Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

In the wake of an intense storm, you can still trigger avalanches. The most dangerous areas will be leeward sides of ridges where winds drifted deep slabs and where you find older weak layers under the new snow. For Friday, filtered sun and warm snowfall could be enough to trigger isolated natural avalanches in the recent snow. 

Avalanche problems

  • Storm Slabs

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

    Continue to limit your exposure to overhead cornice and large avalanche runouts. Use extra caution near slopes over 35 degrees. Avalanches in the new snow could take a variety of forms and sizes depending on where you travel. If the sun comes out or snow surfaces warm, isolated natural avalanches and cornices could fall from very steep, cliffy terrain.

    Strong winds drifted deeper slabs below cliffs and on leeward sides of ridges and wind-exposed features. Here, avalanches could easily be big enough to bury and kill you. In wind-sheltered areas, you may still be able to trigger storm slab avalanches within the recent snow. This is especially true where you find weak strong over weak layers of snow, and where there snow coverage was previously shallow.

    (12/19/2024)

    A very large, D3, natural avalanche that likely ran sometime on December 18th. It ran full-track, roughly 1,500ft vertical. Kangaroo Ridge, SW, 7,500ft

    Photo: Adam Butterfield

Avalanche Discussion

On shaded west through north through east aspects, there's a chance for very large avalanches to break widely and run on weak snow under the recent storm snow. Near Washington Pass, you may find weak layers adjacent to the December 7th crust, now 3 feet below the surface. At low elevations, east of Mazama, there's now enough snow for consequential avalanches. If you're traveling in these areas, watch for signs of instability like collapses and cracks. Wherever you travel, be ready to stick to slopes less than 35 degrees if you see signs of instability. 

A major storm impacted the region December 17-18th and brought significant snow including low-elevation terrain and the eastern mountains. On Thursday, an observer in the Hairpin Valley reported that the 12/17 storm interface was 75cm below the surface. He also observed a natural avalanche in the Cutthroat avalanche paths that occurred during the day. An observer in the eastern foothills reported a collapse. Temperatures stayed relatively cool and precipitation was mostly dry snow. Some warming of snow surfaces likely occurred west of Washington Pass and at low elevations.

On Wednesday, an observer in Mazama reported storm snow totals of 36" and wet loose avalanches. An observer on Blue Lake Peak reported numerous large to very large natural avalanches that ran Tuesday night, and they experienced whumpfing collapses. Observers near Frost Lake reported collapsing whumpfs and plumes of blowing snow on the ridge of Oval Mountain. Snow water storm totals from weather stations likely only tell part of the story. Rainy Pass: 3.4" SWE, WA Pass:  1.7" SWE Mazama 1.7" SWE. On Wednesday, few people were able to venture into the mountains. 

On the 15th, an NWAC forecaster went to upper elevations of Blue Lake Peak. On shaded slopes, the 12/7 crust was buried 10-16 inches deep and had weak, faceted snow on either side of it. Near Rainy Pass, the 12/7 crust is more robust, while it's thin and brittle on shaded slopes near and east of Washington Pass. 

You can contribute to the avalanche forecast. Please let us know what you see in the mountains by submitting an observation. 

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