Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Wet snow avalanches may remain a problem, so if you notice snow getting moist or starting to roll downhill on the southerly half of the compass, shift your travels away from steep nearby slopes.  We've had large human-triggered slab avalanches resulting in injuries in the last few days, and it's difficult to identify which pockets of snow will react to a human trigger. Consider steering around steep terrain, especially on large slopes or high-consequence areas to reduce your chances of getting caught in a dangerous avalanche.

Avalanche problems

  • Loose Wet

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

    Moist rollerballs started running downslope by 10am Thursday.  On Friday, the intense sun will have to cook its way through the previous day's crust, but temperatures are forecasted to be a little warmer and we suspect we'll have another round of wet loose avalanche activity to look forward to on Friday. Easterly slopes will warm up first, before transitioning to south and then westerly slopes in the afternoon. The span of wet loose avalanches may be a little larger than the previous day. 

    Pay attention to snow beneath your feet and on nearby steep slopes. When you notice it becoming moist and if snow begins rolling on steep slopes steer around those areas and the lower angle terrain beneath those steep slopes. We don't expect wet loose avalanches to get too deep at this point, probably less than a foot in depth, but depending on the amount of heat we get from the sun and how deeply you're sinking into wet snow, there's a chance avalanches could run deeper. There is a small chance that a wet loose avalanche could step down and trigger a larger slab avalanche. 

    (3/16/2023)

    Small rollerballs began rolling at around 10am on steep, south-facing terrain on Thursday in Bagley Basin. 

    Photo: Keeley Rideout

  • Wind Slabs

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

    A large human-triggered slab avalanche took someone for a scary ride, resulting in injuries, on Wednesday on Slate Mtn in the Baker backcountry. You can read the preliminary report HERE. On Tuesday another human-triggered avalanche occurred on the traverse out to the Arm in the Baker backcountry, which was triggered on the exact tracks that several people had already taken that day. You can read this observation HERE. I was at the Baker NRA on Tuesday and saw 2 human-triggered avalanches and you can read the observation HERE. 

    Most of the avalanches we've seen don't fit cleanly into the wind slab category. Recent 2-3ft deep avalanches have likely been failing on the new snow/old snow interface. Some slopes slid while similar neighboring slopes did not. We believe these avalanches are occurring in areas where wind may have deposited slightly thicker layers, but differentiating between the slopes that may slide and the neighboring ones that don't is borderline impossible. Surfaces in most areas look similarly wind-affected so you can't identify them that way. 

    As each day passes we believe the layer is gaining strength, but we still suspect someone could find one of these sneaky slopes and trigger a large, possibly unsurvivable avalanche on it.A lot of people ventured onto steep terrain on Thursday and didn't trigger avalanches, but we're hesitant to say this problem has completely gone away.  Consider shifting your travels to simpler terrain. Avoid steep and very large slopes, or areas that contain terrain traps like very steep, cliffy, or sparsely tree-covered committing terrain for the time being.  If you see any obvious red flags such as long shooting cracks from your feet or sled, or recent nearby avalanches, avoid nearby steep slopes. If you do see any newly developed wind slabs consider steering around the new deposits on steep slopes.  When in doubt, steer around slopes greater than 35°. 

    (3/14/2023)

    Human triggered slab avalanche 2-3' deep along the traverse to Shuksan Arm. Numerous people had crossed the slope in the same area before it finally released in the early afternoon. ESE at 5300'.

    Photo: Geddy Miller

Avalanche Discussion

Variable surfaces now exist, where lower elevation terrain and the southerly half will now start the day with a crust. It's likely to break down during the day and get moist. Along the same lines, during this first period of springlike warming it's a good idea to start paying attention to nearby cornices. They're very large and overhanging. Travel quickly or avoid areas beneath them, and stay several feet away from their edges. If there's anything that is going to trigger a large avalanche, they're going to be it. 

About 2-3 feet of snow fell Sunday into Monday through much of the zone, and a few additional inches fell Tuesday night. The majority of the snow was relatively heavy. North-facing terrain will continue to hold onto dry snow while the skies remain clear, although temperatures will spike much higher on Saturday. 

Regions covered