Bulletin d’avalanche

Mt Hood

Northwest Avalanche Center
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Danger d’avalanche

Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Wind slabs remain large, deep, and unusually far down on slopes in wind-exposed terrain. However, your odds of triggering a stubborn slab continue to decrease. Steer around high consequence or extreme terrain in addition to rollovers steeper than 35 degrees.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2.5

    An extreme NW wind event blasted 8" of snow into stiff and very thick slabs Saturday night. Control results with explosives at Mt Hood Meadows yielded three large avalanches on generally E-facing slopes with crowns up to 6-8 ft deep (images in the photo gallery). Slabs were triggered mid-way down or even low on the slope, a pattern typical of extreme NW wind events on Mt. Hood. The good news mild temperatures with minimal fresh wind transport has helped these slabs to gradually gain strength. Given the scale of these avalanches and the consequences of taking a ride, we still recommend steering clear of steep convexities in the terrain, particularly low down in an avalanche path where large pillow-like slabs lurk. At this point, you are most likely to trigger such a slab toward the edge where it is less thick in shallow, rocky terrain. When in doubt, you can travel safely on wind-scoured slopes (sastrugi), ridges, or slopes less than 35 degrees. While slabs may exist below treeline, we think the mild temperatures on Monday have hastened the healing process for these shallower instabilities, rendering them mostly unreactive.

    (1/22/2023)

    D2-2.5 (large) explosive triggered wind slabs in atypical alpine start zones low on the slope.

    Photo: Mt Hood Meadows Patrol

Avalanche Discussion

Late Sunday brought a report of a snowmobile triggered avalanche in the neighboring Cascades West South zone on Mt. St. Helens where the rider was caught and buried over 6’ deep. Rescuers were able to successfully extract the rider and no significant injuries were reported. More information is available here.

There's not much snow that hasn't been affected by the wind on Mt. Hood. In fact, there were periods of strong NW winds on Monday, but the minimal snow that was available and transported didn't really alter the picture. You can still find less wind-affected snow below 5500 ft and with some sunshine on Monday, these surfaces may have a crust by Tuesday morning. Periods of sunshine on Tuesday will probably break down the thin crusts and you can trigger a shallow wet loose avalanche below 5500 ft on a very steep SW-S-SE facing slope. These avalanches could be consequential where they push you into undesirable terrain features such as creeks, depressions, or other terrain traps.

Surface hoar was observed in some locations prior to Saturday's storm, however, the intensity of the winds with Saturday night's system likely destroyed any weak grains prior to burial.

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