Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

There will be plenty of new snow to be carried around by the wind on Thursday. Coupled with some afternoon sun breaks, it could be a dynamic day in the backcountry. Look for red flags that new snow is unstable, such as long shooting cracks from your equipment, audible collapsing, and recent natural or triggered slab avalanches. If you see small bits of snow rolling down on a sunny slope, a small wet snow avalanche could soon follow.

Avalanche problems

  • Wind Slabs

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

    Both new and old slabs are on the table for Thursday. Reactivity in wind-loaded snow was observed in the zone on Wednesday, and new snow will be added on before these older slabs have had a chance to completely heal. A large triggered slab will be running on a slick crust below. Smaller slabs could be running on mid-storm layers that took shape during the system. With moderate to strong winds forecasted, we expect most hazard to be relegated to wind-affected terrain, but be on the lookout for signs of storm slab instability in sheltered terrain.

    Wind slabs typically form just below ridgelines and on exposed convexities and gullies. Blowing snow, cornices, and fresh drifts will be the most helpful visual clues to look for.  Expect to find wind-transported snow on either side of any given ridgeline where you find these features. Pay attention to the feel of the snow underneath your equipment as well; a change to denser or uneven snow indicates the wind influenced that spot. Signs of storm slab instability are the same: cracking, collapsing, and recent slab avalanches.

    (3/12/2025)

    A small wind slab intentionally triggered on the north facing side of a ridge.

    Photo: Payton Schiff

  • Loose Wet

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

    The sun will poke through in the afternoon and rapidly influence new snow. While we expect moderate to strong winds will largely hold off a lot of warming, you can't bank on it this late into the year when the sun is high in the sky. The typical initiation of wet loose avalanches involves rollerballs and pinwheels or chunks of snow falling from cliffs and trees. If you're on a sunny slope and the snow is becoming sticky and moist, find lower angle or shadier slopes.

    (3/21/2021)

    Wet loose avalanches often initiate where snow sheds off rocks and trees onto the slope below. Note that there are both small rollerballs and wet loose avalanches in this image. 

    Photo: Zack McGill - Cascade Mtn Ascents

Avalanche Discussion

Diverging a bit from the norm, this storm system will impact the zone from east to west and likely deposit an equal amount of snow throughout. The timing of the storm is largely overnight, starting around 9 pm on Wednesday and coming to an end around 9 am on Thursday. Areas near the Cascade Crest may continue to see small showers throughout the day. Due to the nature of this storm, there could be big differences in the kind of precipitation particles falling - such as graupel for a period of time - which could create mid-storm layers. The wind will not subside with the snow. Expect to encounter blustery ridgelines and continued wind transport throughout the daylight hours. 

Avalanche professionals reported reactivity in the zone on Wednesday. Mission Ridge Ski Patrol saw lots of wind transport and very reactive 5-6" wind slabs sliding on a slick crust that formed earlier in the month. An NWAC Forecaster traveling in the Salmon La Sac drainage found slightly more stubborn 3-7" slabs, but the distribution was widespread. Many of these slabs were also sliding on a crust. She also noted that during an afternoon warm-up, the snow in sheltered terrain "slabbed up" a bit, and she was able to trigger a very small storm slab. You can read the full observation here. Without much of a reprieve before this next system, we expect these conditions reported on Wednesday to be elevated by Thursday morning.

Persistent slabs continue to be an issue in the adjacent zone to the north. While we’ve put this problem to bed in the East Central, it’s worth considering in very northern portions or more far-flung parts of the zone. To reduce your risk, you can default to simpler terrain that is planar and short.

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