Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You can still trigger large and surprising avalanches in the Wenatchee Mountains. Recent strong winds will have formed deeper slabs below higher ridgelines in all parts of the zone.  Leave a wide buffer between you and wind-loaded slopes at mid and upper elevations.  

Problemi valanghivi

  • Persistent Slabs

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

    Persistent slab avalanches are dangerous and difficult to predict. They can propagate widely across terrain features and can result in large and deadly avalanches.  As we transition out of this period of High avalanche danger, continue to put a healthy buffer between where you travel and large open slopes steeper than 30 degrees.  Stay alert to signs of instability such as recent avalanches, shooting cracks, and whumphing collapses. 

    Large persistent slab avalanches are most likely in the Wenatchee mountains where snowpack tests and recent human triggered avalanches continue to indicate you can trigger a 1-2' slab avalanche above the prominent mid-January crust.  In other parts of the zone,  the likelihood of triggering a persistent slab avalanche in similar wind-loaded terrain may have increased after several days of rising temperatures, incremental loading, and moderate ridgeline winds.  Persistent slab avalanches may fail on other weak snow layers in the upper snowpack.  When the snowpack is complex, keep your terrain choices simple.  

    (1/28/2021) A skier intentionally triggered this avalanche (D2) in Icicle Creek on a north aspect at 3800ft that entrained soft snow and ran several hundred feet. The avalanche likely ran on the most recent (1/14) crust and associated weak snow (facets or surface hoar).

Avalanche Discussion

In the Mission Ridge area, 10 inches of new snow accumulated at upper elevations over the last 2 days with strong S-SW ridgeline winds throughout the period.  Less snowfall was received further west and closer to the Cascade Passes.  Rain reached up to at least 5000' in the East Central zone on Monday.  As the surface snow begins to refreeze later Monday night and during the day Tuesday, this should help strengthen the lower snowpack and reduce the avalanche hazard below treeline. 

Since the middle of last week, observers have reported triggering avalanches in the recent snow and widespread collapsing in the Icicle drainage, mountains near Leavenworth, and the Wenatchee Mountains. Observations show a variety of slopes to be prone to the problem. In the top 2-3 feet of the snowpack, there are a number of weak layers that could all result in an avalanche. These including surface hoar and facets resting on a crust beneath the snow that has fallen since the 24th, as well as more deeply buried facets sandwiched between weak crusts. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources. Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regioni coperte