Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

Warm temperatures will maintain very dangerous avalanche conditions. You could easily trigger wet avalanches on steep slopes, and very large, wide avalanches could run into lower elevations from alpine terrain. Travel on or under any steep slope at upper elevations is not recommended. Don't linger in gullies where avalanches can run from above.

Problemi valanghivi

  • Wet Slabs

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

    The destructive and unpredictable nature of wet slab avalanches requires conservative decision-making. They may run naturally, so make sure you are aware of all overhead terrain. Travel quickly through runouts and gullies where large avalanches can funnel into lower elevations. Deep, widely propagating wet slabs are possible throughout the zone but may be more likely near Hart's Pass and farther east in the zone where the snowpack is shallower and weaker. Wet loose avalanches will also be widespread, so avoid steep slopes with heavy, saturated snow. Cornice failures and glide avalanches are also likely with the prolonged warm temperatures. Give wide margins to deep, glide cracks and overhanging cornices. 

    While an initial round of avalanches occurred with rain and warming on Sunday and Monday, upper elevations likely stayed as snow. Temperatures warmed into the mid-40°s at upper elevations on Tuesday, and overnight temperatures will remain above freezing.  The previously dry and layered snowpack had multiple weak interfaces. This lack of overnight refreeze, paired with the weak snowpack, is a recipe for wet slab avalanches.

    (3/2/2025)

    A wet slab avalanche ran thousands of vertical feet and crossed the Hart's Pass road in the East North zone earlier this month.

    Photo: Katie Warren

Avalanche Discussion

Another warm, sunny day is forecasted for Wednesday, with a chance of thunderstorms in the afternoon and overnight into Thursday. So if you plan to be out late in the day or overnight, prepare accordingly and get off ridglines and exposed terrain if tall, dark clouds begin building. Thunderstorms can bring heavy precipitation that could quickly increase the avalanche danger.

While every wet avalanche cycle plays out slightly differently, this specific setup seems quite similar to late February, when a rider was killed in an avalanche near Hart's Pass. The snowpack near Washington Pass and farther west in the zone started stronger before this warming event.  But even so, the extent of the rain and warming could easily bring this problem back to life. The northern and eastern areas of the zone with a shallow, weaker snowpack will be particularly susceptible to warming and rain. Consider the consequences of simply being in the wrong place at the wrong time if an avalanche runs into lower elevations from above. Choose your terrain wisely, paying attention to the terrain even thousands of vertical feet above you. Expect deep, challenging travel in unconsolidated wet snow. 

Before warming and rain, the January Drought Layer was buried 2–3.5 ft and shallower east of Mazama. Near Rainy and Easy Passes, the JDL is over 4 feet deep and capped with a thick melt-freeze crust. On March 17, an observer near Tiffany Mountain reported widely propagating recent natural avalanches and rolling collapses on a weak layer in the middle to lower half of the snowpack. Then, on March 22nd, another observer documented a recent natural slab avalanche near Mt. Tiffany that we believe was released on the JDL. Warm temperatures and rain make avalanches on these weak layers more likely. 

NWAC Forecasters visited the site of the avalanche fatality near Harts Pass that occurred on 2/28. The full accident report is published and can be found HERE. 

Submit an observation to the website or the Avy App to help NWAC Forecasters reduce uncertainty. It can be short, simple, and even anonymous. 

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