Bollettino valanghe

East Slopes North

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

Update: Considerable Danger. Recent strong winds have formed fresh wind slabs near and above treeline.  Loose snow avalanches are possible on steep sunny slopes Wednesday.  In the eastern mountains, recent collapses and snowpack tests suggest you may trigger avalanches in older weak layers.  Consider traveling in lower angle terrain until you can evaluate the snowpack in this area. 

Problemi valanghivi

  • Loose Wet

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

    With sunshine expected Wednesday, loose snow avalanches will likely release from steep sunny slopes.   These point releases may be of the dry or wet variety depending on the time of day and elevation.  Don't let them catch you off guard around terrain traps that would amplify the consequences of a small avalanche.  If you start to see pinwheels or rollerballs, or snow shedding below rock bands, consider moving to shadier aspects or to slightly lower angle terrain. 

    Example of small wet loose avalanches you may see on steep sunny slopes.

  • Wind Slabs

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

    Strong SW winds continued to transport new and recent snowfall onto lee slopes near and above treeline Tuesday.   Feel for wind stiffened or hollow sounding snow as you climb in elevation and change aspects.  Watch for shooting cracks as a clear sign of instability.  Use caution on wind loaded slopes steeper than 35 degrees and steer around typical trigger points like convex rollovers and unsupported slopes.  Larger avalanches are possible if new wind slabs step down to weak snow layers around 1.5 ft below the surface. 

    (1/31/2021) Cracks and a small chunk of a slab triggered in a drift on a leeward SE aspect near treeline just east of Washington Pass. Photo: Josh Hirshberg

Avalanche Discussion

On Tuesday, observers reported about 1.5' of snow above the Jan 30th interface in the Washington Pass area following several days of light snowfall and moderate SW ridgeline winds.  On Sunday in the Cutthroat drainage, professionals checked out a layer of small rounding facets over a crust that was buried on the 24th. On a southeast aspect around 5,700ft, they found the facets 54cm (about 2ft) below the surface.  At upper elevations near and just east of Washington Pass, the mid and lower snowpack is deep and strong.

On Monday, observers in the Twisp drainage experienced collapses at 4800'. Snowpack tests showed the potential for propagation 1.5 feet down on the Jan 24th weak snow (facets) layer at 5700'.  Also on Monday, a large avalanche was heard in the Lost River drainage following a period of warming and light to moderate precipitation. This ties into an observation in the eastern mountains from last Wednesday reporting cracking and collapsing on older facets in snow from early January.  To sum it up, we have higher uncertainty with a shallower and weaker snowpack in the eastern part of the zone. If you travel to areas such as the Chelan-Sawtooth Mountains, Twisp River, and Chewuch drainages, take time to dig in the snow and look for older weak layers. Consider traveling in lower angle terrain and smaller terrain features.  We don't have any confirmed reports of persistent slab avalanches, but you'll need to evaluate the upper snowpack carefully before committing to more consequential terrain.   

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