Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

New snow, drifting wind speeds, and increasing freezing levels will create overlapping avalanche problems on Monday. You’ll find the most dangerous avalanche conditions in wind-loaded terrain, but don’t ignore more sheltered steep slopes that hold over 6 inches of new snow. Pay attention to signs of warming as the day progresses and don’t ignore obvious signs of instability like cracking, new snow sliding easily, or recent avalanche activity. 

Problemi valanghivi

  • Wind Slabs

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

    New snow will accompany moderate to strong SW winds, so be on the lookout for reactive wind slabs as you climb into exposed terrain across the zone. These slabs will likely stay reactive throughout the day, but they may be most primed for human triggering during the morning hours, which corresponds with the tail-end of the heavy precipitation. Expect these slabs to be larger and more widespread above 6000 ft or in western parts of the zone that receive more new snow. 

    Use visual clues like blowing snow and textured surfaces to help you pinpoint where the wind has been at work. You’ll typically find these slabs on the leeside of ridges, below cornices, or on the beak-over of steep slopes. You can use small test slopes or hand pits to gauge how reactive these slabs are. Cracks shooting out from under your feet or machine are obvious signs that you may have found an unstable wind slab.

    Additional Discussion: You may be able to trigger small storm slabs in areas that receive over 6 inches of new snow.  Pay attention to hard-over-soft laying and use small test slopes to gauge how reactive this new snow is before stepping into steeper terrain. 

    (12/31/2023)

    Simplify your terrain selection if you notice signs like this. 

    Photo: Joe Dellaporta

  • Loose Wet

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

    Clearing skies and increasing freezing levels will promote a round of small wet loose avalanches involving the recent snow. These won’t be big, but don't be caught off guard in consequential terrain. Expect this wet loose activity to be most prevalent on solar slopes and near rocky, craggy terrain. Look for rollerballs and sticky snow surfaces precursors to larger wet loose avalanches.

    (12/10/2024)

    Rollerballs often preceed wet loose avalanches.

    Photo: Irene Henninger

Avalanche Discussion

This forecast period features fluctuating freezing levels, so be on the lookout for overlapping avalanche problems on Monday. You’ll generally find the most dangerous conditions at upper elevations, but don’t underestimate the middle elevations in areas that received more than 6 inches of new snow. These elevations will be the most impacted by warming and could be the most susceptible to wet loose avalanche activity, and even some storm slab activity at the western end of the zone that receives more new snow. The bottom line is simple on days like this; be flexible with your plans and adjust your terrain to match the conditions you find. 

The 12/7 crust likely won’t be an issue in most middle and lower elevations moving forward. Backcountry travelers continue to find rough travel at these elevations. However, higher elevations that escaped the recent rain event may still harbor weak snow adjacent to this crust. The Mission Ridge Pro Patrol reported propagating test results on faceted grains just beneath the 12/7 crust  on Saturday (NE, 6400 ft). While this is only one data point in the zone, it's worth keeping on your radar if you venture to higher-elevation terrain. 

Let us know what you see by submitting a public observation. 

 

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