Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Near and above treeline, old wind slabs are gaining strength but you can still trigger them on steep rollovers. Graupel on the snow surface may make visual identification difficult, so move to lower-angle slopes if you find firm-over-weak layering within the snowpack. Expect small wet avalanches on steep sun-affected avalanches if the winds die down.

Avalanche problems

  • Wind Slabs

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

    Tuesday's storm ended cold and convective with a lot of graupel, creating the potential for loose snow to run on steep slopes. However, the last storm was accompanied by plenty of wind and slabs lurk a few inches below the snow surface. While most of the slabs triggered by Mt Hood Meadows on Wednesday were stubborn and small, several were in the large range above the treeline. This size distribution should be the same on Thursday. Note any cracking under the less cohesive surface layer. Probe for punchy layers in the recent storm snow. And anticipate slab development on typical aspects even if you can't see them. When in doubt, stick to windward slopes, ridgelines, and avoid unsupported, lee slopes steeper than 35 degrees. If you are in an area with active wind transport or fresh, sharp cornices anticipate smaller, but more reactive slabs to develop in the immediate lee of ridgelines.

     

    Example: Steep, wind-loaded features where you can trigger an avalanche on Thursday.

    Photo: Paris Gore

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Temperatures will rise into the upper 30s or even low 40s on Thursday with clouds giving way to sunshine as the day progresses. Winds will be the primary thing keeping the snow surfaces cool, but if these die down for even a few minutes, expect rollerballs and a transition to small wet loose avalanches. Navigate away from steep slopes receiving sunshine, especially if the slopes are above you. We don't expect these will entrain the full 9-12" storm snow, but if you see large avalanches occurring, this problem is more serious than forecast and you should give a wide birth to all steep, open slopes on SW-S-SE aspects.

    Example: Rollerballs and pinwheels are an indicator of the snow surface becoming moist. 

    Photo: Andy Harrington

Avalanche Discussion

A storm cycle started Friday 2/3, which brought 2-3 ft of snow to Mt. Hood and has increased the snowpack depth by approximately 1.5 ft. Timberline now has more than 100 inches of snow on the ground. Strong W redistributed the recent 10" of storm snow that fell right-side-up Tuesday and Tuesday night, ending with graupel. Wednesday featured temperatures in the 20s, mostly cloudy skies, a few snow showers, and light winds. The favorable weather has helped stability. You might expect to find the 1/27 crust (the first major widely distrubted crust you will encounter) around 2-2.5 ft below the snow surface. Depths to this crust will be significantly more on more wind-loaded aspects on the E and N sides of the compass. Very thin melt-freeze crusts may be present on steep S-facing slopes above the 1/27 crust near and below treeline. In most areas, a thicker MLK crust lies around 3 ft down in the snowpack. In shallow snowpack areas such as Tilly Jane it may be only 1-2 ft down. In these shallower snowpack areas, you may find weakening within and around the MLK crust although we find it very unlikely that you would trigger an avalanche involving this layer several days after a loading event.

Although the recent avalanche activity has been smaller in size, it's worth noting that we're coming into a brief break from an active storm and avalanche cycle. The photo gallery shows a variety of stubborn, large (to D2.5) avalanches triggered using heavy artillery in the A-zone at Mt. Hood Meadows early Monday.

 

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