Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Rain fell on a thick layer of light, dry storm snow on Monday, and many wet avalanches ran in surface layers. We don't expect as many avalanches Tuesday, but any that happen will likely be larger and less predictable than the previous day's. Stick to lower-angle terrain on Tuesday, and if you see large, natural avalanches coming down, give lower-angle slopes beneath large avalanche paths plenty of clearance as well. 

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5

    After the initial rain-on-snow event on Monday, we expect avalanche activity to slow. But temperatures are staying warm, and it'll continue to rain, so as water impacts deeper into the snowpack, larger avalanches could release, although probably less frequently than the previous day. 

    On Monday, wet loose avalanches ran. At some point, wet slabs are expected to start releasing.  It's extremely challenging to predict when we'll start seeing these large, scary, and highly unpredictable avalanches. We think they'll really kick off Tuesday night when rain picks up, but they might happen sooner. Wet loose avalanches are expected to continue running at less frequent intervals, but they could gouge deeper and run farther than the previous day. 

    Avoid traveling on any steep slopes on Tuesday. If you see natural avalanches coming down, steer around the bottom of avalanche paths as well. This is also a day to not linger beneath skinny, tight gullies even at lower elevations that connect to higher-elevation terrain. 

    A large natural wet slab avalanche, like one you might see on Tuesday. If these frequently come running down, avalanche danger is higher and you should avoid all avalanche terrain. 

Avalanche Discussion

About 1-1.5 inches of rain fell in the zone Sunday night and Monday. A small wet avalanche cycle likely happened early Monday morning. Low clouds broke up in the afternoon, and I was able to see wet loose avalanches had run on most steep slopes in the Highway 2 corridor.

Around half an inch of rain is expected to fall Monday night, and similar amounts again during the day. From the southern part of the Mtn Loop down to Snoqualmie Pass, there's about 2 feet of snow sitting over the 3/12 crust. Further north, we suspect there's only about a foot. We expect water to eventually percolate down to the 3/12 crust, and potentially lubricate above the crust, resulting in wet slab avalanches. Further north, where there's less snow over the crust, wet slab avalanches could happen sooner than to the south. 

When rainfall amounts pick up Tuesday night, we expect a natural wet slab cycle, with lingering very large and highly unpredictable natural wet-slab avalanches continuing into Wednesday. We don't think slab avalanches will step down below the 3/12 crust, but it's not completely off the table that an even larger, deeper one could happen. 

Expect challenging travel conditions with rain and deep, wet snow on Tuesday. 

Regions covered