Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

A quick transition back to a cooler storm happens Thursday night after warm temperatures wetted the previously dry snow. Pay attention to newly wind drifted deposits, as that is where your largest avalanche concern lies. If you encounter heavier-feeling drifts deeper than 6 inches that don't stick well to the underlying snow, steer around nearby steep slopes. 

Problemi valanghivi

  • Wind Slabs

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

    Wind slabs will develop throughout the day as we'll see moderate to strong winds shifting new snow around.  Friday will start with minimal development, but snowfall amounts could reach six or more inches by Friday evening. Your main concern is triggering a slab avalanche in a newly drifted pocket of snow. Thursday we saw surfaces wetting on all aspects and elevations, quite possibly up to the top of our above treeline forecast zone.

    We are uncertain about the condition of the old snow surface as new snow starts to fall. Temperatures will plummet as the precipitation begins, and if the older layer is still moist, new snow could insulate the old snow, keeping it damp for longer, and the fresh snow could stick better to the old layer. If the old layer freezes first, newly fallen snow may easily slide on the older layer. The new layer will not amount to much, so you can quickly dig down with your hand to check the interface between new and old layers and determine how easily the snow slides. We only expect areas with thicker wind drifts to avalanche. You're most likely to find them around rocky outcroppings, in gullies and on leeward sides of features. Search for indicators like cracking, and avoid steep slopes if you encounter cracking, or find thicker drifts in areas where the new and old layers are not well bonded. 

    (3/20/2022)

    It is possible that small wind slab avalanches similar to this one could be triggered by a human on Thursday.

    Photo: Ryan Minton

  • Loose Wet

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

    Small wet loose avalanches may still occur at lower elevations earlier in the day. However, the incoming cooler temperatures are expected to reduce the likelihood of wet slides as the day progresses. If you're traveling through lower elevation areas and the snow is punchy and you're easily sinking in to your knees or deeper, remain alert for small natural wet loose avalanches or you triggering one on a steep slope. When the surface starts firming up, and isn't as loose and incohesive as the rest of the underlying snow this avalanche problem is probably behind us.

    If there are any brief sun breaks during the day, it might be enough heat for new low-density dry snow to begin sending rollerballs down or small wet loose avalanches in steep areas. If you see the sun at all on Thursday, expect to encounter these conditions on south-facing slopes. 

    (3/31/2022) Small rollerballs or wet loose avalanches may still occur on Friday morning. Photo: Josh Hirshberg

Avalanche Discussion

We didn't hear any reports of large slab avalanches occurring near the bottom of the previous storm snow layer, around 3 feet deep, on Thursday. Warm temperatures and the wetted and possibly refrozen surface layers are further reducing the chances of large slab avalanches occurring. If you travel to upper elevations, and especially if you don't find an obvious previously wet underlying layer, remain aware of this concern on steep wind-loaded slopes. A human probably couldn't trigger one of these deeper avalanches, but a large, sagging cornice that falls or another smaller avalanche might provide enough weight to trigger a large avalanche. 

This week has been a rollercoaster. Sunday through Tuesday 2-3+ feet of snow fell in the mountains of the West Central Zone, and we had some of the best powder snow of the year Tuesday for snowmobilers, skiers and riders, and snowshoers. Tuesday was the day to get out if you're into dry, deep powder because freezing levels skyrocketed to over 10000 feet Thursday, and snow became wet on all aspects and up to every elevation aside from the highest summits. Wet loose avalanches were reported in nearly all the zones. Just one day later, freezing levels are forecasted to drop to 3500ft by Friday evening and more cooler temperatures and snow are expected through the weekend and beyond.  This huge variety of weather means snow conditions are variable, with soft wet snow, crusts and some more dry snow to keep travel adventurous on Friday.

Regioni coperte