Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

It'll be hotter and sunnier on Wednesday and more wet avalanches will probably run on steep slopes facing the sun. Nearby rollerballs or slides, or just plain wet, sticky snow, are all signs that its time to avoid steep sunny slopes and the terrain beneath them. You might still be able to trigger an avalanche on wind lodaded slopes at upper elevations. 

Avalanche problems

  • Loose Wet

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

    Wet loose avalanche activity will increase as the day continues. Avalanches may start on more easterly slopes in the morning before shifting south midday, and then towards the west in the afternoon. We expect an overnight freeze Tuesday night, so lower elevations and slopes that have already been impacted by the sun will start out with a crust on them. Expect these crusts to soften as the sun and warm temperatures impacts them. 

    Over the last few days we've seen a mix of sun and clouds, and increasingly warmer temperatures. Some wet avalanches have already happened. There isn't much light, fluffy snow still sitting on steep slopes facing the sun. For this reason, we aren't sure exactly how much wet avalanche activity we'll see on Wednesday. 

    It's up to you to evaluate snow and avalanche conditions and determine how to manage your terrain. If the snow becomes wet and heavy, or if you are already seeing rollerballs or small avalanches, these are obvious signs to avoid similar steep slopes or traveling in the terrain beneath those steep slopes. Stick to lower angle terrain away from steep sunny slopes, or move to shadier aspects. Areas that may not have produced avalanches in the morning when you first traveled by them may be producing avalanches later in the day. Plan your trip so you don't get caught out by wet avalanches upon your return. 

    Example photo: Rollerballs and wet loose avalanches like what you may see on Wednesday. 

    Photo: Brad C

  • Wind Slabs

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

    You may still be able to find a wind slab that could avalanche with a human trigger at upper elevations on Wednesday. If you do trigger a wind slab, there's a good chance that it will be in a high consequence area, like if you're in a gully, around rock features, or in a cliffy area with a steep, unsupported slope. An avalanche could also be triggered on the leeward side of a ridge, where wind deposits snow. Taking a ride in any of these areas wouldn't be ideal. You might get buried deep in a gully or at an abrupt bench, or sent off a cliff.

    We aren't sure how reactive any of these wind slabs still are at higher elevations. Most drifts will likely be 6 inches to a foot deep, but they could be 2 or more feet deep. At this point, there's probably a pretty low likelihood that you'll find and trigger an avalanche on a wind slab, but if you do it could be bad, due to the terrain you're in. Be sure to stop and reevaluate when you're shifting aspects, elevations, and especially if you're going to enter high consequence terrain. 

    Scan the snow surface for wind-effect: search for smooth pillows or textured surfaces as indicators that the wind affected these areas. Feel and assess for heavier or stiffer snow beneath you. Dig down to the old snow layer near the most recent crust, which could be 6 inches or a couple feet and check the bond. Does the surface layer easily pop off, or does everything stay glued together? If you have any doubt, avoid traveling in terrain steeper than 35°.

Avalanche Discussion

Many human triggered and natural avalanches were reported over the weekend in neighboring zones. Snow fell Friday night but it wasn't until Sunday that most people were stepping out and testing steep terrain. The stars aligns with beautiful weather, a healthy coating of new snow, and peoples' days off. There was a natural avalanche that ran in a tight gully in the Snoqualmie zone, likely Monday night (OBSERVATION), so there may still be some odd avalanches out there, even if we suspect most instabilities have strengthened.

We suspect most avalanches failed in the new snow layer or beneath wind slabs, but there's a chance that avalanches may have failed on a crust, or where there may be weak layers buried in the top couple feet of snow. Depending on where you are in the zone, danger could differ and it might be easier or harder to trigger an avalanche. 

Snow surfaces vary highly. A firm melt freeze crust exists at lower elevations and steep, sunny slopes, but will likely soften as the day progresses. Wind stripped and textured, firmer surfaces appear in many other areas. Sheltered mid or upper terrain may still harbor some soft snow, maybe. If you make it into the backcountry to enjoy this warm sunny day, even if just for a walk in or near the snow, please share with us what you saw by submitting an observation HERE or on the App. 

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