Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

We're in the midst of a winter storm maintaining dangerous avalanche conditions in the Mt Hood zone. Continue to seek out more sheltered slopes out of the wind that are less than 35 degrees. The snow is deep, so have communication devices and keep partners in close sight. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    Very strong west winds, along with several feet of new snow, have created thick, dense slabs on leeward features across the zone. These slabs will absolutely be large enough to bury and kill you on Tuesday. These avalanches could break several feet deep and wrap around terrain features. 

    You won't need a big wind-loaded feature to create a problem. This will be the day to steer clear of leeward start zones like Salmon River Canyon, White River, and other ridges and moraines around Mt Hood.

    Use visual clues like blowing snow, cornice formation, and textured drifts to help you identify these dangerous areas. Shooting cracks or whumphing collapses are apparent signs that you found an unstable slab. Continue giving small and large wind-loaded slopes a wide berth until this storm settles. 

    (2/27/2023)

    Pay attention to blowing snow and sharp cornices to help you spot what slopes are loading up. 

    Photo: Andy Harrington

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    New snow is rapidly stacking up. Even though this snow has fallen on a cooling trend, avalanche professionals and observers continue to report reactive storm snow and small storm slabs failing in sheltered, steep terrain. You'll typically find the most reactive (and dangerous) conditions during periods of heavy snowfall. As you travel, consider any steep slope as suspect. Look for signs of instability such as cracking in the new snow, test slopes releasing easily, or notice hard-over-soft layering. Default to less steep terrain during periods of heavy snowfall or if you notice any of the above signs of instability. 

    Loose snow avalanches: 

    We have a lot of low-density, cohesionless snow. Observers reported dry loose running far and fast, so expect these to continue on Tuesday. If skies are sunnier than weather models predict, we may see some surficial sun-induced loose snow avalanches. Most avalanches should be relatively small, but some could be large enough to knock you over and carry you where you don't want to go. 

    (2/16/2024)

    An example of a storm slab in sheltered terrain below treeline. 

    Photo: Mt Hood Meadows Pro Patrol

Avalanche Discussion

Wow! What a storm. As I write this, weather stations across the Mt Hood zone have picked up 25-30 inches of new snow (and counting). This snow came in on a cooling trend, so backcountry travelers reported 'blower' and 'deep' riding conditions. Once above 5500 ft, strong west winds moved large amounts of snow, making for stormy conditions on Tuesday. The Mt Hood Meadows Pro Patrol reported triggering numerous small storm slabs and dry loose in their more sheltered terrain. Our friends at the USGS also reported a couple of seismic-observed D3s in heavily loaded alpine terrain in the White River Canyon and the Eliot Glacier Headwall.

The storm is far from over. Expect another 1-2 ft of new snow by 6 pm on Tuesday. Another significant and potent system will arrive Tuesday night into Wednesday. This system will feature warmer and wetter conditions which will undoubtedly spike avalanche danger come Wednesday. 

Deeper layers of concern, such as the Early February crust, continue to produce inconsistent snowpack test results across the zone. We generally find this layer rounding and gaining strength in the places we've traveled. However, we're discovering it's also very spatially variable. In some areas, such as the northern aspects above 6000 ft, we continue to see weak snow producing propagation and untable test results. The big question now is how this potential weak layer will react to several feet of snow? We're unsure, but that's more reason to increase your margins as you travel in the coming days. 

You can add to the forecast! Submit your public observations here. 

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