Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Heavy snow, strong, winds and rising snow levels will create dangerous avalanches. You can easily trigger them on steep slopes greater than 35 degrees. Isolated natural avalanches might also descend from heavily wind-loaded upper-elevation slopes. Stick to simple terrain and reduce your overhead exposure.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2.5

    We're expecting 10-20" of snow to fall in wind-loaded terrain above the 4500 ft rain/snow line. The new snow lies above 10-15" of recent snow that hasn't had time to settle. All this new snow needs time to heal. These slabs could grow large in sheltered terrain by entraining low-density recent snow. In wind-loaded terrain, these slabs could grow to D2.5 or possibly larger on the upper mountain. These slabs would likely involve snow down to the 3/18 sun crust (around 2-3 ft down by Friday). With clear and present danger, avoiding exposure to large open slopes steeper than 35 degrees or terrain connected to upper-elevation start zones is best. Instead choose lower angle simple terrain or seek trees. Shooting cracks and easily triggered test slopes confirm the problem.

    Example: A larger crown similar to what you might trigger in wind-loaded terrain on Saturday. 

    Photo: MHM Pro Patrol

Avalanche Discussion

Friday is likely the most reactive day of the week in the mountains thanks to a strong storm system unloading on Mt Hood. 

On Thursday, Mt Hood Meadows Patrol reported 10-12" of snow above the 12/18 sun crust. They triggered a handful of small storm slabs in control, picking up 6-10" Wednesday night reported on their upper chairlifts, with another 4-5" arriving on Thursday. Patrol triggered two large hard slabs (snowcat and explosive triggers) with crowns up to 4 ft deep on S aspects at 7200 ft on Wednesday.

An observer headed up the Palmer Snowfield on Wednesday was able to trigger stubborn slabs 8-12" thick. A crust 2-3 ft down had a clean shear in snowpack tests. By now, Friday this layer might be 4-5 ft down and there's an outside chance that intense wind loading or a cornice fall could trigger something very large on this layer. A rider triggered a size D1.5 cornice fall in White River on Wednesday, which entrained some dry snow, but the rider rode out unscathed. Such cornice falls should remain on your mind both along ridges and near the edges of escarpments, particularly late in the season when cornices are at peak size and actively building during a storm cycle.

The snowpack is layered, wind-affected, and it's difficult to keep up with the interfaces, crusts, and dynamic slab properties at middle and upper elevations during relatively brief weather windows. All that is to say, it's worth dialing it back and taking the travel advice seriously in times like this. 

You can help us gather more data by submitting an observation HERE or via the Avy App.

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