Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 8 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Heavy rain erased much of the low and mid-elevation snowpack. Don’t linger beneath rocky slopes or corniced ridges holding wet snow. Reaching trailheads will be challenging due to many washouts, landslides, and road closures.

Problemi valanghivi

  • Glide Cracks

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

    Depending on elevation and the extent of snow cover,  there is still a low chance of seeing glide, wet loose, and wet slab avalanches, cornice falls, or just blocks of snow shedding from rocks and cliffs. The main danger isn't so much triggering a wet avalanche on steep snow-covered slopes; it's that wet, saturated snowpacks tend to unload sporadically even after precipitation ends.

    Keep an eye on what is above you if you make it into the mountains on Friday, and don't linger under anything else that looks wet, sketchy, and poorly attached to the mountain. You might find new snow and fresh wet avalanches if you make it to upper elevations. Pay attention to new snow depths and wet new snow as you get higher.

     

    Example of a large glide avalanche on rock slab (just left of center) below Huntoon Point last winter.  Note hanging blocks, hangfire and a sagging cornice all surrounding avalanche release area.

Avalanche Discussion

Concern about avalanche danger seems a bit trivial compared to the damage to infrastructure and property throughout the Cascades. No direct observations of avalanche activity were reported. Difficult access and much bigger concerns kept nearly everyone out of the mountains on Thursday. It’s a safe bet that upper and some middle elevation areas experienced natural activity in the form of wet loose and other types of wet avalanches due to heavy rainfall. 

It's still a bit of a guess how much snow is left at mid elevations across the zone. The likelihood of seeing  a new avalanche is low due to the end of heavy precipitation, cooling temperatures, and the fact that much of what was there to shed has already done so.  But it's hard to call it low danger when there's an outside chance a ton or two of wet snow could peel off the mountain above you.

Despite the sheer volume of rain over the past 48 hours - anywhere from 5.5 to 10.0 inches, depending on what station you look at - there is evidence that some new snow fell at upper elevations as temperatures cooled.  Unfortunately, any dry snow up there won't last long, with periods of light precipitation and rising snow levels heading into the weekend. While more warming and a bit of rain shouldn't do much more damage at mid elevations, it could get a reaction from new snow at upper elevations.

With the warm start to the 25-26 winter season, we have less snowpack information than usual to start daily forecast operations. For zones and elevation bands with less snow than needed for avalanche hazard, we will issue a forecast with No Rating. Anticipated avalanche and weather conditions will still be updated daily. NWAC will issue an avalanche danger rating for a zone when enough snow to produce avalanches has accumulated at middle and upper elevations.

 

 

 

 

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