Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

Colder temperatures, windy conditions, and incremental minor additions of snowfall maintain the risk of small slabs you can trigger. Your attention should focus on lee slopes 35 degrees and steeper as dry snow depths increase. Wind loading patterns favored atypical aspects, so note the direction of corniced cornices that point toward the hazard.

Problemi valanghivi

  • Wind Slabs

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

    We're expecting 1-2" of snowfall Wednesday night with moderate winds drifting fresh and recent snow. While most of the winds transport snow onto shaded aspects on the north side of the compass, persistent low-level E winds could help cross-load some mid-slope features or favor atypical aspects. Look for visual clues including cracking, lens-shaped pillows of recent snow, or fresh, sharp cornices overlying suspect slopes. You can also feel for wind-stiffened snow above less dense layers that sit above a crust. If you find any of these signs in your terrain, navigate away from wind-loaded slopes steeper than 35 degrees. Be suspicious of any wind-stiffened snow, wind deposition zones, or the freshly formed cornices that overhang them. In some cases, slabs may overly weaker snow layers such as surface hoar and depth hoar within the shallow snowpacks of the zone. Consider steering around steep terrain if you encounter whumphs or long cracks that shoot away from you.   While we expect any avalanches to be small, consider the high consequences of a fall in steep terrain with exposed obstacles. 

     

    (12/26/2023)

    Wind textured surfaces and drifts indicate slabs may be present on nearby lee slopes.

    Photo: Katie Warren

Avalanche Discussion

Challenging travel at lower elevations have limited recent observations. As we move further away from recent reports, our uncertainty about the state of the snowpack may gradually diverge from reality. Consider this added uncertainty in your planning and consider making your own snowpack assessments before committing to terrain of consequence. 

Precipitation ends early Thursday with mostly cloudy skies expected. With mild temperatures into the 30s expected and the possibility of some sun, expect the potential for wet loose avalanches involving any recent dry snow. Limit your exposure to steep sun-affected slopes if you see evidence that the snow is warming up, such as rollerballs or snow melting off rocks and cliffs.

We think that milder temperatures likely formed crusts up to middle elevations in many areas of this zone on Wednesday. Thus, heightened avalanche danger focuses on upper elevations with drier surface snow accumulating over the last few waves of precipitation. Aspects on the northern half of the compass likely stayed colder and could drag the risk down into middle elevations in some areas.   Incremental additions of snowfall from recent storms should be available for transport on the northern half of the compass. Each wave of moisture that moves through the zone brings several inches of snow to the ES zone, but some areas don't receive any snow at all with another such wave of limited moisture arriving Wednesday night.

The mild temperatures have also decreased snow depths significantly. New snow may fall on bare ground on south-facing slopes at mid and lower elevations. There is plenty of brush to contend with as well. Rocks and boulders may still be exposed or barely covered with fresh snow. Consider staying on summer trails and roads to access higher elevations for more manageable travel.

Slick crusts, surface hoar, and weak snow surfaces are prevalent and have been identified on 12/26 in the Mission Ridge area. Use quick hand pits or test slopes to see how the snow reacts. The new snow that slides easily off old surfaces indicates that avalanches are more likely. 

You can contribute to the forecast! Let us know what you found by submitting an observation HERE. 

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