

  • Wind Slabs

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

    Expect slabs to be more reactive and consequential once you rise above the freezing line on Wednesday.

    Older slabs will be most consequential, but significantly harder to trigger. These slabs formed by extreme NE over the weekend and will be 3-4 days old by Wednesday. A major NE wind event blew low-density snow into thick drifts. Our neighbor volcano, Mt St Helens produced a natural D2 avalanche (likely Sunday) and a human-triggered D2 avalanche (Monday). Both avalanches released on S or SW aspects near treeline, ran on crusts, and produced 1-3 ft crowns that were frequently low on the slope.  You can read the full report here. These avalanches are quite relevant for Mt. Hood given similar snow amounts above the 1/27 crust in both areas. In the Mt. Hood terrain, you'd be unlucky to trigger a large slab, but you can lower the odds even more by avoiding very steep, convex rollovers and consequential slopes on atypical W-SW-S aspects where these slabs have been most prevalent. Near treeline, we think that mild temperatures have rendered most of these slabs dormant, but keep them on your mind in case you find evidence to the contrary (cracking surfaces, firm or punchy layering, etc.).

    You are more likely to trigger a slab within freshly drifted snow as W and WSW winds continue to transport snow above 6500 ft. This snow will drift onto previously scoured surfaces including sastrugi or crusts. Expect these slabs to run efficiently on the crusts. You should be able to identify and steer around reactive pockets in actively drifting deposits and on slopes below small, sharp cornices. 

    (1/30/2023)

    A natural Wind Slab avalanche was observed on Mount St. Helens on 1/30. Note the convex slope and nearby rocky terrain. [HS-N-D2-R2-I SSW 4500’]

    Photo: NWAC Forecasters

Avalanche Discussion

Mild, above-freezing temperatures moved into lower and mid elevations on Mt. Hood Monday night and remained on Tuesday. We're expecting the freezing level to rise into above treeline terrain by Tuesday afternoon. You could trigger an isolated wet loose avalanche if daytime heating breaks down surface crusts on very steep and wind-sheltered SW-S-SE aspects. More significantly, the temperatures are accelerating the healing of wind slabs, particularly below and near treeline.

Reports have indicated firm surfaces and difficult travel conditions abound. Some observers have described conditions that are easier on the ascent than the descent. 

Most exposed aspects are either exposed to crusts, sastrugi, or wind slabs. Many of these surfaces may develop a thin crust by Wednesday or you may find moistening, softening snow if the winds relent. Saturday's highly redistributed 3" snow event sits on old wind-affected snow layers or a thin, breakable melt-freeze crust (1/28) that may be present on sun-affected aspects near treeline. Below that, you'll find a firmer and widespread 1/27 crust which now has a consolidating 3-6" of snow (on average) above it. The MLK crust sits around 2 ft below the snow surface and was the culprit for at least one recent avalanche on Mt. St. Helens. The crust is around 2" thick and partially decomposing with weakening/faceting snow just below it on Mt. Hood. We don't currently know whether this crust may be a layer of concern at upper elevations on Mt. Hood.

If you get out into the new snow, let us know what you see by submitting a public observation!

 

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