Bollettino valanghe

West Slopes South

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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In sintesi

Dangerous avalanche conditions will exist throughout the mountains of the West South on Tuesday. The snowpack has changed dramatically in a short period of time, so let it adjust to the recent load by sticking to gentle terrain less than 30 degrees. If you’re in the southern end of the zone, you may want to consider reading the Mt. Hood forecast and be prepared for High avalanche danger.

Problemi valanghivi

  • Storm Slabs

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

    A lot has changed since Sunday afternoon when a potent storm first took aim at the West South. Slab avalanches are now the primary concern and will be more likely on slopes over 30 degrees and in wind-loaded terrain. Digging with your hands or shovel to identify heavy snow over weak snow or areas of poor bonding will be necessary. Small test slopes can give you some information about how the recent storm snow is reacting to your weight. Be leery if the new snow forms a cohesive slab or if blocks of snow are failing in your tests. Any slabs should grow in size as you ascend in elevation, particularly in areas that are prone to wind. Slabs in wind-prone areas could be several feet deep and much firmer than the surrounding snow, possibly feeling hollow. Regardless of if the slab is composed of storm snow or thickened by the wind, you should avoid slopes over 30 degrees if you notice failures in your tests or see red flag signs of instability such as shooting cracks or whumpfing collapses. 

    There is still the possibility of surprising avalanches that wrap around terrain features or propagate widely, even in areas often considered as “safe”, such as treed areas. If you notice any avalanches acting in this way, you should dial back your terrain choices even more.

    (1/3/2022)

    Even on mellow terrain like this test slope, avalanches were easy to trigger in the nearby Snoqualmie Pass zone on Monday.

    Photo: Erik Olson

Avalanche Discussion

Observations were limited around the zone on Monday due to the ferocity of the storm. What we do know is that WSDOT’s avalanche crew reported multiple small natural avalanches at White Pass. Additionally, Crystal Mountain Pro Patrol reported widespread large (D2-D2.5) avalanches during their control work this morning. Our weather station network indicates that around two feet of new snow fell around the zone with significant winds, likely initiating a widespread natural avalanche cycle. 

As we head into Tuesday, the storm may be trending downward, but it is not over yet and we expect human-triggered avalanches to be widespread. Continued precipitation, windy conditions, and a warming trend should help to further develop slabs, even on slopes that have already slid. Danger could be elevated in the southern portion of the zone where more precipitation, stronger winds, and a larger warming trend are possible. Regardless of your location, natural avalanches are not out of the question and will be more likely during periods of high precipitation rates or strong winds. With the additional 2 feet of new snow on top of the ~3 feet of snow we previously had sitting on the Solstice Crust, the potential for large and dangerous avalanches is very real and you should manage terrain carefully. 

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