Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Continued precipitation and uncertainty around weak snow above a crust could result in dangerous avalanche conditions on Thursday. If you encounter red-flag signs of instability such as whumpfing collapses or shooting cracks, dial back your terrain choices and avoid slopes over 35 degrees. 

Problemi valanghivi

  • Storm Slabs

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

    On Thursday, be sure to take the time to look for heavy snow over weak snow or mid-storm instabilities before committing to terrain. The snowpack around the pass has been through a lot over the last few days due to fluctuating freezing levels and at times, heavy precipitation and wind. Some additional snow is on the way on Thursday and will only add another layer of complexity to the snowpack. You will find varying depths of new snow based on aspect, elevation, and exposure to wind, but your constant snowpack marker will be the Early March Crust. Be sure to take the time to dig down with your hand or shovel to this layer to investigate the snow above it and avoid slopes over 35 degrees wherever you find a poor bond or active interstorm layer.

    On upper elevation northerly facing slopes (NE-N-NW), dangerous avalanche conditions could exist and you need to take the extra time to look for the existence of the 3/8 facets above the Early March Crust. These avalanches could fail in surprising ways, spanning far distances or breaking above you. They could even be triggered remotely from below or on ridgelines. If you experience whumpfing collapses, they should immediately get your attention and steer you to lower angled terrain. See the discussion for more details.

    (3/15/2022)

    Compression tests highlighted a mid-storm density break and failures above the Early March Crust on 3/15. You can use hand pits and test slopes as you travel to get similar information about slab potential.

    Photo: Andy Harrington

Avalanche Discussion

On Wednesday, Alpental Pro Patrol reported triggering 6” slabs in the new snow with their control work within the ski area. As they moved toward their Back Bowls, they started to get 2 foot slabs breaking on NE facing convexities. As mentioned above, we are still concerned about the facets that are sitting above the Early March Crust but do not have confirmation of how they are reacting at Snoqualmie Pass at this time. Could this observation from Alpental be an indication that they are alive? In the neighboring West South zone, a similar snowpack set-up to what we had at Snoqualmie existed prior to the storm. On Wednesday skiers triggered multiple slab avalanches large enough to bury and kill you near White Pass and Crystal Mountain. Many of these slides were remotely triggered. You could travel on multiple aspects or dig around and not see this set-up. You are going to want to target upper elevation slopes that have a northerly tilt (NE-N-NW). You will likely need to get above the rain/snow line from this week’s storm.  Please help us out by letting us know what you find out there by submitting a public observation.

Elsewhere in the zone, professionals reported various snow conditions on Wednesday and wet avalanche activity as temperatures warmed in the springtime weather. This will be a persistent issue for us for much of the remainder of the season and we could probably forecast Wet Loose almost everyday. Thursday will be no different. As precipitation rolls in, fluctuating freezing levels could produce rain or heavy wet snow at mid to lower elevations. Keep wet avalanches on your radar anywhere you encounter wet and sticky snow.

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