Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

The brunt of this Cascades storm converged on the southern half of the West Central zone, where we received around 4 inches of water by Monday evening. High precipitation amounts will continue Monday night before slowing down during the day. Steer around all steep slopes on Tuesday, but if you make it above treeline, destructive and large natural slab avalanches could still be likely so steer around the lower angle terrain beneath large avalanche paths as well. 

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1.5–2.5

    Above treeline, large, destructive natural avalanches could occur as the storm winds down. Avalanche activity is likely to peak overnight, but travel conservatively on Tuesday as we just saw a very large load of new snow in a short time frame.  Avalanches will probably be most active earlier in the day.  More reactive slopes will likely be thicker and stiffer wind slab deposits. Depending on where you are, there could be 4 or more feet of new snow at upper elevations, and below treeline could see up to a foot of new dry snow over the previously wet snow as temperatures get very chilly overnight and for the next few days. 

    Above treeline, steer around large avalanche paths and the lower angle runouts beneath steep slopes. At lower elevations avoid all slopes steeper than 35 degrees, giving the storm snow time to settle. It goes without saying that if you see any new avalanches, or your feet or sled initiates long, shooting cracks, stick to lower-angle terrain. Taking into account the timing and amounts of snowfall, wind, and overnight cooling temperatures, avalanche reactivity could vary widely throughout the zone. Evaluate conditions and adjust the forecast as needed for your travels. 

     At all elevations, you can expect to encounter dry loose avalanches, or sluffs, in steep, non wind-affected areas in the lower density, dry surface snow that fell overnight. They will likely remain small, but be aware of them knocking you or a partner over.

    Example of a human triggered avalanche, about 1 foot deep in recently fallen snow. This is similar to what you might find on Tuesday, or avalanches could be much deeper.  

    Photo: Stephen Semanski

Avalanche Discussion

Avalanche Accident Colchuck Pk, East Central Zone

We’ve received preliminary information of an avalanche incident on Colchuck Peak, SW of Leavenworth, WA. (East Central Zone) The accident occurred on Sunday, February 19 and involved a group of 6 backcountry travelers. Three members of the group are suspected to have been buried and perished in the event. Another sustained injuries and was evacuated by SAR.  Rescue efforts are ongoing. NWAC is working with Chelan County Sheriff’s office and will make updates as more information becomes available.

 Forecast Discussion:

In neighboring zones it's been just over a week since we've heard about large avalanches failing on deeper layers in the snowpack on subtle weaknesses near crusts. We don't expect a large number of avalanches to occur down at this layer, which could possibly be 4-6 feet deep, but we're keeping it on our radar through this storm. If an avalanche does occur, it will be very large and destructive, easily traveling below treeline. 

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