Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
Senza grado
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In sintesi

Don't be lulled into a false sense of security if you're out on snow on this one nice day between the storms. A couple feet of new snow at higher elevations hasn't had time to adjust: stick to lower-angle, smaller slopes if you make it up high. Wet surfaces may have frozen, but the snowpack is still quite saturated- lingering wet avalanches could still happen. 

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Use conservative decision-making when you find dry snow as you climb higher.  Thick slabs may just be waiting for a human trigger to avalanche,  as the storm's layers may not be set up well due to mid-storm warming or wind-effect, resulting in an "upside down" snowpack.  The most dangerous areas will be steep leeward sides of ridges where strong winds drifted snow into deeper slabs. However, areas that aren't wind-affected are still suspect. 

    Stick to lower-angle slopes and smaller terrain features. Even if there are trees or shrubs poking through an area, it doesn't mean it's impervious to avalanches. Search for clues like long, shooting cracks and recent signs of avalanches as obvious indicators to avoid steep slopes- but even if these clues are absent, this isn't the day to tempt fate by stepping out onto big, steep slopes up high. 

     

    Example photo: You could trigger storm slab avalanches where slopes roll over and get steeper.  Don't get caught out on one on Tuesday. 

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Large amounts of rain reached as high as the upper elevation band on Monday and Monday night. Peak wet avalanche activity likely occurred then, but some lingering wet snow problems may persist as water percolates further into the snowpack. In areas with shallower amounts of snow, up through the mid-elevation band, wet avalanches could still happen.

    There's probably a higher chance of any wet avalanche activity being an odd natural avalanche, rather than one that you trigger. Considering the shallower snowpack, a wet avalanche might involve the entire depth of the snow, up to a couple feet deep. A slide may start as a loose point release, or it's not out of the question that a glide avalanche may happen. Given the uncertainty of this lingering hazard, consider steering around large, steep slopes, even if the snow cover isn't completely  smooth and consistent. 

    Example photo: Variable snow cover and rock surfaces could be prime areas where lingering wet avalanches could run on Tuesday. 

    Photo: Matt Primomo

Avalanche Discussion

We suspect there's a lot of new snow at higher elevations, but there's also been a shortage of information given the stormy weather lately. Large amounts of precipitation fell Monday and through the night, which totalled over 3 inches of water. The top of the upper elevation band probably has several feet of new snow. Fluctuating snowline resulted in further net losses of snow in the mid and the lower elevation band, where there hasn't been enough snow to constitute a forecast. 

We have a brief reprieve between atmospheric rivers on Tuesday before even higher freezing levels and larger amounts of precipitation enter the area Tuesday night. The tail end of the storm early Tuesday morning may result in a couple inches of dry snow over the wet layer, which could slide on the wet snow beneath it. 

With the warm start to the 25-26 winter season, we have less snowpack information than usual to start daily forecast operations. For zones and elevation bands with less snow than needed for avalanche hazard, we will issue a forecast with No Rating. Anticipated avalanche and weather conditions will still be updated daily. NWAC will issue an avalanche danger rating for a zone when enough snow to produce avalanches has accumulated at middle and upper elevations

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