Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
4 · Forte
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In sintesi

Very dangerous avalanche conditions exist. Plan your travel by avoiding all avalanche terrain on Wednesday at all elevations, which includes where avalanches start, run and stop. This also means if you're on a road or hiking trail at lower elevations, this isn't a day to cross a gully or open slope that might connect to a large avalanche path on a mountain several thousand feet above. 

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    2–3

    Rising temperatures, strong winds, and about 3 feet of snow by the end of the day Wednesday are forecasted. This is a great recipe for natural avalanches, which may reach very large in size, as we will probably end up totaling 4 to 6+ feet of snow since the 24th. It's not out of the question that all this recent snow may slide. There's even a very small chance that snow could slide a foot or two deeper than these recent layers, all the way down to the Early February Crust, where in some places we've been finding weak snow above the crust. Avoid traveling in all avalanche terrain, including flat or lower-angle terrain beneath large steep slopes, which you might not even be able to see up above you. It will likely be unsurvivable if you trigger or get caught in an avalanche. 

    Last year, some unsuspecting folks drove up Church Mtn Rd off Hwy 542 right after a huge snowstorm. There was no snow where they drove. In the couple hours they were up there, a very large natural avalanche came down a subtle gully and their vehicle was trapped behind a debris pile well over 10 feet deep. It was stuck there for at least a month. Wednesday could be a day like this, so don't get lulled into complacency by traveling in a lower elevation area where there is very little snow, thinking that it means you're alright. Beware of traveling across subtle gullies and abrupt swaths of smaller trees next to large trees (that might indicate an avalanche sweeps through the area) at lower elevations if there are steep mountains nearby. 

    (2/21/2023)

    A sneaky avalanche that came down Church Mountain in a tight gully, almost exactly a year ago. Debris blocked the Church Mt Road above Hwy 542 over 10ft deep, and a car was stuck on the other side for a lengthy period.

  • Loose Wet

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

    Snowlines are rising throughout the day on Wednesday. There's 1-2 feet of fresh snow at the upper parts of the lower elevation band, and snowline is forecasted to rise to about 4000ft. Previously cold dry snow will get heavy, wet snow on it, and some rain as well, so wet loose avalanche could result.

    Avalanches will start shallow, running in the top few inches of the snow. As more rain falls, avalanches could grow deeper, with the chance of a wet slide wiping out all the snow above the Early February Crust. This may only be about 6 inches deep at 3500ft if there is a smooth surface for the snow to run on, but when we're getting above 4000ft, there might be closer to 2 feet of wet snow running down a slope, enough to cause serious harm if you're caught.  This is one more reason to avoid travel on or below steep slopes on Wednesday. 

    (1/27/2024)

    Example photo: Large wet loose avalanches may run deep and far as the day progresses. 

    Photo: Pete Durr - USFS

Avalanche Discussion

Avalanche activity will likely increase throughout the day as more snow falls, and it gets heavier and more wind-affected. We expect natural avalanches to start overnight and continue throughout the day.  Some avalanches may only occur in the newest snow layer, which might be 1-3 feet deep. But avalanches may fail 6 or more feet deep, taking all of February's snowpack with it. Visibility will likely be poor, and you won't be able to see either overhead hazards like avalanches coming down or even hazards like cornices or wind lips right in front of you, that you might fall off of. 

Observers in the last few days reported a whole variety of conditions. In some non wind-affected areas backcountry travelers only encountered dry loose avalanches and good riding conditions. However, two very large, natural slab avalanches were found in the last two days, one at Canyon Creek and the other across Hwy 542 at Glacier Creek. These propagated surprisingly far and may have failed on a weak snow layer above the Early February Crust. In some places we've found concerning results on the layer above the Early February Crust, and in other areas we haven't found much weakness. We believe avalanches failing down to this layer will probably be few and far between on Wednesday, but we're not quite sure. A number of other weak interfaces exist above the Early February Crust, which are all layers we may see avalanches failing on during Wednesday's storm. 

Travel will be very challenging as snow gets heavier and deeper. Snow immersion syndrome is a very real hazard for Wednesday. You could be trapped by trees, but there are also many subtly hidden creek holes and other holes that have been recently covered that you could get trapped in. Winds will be ripping around on mountaintops, valleys, and everywhere in between. Expect an adventurous day in the mountains with heavy snow, rain, and wind on Wednesday. 

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