Bulletin d’avalanche

Mt Hood

Northwest Avalanche Center
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Danger d’avalanche

Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Dangerous avalanche conditions will develop on Wednesday as a strong spring storm impacts the area.  Up high, assume you can trigger a large slab avalanche on steep wind-loaded slopes.  At lower elevations, avoid terrain where you could trigger a wet loose avalanche, especially near cliffs, creek holes, and other terrain traps.  

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    We're going to take the winds and snowfall up a notch late Tuesday night and Wednesday as a strong spring storm impacts the area.  Strong W-SW ridgeline winds and extreme alpine winds will load lee slopes with new and recent snowfall from the last 2 days.  Slabs are growing deeper over the 3/22 crust and natural avalanches may occur as the storm wears on.  This is not the day to thread the needle; don't travel on or below a large open slope above treeline with poor visibility and blowing snow.  

    Cracking in the new snow, blowing snow, sharp cornices, and wind-sculpted features are red flags that you should avoid nearby steep wind-loaded slopes at any elevation.  Ride out the storm by sticking to lower angle and sheltered terrain. 

    The storm will come in "upside down" with denser snow building over lighter snow.  Use caution around very steep unsupported slopes and convex rollovers even in wind-sheltered terrain to avoid triggering a storm slab avalanche. 

    (3/26/2024)

    You can use small test slopes like this to help you gauge the sensitivity of wind-drifted snow. 

    Cracking in denser wind-drifted snow.  Wind slabs averaged 6-12" deep Tuesday.  Slab will be deeper on some lee slopes Wednesday. 

    Photo: Joe Dellaporta

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    Rain should creep up to 5000-5500' on Wednesday, increasing the likelihood of wet loose avalanches.  Whether they are human triggered or natural, most wet loose avalanches will be small, but some may gouge down into recent snow becoming large and powerful in their own right.  The threat of rain on snow will expand the wet loose potential around the dial.  We have more recent snow available for large wet loose avalanches on certain parts of the mountain (south and west-side).   Wet loose avalanches may run further than you expect above 5000' where the snowfall from the last few days sits over a firm crust. 

    Wherever you find yourself punching into wet snow, observe rollerballs/pinwheels on steep slopes, or see natural wet loose avalanches, you know it's time to avoid very steep terrain.   Lower elevations are losing snow as we shift into spring and increasing the number of hazards you can pushed into or over.  Even a small wet loose avalanche above a terrain trap like cliffs, or a creek hole can have a serious outcome.  

     

    (2/18/2024)

    Even a small avalanche could have dire consequences in the wrong spot.  

    Note the slab avalanche on the left and the rollerballs indicating wet loose avalanche potential on the right above the open water. 

    Photo: Mt Hood Meadows Pro Patrol

Avalanche Discussion

Blowing snow formed fresh wind slab at middle and upper elevations on Tuesday.  Professionals generally found wind slabs were 6-12" deep and stubborn to trigger.  Small wet loose avalanches and rollerballs were observed at lower elevations.   The Timberline and west-side of the mountain has received more snow than the Meadows side of the mountain over the last 2 days.  In non-wind affected terrain, roughly 8" of snow could be found above the 3/22 crust on the SE side of the mountain.  That depth is likely 12"+ on the south and west side of the mountain.  Above 5000ft, the new and recent snow is building over a firm and slick crust (3/22).  This may make for an excellent bed surface for avalanches to run on as we enter a mid-week storm cycle.  

While the new snow will help improve travel, snow surfaces at lower elevations, forested terrain and steep south and west aspects are in rough shape following the warm-up.  Even with a few inches of new snow, be aware of late-season travel challenges and hazards.

You can contribute to the forecast! Submit an observation here. 

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