Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

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

Wind slabs may be reactive to human triggering, and may become more dangerous with increasing winds during the day. Look for these especially at upper elevations and in exposed terrain. Loose dry avalanches could release below very steep, and rocky terrain. Avoid areas where you find wind-affected snow on steep slopes, and be ready to take a step back if you find increasing snow transport and signs of instability such as shooting cracks or recent slides.

Avalanche problems

  • Wind Slabs

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

    Strong westerly ridgeline winds will transport snow onto lee slopes, and winds will pick up during the afternoon on Saturday.  You'll find firmer wind-affected snow near and above treeline and even on open slopes below treeline.  Shooting cracks or hollow-sounding snow are signs you could trigger an avalanche on similar nearby slopes.  Avoid open slopes steeper than 35 degrees where you find freshly drifted snow, sticking to lower angle or wind-sheltered terrain.  

    In wind-sheltered terrain and for areas near the Cascade crest, you may trigger a storm slab avalanche.  Steer around convex rollovers and very steep unsupported slopes in areas you find more than 6" of new snow.  Dry loose avalanches are possible on slopes steeper than 40 degrees with unconsolidated new snow.  Limit, or avoid exposure below cliffy terrain if you see snow moving around or spindrifting off of rocky cliff faces.

    Example of active wind drifting snow. Notice the fracture near the edge of the wind lip, indicating touchy conditions.

Avalanche Discussion

The Methow picked up between 6" and 10" of snow by Friday morning, and observers noted a natural, loose dry avalanche below steep rock features in the alpine. The new snow was observed to lack storm slab characteristics, but winds created more cohesive slabs near ridgeline terrain. 

While persistent slab avalanches have become unlikely, they're still on our minds in outlying parts of the zone west of Washington Pass and more recently in the eastern mountains. On Wednesday 2/17, an observation from the Twisp River drainage in the near treeline band found the mid-January facet/crust combo unreactive in snowpack tests and over 3 ft down.  Buried surface hoar slightly closer to the surface,  less than 3' or 80 cm down, showed sudden results in snowpack tests. No new or recent avalanches down to this layer or other signs of instability like whumpfing, or collapsing were noted.  Further west, the last persistent slab avalanche occurred near Rainy Pass on Feb 8th (see photo below). It is suspected to have run on the mid-January crust-facet layer about 2-3ft below the snow surface. 

An atmospheric river looks to slowly enter the region on Sunday, along with rising temperatures, winds, and precipitation turning to rain at low elevations. With warming temperatures, heavy snowfall and strong winds, we can say conditions are expected to become quite a bit more dangerous on Sunday. If you get out on Saturday, help contribute to the forecast by submitting an observation!

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources. Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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