Bollettino valanghe

East Slopes South

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 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Warming temperatures and a weak snowpack structure are only increasing the likelihood of you triggering avalanches - and some could grow quite large. So keep your terrain selection simple by sticking to lower-angle slopes until the snowpack has adjusted to the warming conditions. 

Problemi valanghivi

  • Loose Wet

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

    Snow surfaces are getting wet and sloppy as warm air filters into the region. Tuesday will be day two of above-freezing temperatures at many lower elevations, so triggering these wet avalanches on any steep slope may be easy. While less likely, you could even encounter a wet slab if conditions align in the right spot. So you'll want to keep your plans simple by avoiding steep slopes - especially if you notice wet, sloppy snow under your feet or sled. 

    (12/7/2023)

    An example of a wet loose avalanche. 

    Photo: Willie Webster

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    You can still trigger large, surprising avalanches that break 2-4 ft deep. Assume this problem exists on all upper and middle elevation slopes and possibly shadier lower elevation slopes. These avalanches will be large enough to bury people. Although the slides will be largest in wind-loaded terrain, you can encounter this problem on all steep slopes, including those sheltered from the wind. Continued warming will only worsen matters, so widen your margin by sticking to simple terrain less than 30 degrees.

    A rider in the Manastash Ridge area remotely triggered one of these persistent slab avalanches on Sunday. This is good confirmation that the problem extends into the East South zone. Very large avalanches in the adjacent West South and avalanches to the north (East Central) also make it a good bet this problem also exists here. Weak facets exist on and within several crust layers buried deep in the snowpack. These avalanches could now be 2-4ft deep and potentially unsurvivable. With a few inches of new snow or rain, small storm slabs or wet avalanches could step down to these layers, producing a very large avalanche.

    (1/20/2024)

    A rider remotely triggered this avalanche near Manastash Ridge on Sunday, January 21st. We suspect that it ran on the Solstice Crust and similar avalanches are wide spread in the more eastern areas of the Cascades. 

    Photo: Chris Ofsthun

Avalanche Discussion

A complicated weather forecast makes for a complicated avalanche forecast. However, we do know the East South has a widespread weak snowpack, and this warming pattern is only becoming more pronounced, especially at the middle and lower elevations. This combination could make for dangerous avalanche conditions, especially in areas that just held dry snow recently.

Warming temperatures and rain on snow are something the east slopes of the Cascades haven't experienced for a while, and the snowpack is undergoing a big transition. As we step out into the mountains after these shifts, be prepared to make assessments as you travel, and don't be surprised to see strange or quickly changing conditions. Build wider margins into your travel plans to account for this, and pay attention to warning signs such as collapsing, shooting cracks, or recent avalanches. 

In addition to the avalanche on Manastash Ridge, multiple human-triggered avalanches have occurred near the Blewett Pass area over the past few days. These are failing on the Solstice Crust, and many have been remotely triggered from adjacent slopes. An NWAC forecaster at Crystal Mountain saw a suspiciously large avalanche in Morse Creek, very close to the border of East South. With avalanches and a lot of uncertainty, it's always a good default to more conservative terrain.

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

 

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