Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

It's likely that you could trigger a large wind slab avalanche above treeline, although chances of triggering one and the size may vary throughout the zone. Steer around steep, wind-loaded terrain as that is most concerning, or any other locations where you see obvious clues like recent avalanches or if you experience long, shooting cracks or whumphs. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Few human-triggered slab avalanches were reported in the Baker backcountry on Tuesday, although several dry loose avalanches were noted. Meanwhile, further south in the zone, large human-triggered slab avalanches were reported.  A day out from this large storm, the place where you're most likely to trigger an avalanche is on a wind slab.  Above treeline is mainly where you'll find reactive wind-loaded features.

    The storm layer itself is several feet thick, especially as you go higher in elevation. However, subtle changes from the wind in the top couple feet of snow likely formed more reactive pockets and are what will get you into trouble during your outing. These reactive layers may only be 1-2ft deep, but there's a small chance they could run deeper. Pay attention to clues such as textured snow surfaces or wind-sculpted features. Feel for heavier snow beneath you. If you find any of these characteristics, or identify any other obvious clues of instability, steer around slopes greater than 35 degrees.  

    (2/21/2023)

    Small to large (D1-D2) human triggered slab avalanches were likely at the Baker NRA on Tuesday. Note the wind-textured surfaces, and also the locations on a steep, convex slope, of where an avalanche might occur. 

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    The top foot or so of snow is cold, low-density powder. Temperatures will stay cool and this top layer could sluff, or loose avalanche, easily on steep slopes. This was noted by my coworker in the Baker backcountry on Tuesday. You can read about it HERE.  Sluffs could occur naturally on steep features, or they'd be more likely to occur if you venture out onto steep slopes and the snow starts sliding at your feet. The sliding layers may only entrain the top few inches of snow, but they could travel up to a foot deep, becoming slightly larger and more destructive.  This type of avalanche tends to be more predictable, but be sure to pay attention to them if you're in steep terrain so a sluff doesn't take you out from behind, or hit a partner. 

    There's the slightest chance that the sun could poke out, and if it does be aware of a subtle shift to some small wetter loose avalanches, although this is not expected. 

    (2/21/2023)

    A small dry loose avalanche which occurred naturally in the Swift Creek area of the Baker backcountry. 

    Photo: Lee Lazzara

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:

Early Tuesday morning a very large natural avalanche occurred not far from Glacier. It originated on the ridgeline just east of Fossil Mountain, and ran down over East Church Rd, FS 3040. It trapped a vehicle on the wrong side of the road and left debris piles 10 feet deep on the road.  The avalanche likely started about 4000ft above the road. This is the only record we have of such a large avalanche from the last storm cycle in the area. This was likely near the peak of instability, just as the storm's intensity was dying down.  It brings up a good point that even if you're traveling at lower elevations where little or not much snow is present, large avalanches can travel from far above during and just after storm cycles, hitting trails or roads far below, potentially causing serious damage. 

Storm totals varied all over the place in the West North zone, but we believe that anywhere from 3-6 feet of snow fell at upper elevations in the zone. At lower elevations, much of the first half of the storm fell as rain, so snow totals are smaller and areas aren't as wind-affected. At these locations, the snowpack is generally more right side up and our larger concerns are loose snow avalanches. Keep in mind that even if any type of avalanche is small, if a terrain trap is below you it could be deadly. 

 

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