Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Shifting winds continue to build slabs, which will be largest and most reactive above treeline. Continue to avoid steep avalanche start zones and large open or unsupported terrain features on the lee sides of ridgelines. In sheltered terrain, sluffs will continue to chase you, so don't let them misdirect you into a terrain trap.

Avalanche problems

  • Wind Slabs

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

    Wind slabs were building on Friday, becoming more reactive during the afternoon, above a firmer layer of snow formed by extreme winds on Thursday. Moderate and shifting winds may continue to build these slabs or shift slabs into new locations or even the opposite sides of ridgelines. Slabs will be largest and most widespread above treeline, but could be large in heavily wind-exposed avalanche start zones near treeline as well. These slabs can be identified by active wind transport, recent cornice formation (which may include both sides of a ridgeline), and punchy snow layers. Continue to avoid wind-loaded slopes steeper than 35 degrees. Be aware that you can trigger slabs well below ridgeline, particularly in unsupported terrain. Below treeline, you might find isolated wind pillows, but wind slabs are not expected to remain a problem except in extreme terrain features. 

    Example: Wind loading in both directions forming cornices with potentially reactive slabs on the slopes below.

    Photo: Sam Siemens-Luthy

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Small dry loose avalanches were moving quickly in steep, wind-protected terrain on Thursday and Friday. Expect surface snow to destabilize and move with you in terrain approaching 40 degrees or steeper. These avalanches warrant greater caution above cliffs, depressions in the terrain, or rocks.

     

    An example of small dry loose sloughs .

    Photo: Katie Warren

Avalanche Discussion

Stormy weather continues to limit observations at upper elevations where winds decreased into the moderate range after an extreme wind event on Thursday. These winds impacting riding conditions in all but the most wind sheltered locations. Some minimal solar radiation on Thursday seemed to form a firmer crust-like layer that limits ski penetration below around 5000 ft. NWAC forecasters continued to get clean shears about 3-4" down running on on the new/old snow 3/2 interface (see photo gallery) on Gunsight Ridge. About 10" of snow has fallen atop this interface near Mt. Hood Meadows, which would produce a D1-1.5 avalanche if triggered. It's worth some hand shears or a quick pit to observe this interface before committing to larger steep open slopes. 

On Wednesday,  surface conditions were quite variable with NW winds drifting snow in the alpine,  rollerballs observed on steep sunny slopes, and dry snow and good snow conditions on cooler slopes at lower elevations.  Forecaster Joe Dellaporta found widespread surface hoar sparkling on the snow surface in these sheltered areas.  We're not yet sure whether this survived in any open slopes, but we remain slightly concerned that patches could have been preserved in isolated areas below treeline. If you're below treeline and experience shooting cracks or whumphs, dial back your terrain selection to exclude open slopes steeper than 30 degrees.

 

As the snow keeps piling up, keep SIS safety in mind: keep your partners in close sight and give tree-wells a wider buffer than normal.

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