Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

You may encounter small slabs you can easily trigger. Identify and steer around these by looking for wind-textured and cracking snow surface. Areas with 2 ft or more of snow above the recent rain crust remain at risk for sizeable avalanches that you might trigger with a cornice fall or on a steep, unsupported slope. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    Older, larger wind slabs hold our attention on Friday even though the slabs will be 2 days or older and stubborn to trigger. Although there were no reported human or explosive-triggered avalanches on Thursday, Mt. Hood Meadows Pro patrol reported numerous explosive-triggered wind slabs on N-E slopes between 6000-7000 ft on Wednesday. Some of these were large or even very large.  While these may be healing with time, they continue to warrant extra caution. You might expect around 2 ft of snow on average above the 3/12 crust at 6500-7000 ft. and 3-4" of snow above the 3/15 crust below around 6000 ft formed by a warm-up Monday night. A layer of colder, lower density snow sits above the 3/12 crust and should continue to be the culprit the largest avalanches triggered at upper elevations until it has time to settle.  If you find these layers buried deeper, you're on a wind-loaded slope. Much shallower wind slabs may sit on a thin temperature crust buried 3/17 as 1-2 inches of snowfall Thursday night get redistributed by moderate winds. These will be consequential primarily above terrain traps such as rocks and cliffs. Given the potentially deep avalanches, steer around potentially wind-loaded and unsupported start zones 35 degrees and steeper. Evaluate the potential of the slab to fail on or above the uppermost crust before engaging with larger terrain features.

    (3/16/2022)

    Wind Slab on NE aspect above treeline at Mt. Hood Meadows. Crown was 5 ft (skier for scale) with failure on a density change just above the 3/12 crust. Estimated D2.5.

    Photo: MHM Pro Patrol

Avalanche Discussion

After a period of active weather, the avalanche danger is gradually subsiding. However, given the size of slabs (up to 5 ft depth), we recommend a more cautious approach to near and above treeline terrain than you typically employ on a Moderate danger day.

An atmospheric river brought a period of mild temperatures and fluctuating freezing levels that extended through Monday night. Cooling temperatures arrived with around 7" of additional snowfall Tuesday through early Wednesday morning. Moderate WSW continued to load lee slopes. Since Monday, storm totals are around 20".  

Mt. Hood Pro Patrol reported easily triggered wind slabs 4-8" deep, running on the 3/15 crust on Tuesday. Earlier in the storm cycle, human-triggered wind slabs and storm slabs 6-12in deep were reported near and below treeline on Saturday and Sunday. All recent avalanche activity has failed at or above the old/new snow interface buried 3/12, and we do not expect avalanches to break deeper in the snowpack on old snow layers moving forward. 

Rollerball activity was also reported on Wednesday. Milder temperatures will battle it out with increasing winds to destabilize the surface snow. Shallow wet loose avalanches running within the 3-4" of snow above the 3/15 crust could develop if winds are light and the sun affects slopes in your area. If you sink into wet or sticky snow past your ankle, adjust your aspect and reduce your exposure to terrain traps.

 

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