Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

Temperatures are cooling and we can expect to get one or two inches of snow in the zone. You might find small pockets of wind drifted snow at mid and upper elevations which shouldn't be enought to present a large hazard except in areas with terrain traps. Prepare for abrupt changes in conditions, as snow surfaces will become crusty.

Problemi valanghivi

  • Wind Slabs

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

    Only a couple inches of snow is expected to fall Tuesday night into Wednesday. Temperatures will continue to cool during the precipitation, so we expect new layers to mostly bond well to underlying layers. Areas to focus on where you might still be able to trigger a small avalanche is in wind slabs 4-6 inches or so deep in small pockets at mid and upper elevations.

    The perks of shallow new snow amounts is that you can easily use your hand to dig down to the underlying layer and check bonding between the new and old snow surface, or see if there are any stiffer wind slabs at the surface that can easily slide on the layer beneath it. You can use small test slopes to see if pockets slide. 

    If there are any small reactive slabs, it may not be much of a concern, except if you are in high-consequence terrain. This could be the case if you trigger a slab that knocks you off your feet above a cliff band, or you're caught in an avalanche that will carry you into trees, rocks, or a gully (terrain traps). If you choose to enter any of this high consequence terrain, be aware of snow conditions and consider where you might get carried if a small slide knocks you off your feet before deciding to enter the steep slopes. 

     

    (2/16/2024)

    Example photo: An unintentionally skier-triggered small, shallow wind slab in a confined rocky chute. Note the textured surface up against the rock wall, an indication of wind loading. Despite this being shallow, if you were caught in it the ride would be scary. 

Avalanche Discussion

Snow conditions on Tuesday were described as "manky" and "schmooey".  A forecaster found that this was the first day that north-facing slopes, even to upper elevations, became moist. He saw rollerballs running in steep due north terrain, but didn't see any full fledged wet loose avalanches. He also reported a D2+ wet avalanche that resulted from a cornice fall on Cos Creek Ridge on an east-facing slope at 6000ft.

Despite the usual irregular spring wet avalanche activity slowing with this rapid cooldown, it doesn't mean all activity will shut off overnight. A cornice fall still might happen as temperatures cool.  Small wet loose avalanches may happen at lower elevations, especially at the snowline interface where new snow may be moist. In these areas the old wet snow layer may not have much of a crust, so there's a chance some of the old snow could become entrained in a slide.

At higher elevations we expect a solid crust to form in the previously wet surface snow, on all aspects. Much of the snowpack, at least on upper elevation north aspects that only just became moist, still have a  winter-like snowpack. Under the surficial spring transition lie colder, drier layers and the potential for more surprises. Travelers over the weekend triggered numerous avalanches; some were caught, a few were carried and buried, and one was killed. 

Your avalanche, snowpack, or weather observations are extremely valuable to the avalanche community. Help create a more accurate accurate forecast by submitting your observations HERE. 

 

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