Bollettino valanghe

East 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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In sintesi

Warmer temperatures mean natural and triggered wet avalanches are possible. Move to lower-angle terrain if the snow feels heavy and wet. At upper elevations, you may still find lingering pockets of stiff, wind-drifted snow where you could trigger an avalanche, so steer around these deep drifts in steep terrain.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Over the past few days, winds formed pockets of unstable wind-drifted snow where you could trigger an avalanche. You may find that these wind slabs are still reactive in some locations. Steer around drifts on slopes steeper than 35 degrees. Cracking in the new snow, blowing snow, sharp cornices, and wind-sculpted features indicate that you may trigger a wind slab avalanche on nearby slopes. We expect most of these avalanches to be small but use caution in high-consequence terrain where a fall could have unfortunate outcomes. Cornice falls are common this time of year and are a hazard on their own, but they can also trigger slab avalanches on the slopes below. Don't linger for long beneath these monsters.

    (2/27/2024)

    An example of a skier-triggered wind slab avalanche on February 27th. Fisher Peak, E, 6,900ft

    Photo: NCH

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Freezing levels are on an upward trend and will creep close to 5000ft on Friday. The warm weather, sun breaks, and the potential for showers mean wet loose avalanches are possible in steep terrain. These avalanches are relatively predictable but can carry a lot of force, and they may become easy to trigger by the afternoon or run naturally. If the snow feels like wet mashed potatoes, it might be time to move to lower-angle terrain. 

    The snowpack at lower elevations has been through several melt-freeze cycles and is mostly well consolidated. However, you could still see blocks of snow shed off steep rocks and cliffs, so pay attention to the type of terrain overhead as you travel. 

    (3/17/2024)

    Wet loose avalanches often start from steep rocky terrain.

    Photo: Willie Webster

Avalanche Discussion

Springtime brings dynamic weather to the mountains, and afternoon warming can produce locally heavy bursts of precipitation. Travel with an assessment mindset, make frequent observations, and be prepared for rapidly changing conditions and snow stability. 

There have been a few observations of a poor bond to the most recent melt-freeze crust (3/22). So, use quick hand pits and test slopes to check this bond as you travel. If you find the recent snow slides easily, avalanches are more likely. 

We're removing the persistent slab problem for the time being. The structure still exists at upper elevations on northerly aspects, but avalanches or other indicators of instability haven't been observed for some time. Keep the dormant, persistent weak layers in your mind as we move through the Spring, and consider limiting your exposure to large, complex, and unsupported start zones at upper elevations. The last known avalanches on deeper weak layers occurred around the middle of the month during a prolonged period of very warm temperatures. 

Following the warm weather in the middle of March, temperatures cooled. A refreezing upper snowpack (at least at middle and upper elevations) has minimized snowpack concerns for avalanches occurring below the surface snow. On sun-exposed slopes, you may find a new host of new crusts that strengthen the snowpack. Where the snowpack stayed primarily dry, you may be able to find a few older weak layers in the upper to middle of the snowpack. These include the March 9th strong-over-weak interface that's 1-2 feet below the surface. Also, the weak layers of February 25th, mid-February, and the January 31st crust are all within 1 foot of each other 2-4 feet below the surface.

Snowpack information is limited. Let us know what you find if you get out into the backcountry!

Regioni coperte