Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Another warm day may set the stage for small wet avalanches along steep sunny, south facing terrain. Exposed alpine terrain and slopes adjacent to ridgelines above 6000 ft may still harbor thin slabs of wind drifted snow. While less likely, triggering an avalanche on open slopes that fails 1-2’ deep remains a concerning possibility, especially around Ahtanum Meadows. 

Problemi valanghivi

  • Loose Wet

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

    While most wet snow avalanches have likely run their main course, another round of clear skies and warm temperatures may reinvigorate some rollerballs or even some small wet loose avalanches on select sunny slopes. Most will be small, but don’t underestimate wet snow in bigger south facing terrain. Look for signs of warming and remember that rollerballs & pinwheels are often precursors to larger wet avalanches.

    (1/7/2025)

    Wet loose sluffs in the Stevens Pass zone. These naturals ran from steep, rocky outcroppings in East Highlands Bowl. E, 5500ft. These occurred 1-2 days ago. 

    Photo: Irene Henninger

  • Persistent Slabs

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

    Surface hoar buried 1-2’ below the surface is showing less signs of reactivity due to minimal weather inputs around the zone. That being said, if you dig down you’ll still encounter this problem across many slopes above 6000 ft. This layer is often identifiable as a thin gray line in the upper snowpack. Snowpack tests should help highlight this notorious weak layer. 

    This problem will be most concerning in areas with a cohesive slab resting over the weak layer. You’re most likely to find this dangerous set-up in areas that received more new snow ( from last week) like Ahtanum Meadows or adjacent to ridgelines where the wind has drifted snow into stiffer slabs. 

    These persistent slabs can break in surprising ways across terrain features. You may or may not see any signs of instability before triggering an avalanche. Stepping out blindly into steeper, more consequential terrain ups your chances for a dangerous surprise. Testing for the buried weak layers can reduce your risk if you don't get any red flags.You can also simply avoid open slopes greater than 30 degrees.

    (12/8/2024)

    You can reduce your exposure to this problem by staying off of an out from slopes that appear wind-drifted, but also sheltered enough to harbor a fragile weak layer like surface hoar. 

    Photo: Andy Harrington

Avalanche Discussion

NWAC forecasters traveled to Ahtanum Meadows on Tuesday to track our persistent slab probelm. They found this concerning weak layer of buried surface hoar in most places they dug, but it produced inconsistent test results. This was mainly due to the inconsistency of the overlying slab. In some places, this slab could be found and in other spots it lacked which would produce unremarkable test results. They also reported a couple of small D1 human-triggered avalanches in the Super Bowl (6800, NE) that failed roughly 12 inches in depth in wind drifted snow. Check out her full observation here. 

These recent observations highlight the variability of this weak layer. The best strategy during this time is to dig around on many aspects and look for unstable test results. Be sure there is no surface hoar before high-marking or traveling on steep, convex slopes over 30 degrees. 

While most of the activity was reported around Ahtanum Meadows above 6000 ft, don’t write it off elsewhere. Another skier-triggered avalanche failing at similar depths was also reported around the White Pass area on the same day ( Jan 3rd). 

If you get out, let us know what you see by submitting a public observation. 

Regioni coperte