Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

You could trigger avalanches in wind-drifted snow near ridgelines. Avalanches may be larger and easier to trigger in the Salmon La Sac area, where significantly more snow accumulated over the past 24 hours. Steer around steep slopes with deep pillow-like drifts. Saturday will be the opener for a more significant storm overnight, so expect increasing danger in the late afternoon hours. 

Avalanche problems

  • Wind Slabs

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

    You could trigger lingering wind slabs from Thursday night or freshly formed wind slabs from southerly winds on Saturday. But the newly formed slabs are likely more sensitive and easier to trigger. Look for actively blowing snow, drifts, and cornice formations to point you toward wind-loaded areas. If you observe shooting cracks or the snow feels stiff and hollow, simply steer around steep terrain to avoid triggering an avalanche. Even a small avalanche could be a rough ride over exposed rocks and other hazards. While most avalanches likely won't be large, a puget sound convergence zone brought significantly higher snow totals to Salmon La Sac. You could find 8-10 inches of snow with wind slabs well over 1 ft deep. So be prepared for locally higher danger in this western area of the zone, particularly at the upper elevations. You may also find isolated areas where you could trigger a storm slab where you find much deeper storm snow totals. Use small test slopes or quick hand pits to observe how easily the new snow slides on the old snow surface. Snow that slides easily or a test slope that produces a mini avalanche means you could be more likely to trigger a larger and more consequential avalanche in bigger terrain.

    (4/8/2023)

    Here is an example of a small wind slab that you may encounter on Friday. Notice the cornices pointing to the direction of wind-loaded slopes. 

    Photo: Mission Ridge Ski Patrol

Avalanche Discussion

With the last rain event behind us, a smaller but significant atmospheric river will impact the Cascades late Saturday into Sunday. The east slopes of the Cascades may see over 1' of new snow, with the highest snow totals near the Cascade Crest. Thankfully, we put the saturated snowpack in the freezer on Thursday night, with temperatures well below freezing at all but the lowest elevation weather stations. While we don't know the full impacts of the prolonged rain event on the snowpack yet, especially at upper elevations, there's a good chance that the November weak layers changed to meltforms on most slopes. We know that all but the highest peaks now have a stout melt-freeze crust on the surface. Mission Ridge Patrol reported the crust to be nearly 8" thick. While this next round of snow will fall on a much stronger snowpack base, we must wait to see how well it bonds to the newly formed crust. 

Unfortunately, with last week's rain and warm temperatures, many areas lost over 50% of their snowpack. Lower elevations have a lot of exposed bare ground, so depending on where you go, the chance to hit buried rocks, logs, and other obstacles may still be a significant hazard. The refrozen snowpack may also make travel challenging, so ensure you have suitable equipment, such as scratchers on your snowmobile, crampons, or ice axes to travel on steep icy slopes.

We still have minimal information from the upper elevations, so if you venture high into the mountains, be prepared to assess the snowpack conditions you travel. Step into larger terrain slowly and look for red flag signs of instability, such as blowing snow, collapses, or shooting cracks. 

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