Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

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

A winter storm will bring a few inches of snow to the Pass Friday and slowly increase the avalanche danger. You may encounter a few unstable pockets of wind drifted snow especially later in the day. Blowing snow and sharp thin cornices can help you anticipate potentially loaded slopes you may want to avoid.

Problemi valanghivi

  • Wind Slabs

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

    Strengthening winds should easily turn the few inches of new snow into a fresh batch of shallow slabs on the lee sides of ridges and near the base of cliffs. Since we’re expecting the bulk of the precipitation in the afternoon, it may take a bit for this problem to develop. Fortunately, the stormy weather should provide you with plenty of clues to help you figure out where this issue is actively forming. While these slabs should remain rather small, they could trigger easily over recent crust. So, don’t let one catch you off guard if you’re traveling above a cliff or other terrain trap that could magnify the consequences of even a small avalanche.

    (2/18/2023)

    Signs of wind loading to look for Friday.

    Photo: Dallas Glass

Avalanche Discussion

First thing in the morning, you may find generally safe avalanche conditions (Low danger) around the Pass. Colder and cloudier weather should help the snowpack freeze and become strong. As more snow accumulates, expect the hazard to rise. When exactly the danger will increase is tough to say, but if you find a few inches of new snow and see blowing snow, it’s time to start thinking about wind slabs.

Given the recent weather, we’re most concerned about the new snow and its bond to the older surface. How the snow sticks to the new interface (3/30) is hard to predict. On Thursday, an avalanche professional in the Apental valley found warm moist snow. If the new snow falls before it freezes, it may bond very well. If a firm crust forms first, the new snow may slide easily. You can use hand pits and uptrack tests to see if the snow fails suddenly and/or in slab-like blocks. 

Prior to this storm, a variety of surfaces existed around the Pass. While warm moist snow was the most prevalent, firm wind-pressed snow, textured surfaces, scoured slopes, breakable crust, loads of tree debris, and frozen avalanche debris were found. On Friday, some of these obstacles may only be buried by an inch or two of new snow.

The storm will continue Friday night. As it intensifies expect the avalanche danger across the zone to rise rapidly. 

Regioni coperte