Lawinenlagebericht

Mt Hood

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
Open full map
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Kernpunkte

Sunday will be sunny and unseasonably warm on Mt Hood. Any warm-up involving cold snow introduces uncertainty into the forecast. If you find evidence of surface crusts breaking down or wet or sticky snow in wind-sheltered areas, plan to stick to simple or lower-angle terrain.

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1

    In areas holding soft, dry snow, we're uncertain how prevalent the avalanches will be. Wet, loose avalanches may be isolated at elevations and aspects where the snow surfaces don't warm sufficiently. You can easily manage this uncertainty by looking for signs of instability; watch for fresh avalanches, rollerballs, and moist snow surfaces that slide easily. Direct sunshine on SW-S-SE aspects should be your primary concern at middle elevations, but warming may start to impact E and W aspects at lower elevations. 

    You're likely to find that winds over the last week have redistributed snow in exposed areas, while multiple days of sunshine have already created crusts on some sun-exposed aspects. The distribution of wind-affected snow may limit the impacts of warming to lower elevations.  Around 3-4" of snow generally defines the entrainment potential of a wet loose avalanche.  They could still ruin your day on a long, steep slope (and that slope may be above you), but more likely they will present a problem in a terrain trap such as above a creek or gulley. It is unlikely that the warm temperatures will impact middle and upper-elevation shaded aspects.

     

    Example: Rollerballs or 6" of wet slushy snow both point to the potential for wet loose avalanche activity.

    Photo: Joe Dellaporta

Avalanche Discussion

If you head into upper-elevation terrain or beyond, don't forget about the winds this past week. Most recently, some snow may have been transported by moderate winds Friday night. While the winds have calmed down, recent shallow slabs could linger on shaded aspects at the highest elevations. Take the time to evaluate the potential for slab formation by making use of small wind-loaded test slopes and by evaluating how easily the snow releases off the underlying crust. Tuesday's wind slabs remain featured for reference in the gallery but are unlikely to be reactive moving forward.

Early-season cornice failures could also trigger wind slabs on the slopes below, and represent a hazard in their own right. An example from Mt Rainier is in the gallery.

The battle between weak late November solar radiation and mild temperatures on one side versus cold snow will ensue this week. In general, we think the Mt Hood snowpack has the strength to handle the warming gracefully. It has seen plenty of consolidation through winds, sunshine, and mild temperatures. But it will experience even warmer temperatures along with more sunshine. Therefore, it's a good time to re-evaluate your plans when you see fresh avalanche activity or surface snow prone to sliding.

Temperatures rose into the upper 30s at Mt Hood Meadows upper station on Thursday, remained above freezing through Friday, and climbed into the mid-40s on Saturday.  Sunday might be even warmer. We still expect good overnight refreezes on SW-S-SE aspects, so on sun-exposed aspects, the breaking down is a good indicator of rising danger. You might also find that at lower elevations and in some valleys, cold temperatures linger far longer than at higher elevations and in these areas you might still find soft snow.

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

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