Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

A brief storm will bring strong westerly wind and a trace of snow. You may still be able to trigger avalanches in the recent snow, especially where winds form drifts at upper elevations. Clouds may break enough to cause some small wet avalanches on steep, sunny slopes.

Avalanche problems

  • Wind Slabs

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

    Strong westerly winds may form fresh slabs on Wednesday. Watch for cracking in the snow and small test slopes that slide easily as indicators of instability. Actively blowing snow will point out loaded slopes and fresh driftings. Steer around pillow and deeper drifts on steep wind-loaded slopes. Above treeline, avalanches could be bigger and easier to trigger. While unlikely, a similar wind event last week resulted in a couple of very large, natural avalanches above treeline (see photo and Discussion below).

    (3/11/2023)

    Crown of a very large avalanche in the Icicle Creek Drainage. We have a lot of uncertainty surrounding this avalanche problem. But best to make conservative choices in alpine terrain.

    Photo: Matt Primomo

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Wet avalanches could occur naturally as the snow surface becomes moist. After a cloudy start, clearing will allow the sun to warm the snow surface. Watch for roller balls and snow falling from trees as indicators that the snow is getting moist and weak. Moist snow surfaces and wet snow that slides easily are also good indicators that you could trigger an avalanche. Watch for natural avalanches coming from overhead slopes and hazards like falling tree bombs and cornices. You'll want to exercise caution near terrain traps like above cliff bands or tight gullies where a slide could push you into hazards. 

    (3/13/2023)

    Debris from a very large natural avalanche that occurred 3/13 in Tumwater Canyon, between Fall ck and Cabin ck.

    Photo: Matt Primomo

Avalanche Discussion

Avalanche professionals at Holden Mine reported natural avalanches during the storm on Monday (including seeing powder clouds from avalanches) along with a few small loose wet avalanches on Tuesday. Storm totals on Monday showed a large spread with the most snow falling in the northwest portion of the zone near Trinity and Holden (nearly 1ft with 0.9" of water). Weather stations in the Salmon la Sac area picked 6-8" and the Wenatchee Mountains received 2". The stormy weather and poor visibility prevented extensive observations. A very large, natural avalanche ran in Tumwater Canyon between Cabin ck and Fall ck (see photo above).The recent snow has piled deep over a couple of intermittent sun crusts and a pair of rain crusts from Valentine's Day, which can be found 3-5ft deep. Very large avalanches that occurred on the 10th on Cannon Mountain and Rock Mountain may have run on these crusts (or some other deep layer).  The Valentine's crust often presents as a crust/facet/crust sandwich, with weaker snow beneath the upper crust. Observations indicate wide variability in the structure and depth of this layer throughout the zone.

Regions covered