Lawinenlagebericht

West Slopes North

Northwest Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Avalanche danger is increasing with continued wind and snow overnight and during the day Thursday. You could trigger an avalanche on wind-loaded leeward features on Friday, so steer around thicker, wind-drifted snow deposits on steep slopes, especially as the day continues and drifts get deeper. Damp conditions at lower elevations may cause wet loose avalanches in previously dry low density snow. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    Wind slabs are expected to grow in size and become more reactive to a human trigger on Thursday. Wednesday afternoon wind increased and significant snow transport was witnessed. Wind is expected to continue at similar speeds on Thursday, with the addition of a few inches of snow. Expect danger to increase throughout the day as snowfall continues. Danger is highest at upper elevations, where more snow will fall and become more wind-affected. You may be able to find small wind slabs as far down in elevation as the upper portions of below treeline areas. 

    This will be a good day to pay attention to actively loading snow. You will likely see plumes of snow, or flagging, blowing from ridgelines like in the accompanying photo. Expect thick pillows to form where the snow falls, which will likely be reactive to a human trigger. Reactive slabs will mainly be composed of new drifts which began forming Wednesday, or possibly just from Thursday. These drifts could be over a foot deep, especially later in the day.  Areas you can expect to find them are on leeward slopes which include convex rollovers, gully walls, or around rock outcroppings and cliffs. Long shooting cracks breaking from your feet are indicators of weaknesses in the snowpack. Steer around wind loaded slopes greater than 35 degrees on Thursday. 

     

    (1/4/2023)

    Intense wind transport and cornice formation on Ptarmigan Ridge on Wednesday. Expect more of this Thursday, with several inches of new snow available for transport as well. Note where wind deposits, possibly forming into reactive wind slabs. 

    Photo: Lee Lazzara

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1

    Freezing levels may rise as high as 4500ft by Thursday afternoon. Precipitation will likely fall as rain in much of the below treeline elevations. Moist snow is expected near the rain/snow interface. Some below treeline areas, especially on shady aspects, may have a foot or more of low density snow over the Christmas crust. Southerly aspects likely have shallower amounts of new snow over the crust, and became sun affected on Sunday. The already sun affected areas will probably be less likely to slide. If previously low density gets rained on, or new moist snow falls, you may see small natural wet loose avalanches. You may be able to trigger small avalanches on steep slopes as well. If you see wet loose avalanches or rollerballs running downslope, avoid similar steep slopes. 

    (12/3/2022)

    If you see rollerballs, these are signs that the snow surface is becoming wet and weak. 

    Photo: Zack McGill- Cascade Mtn Ascents

Avalanche Discussion

Snow conditions are variable right now, from surprising pockets of low density snow that still haven't been affected by the last few days' wind, to a variety of wind-affected surfaces. Steep southerly aspects formed a sun crust on Sunday, which you'll probably still be able to find during your Thursday outing. Some lower elevation areas are still hanging onto low density snow, while snow has gotten heavier in other spots. Expect to see some change in these conditions as our next system brings snow and rain starting Wednesday night. 

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