Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

Avoid all avalanche terrain and stay well out from under slopes steeper than 30 degrees. Warming temperatures and rain on a weak snowpack will create very dangerous conditions. Wet avalanches could be very large and destructive and run into lower elevations from overhead terrain. Cornice falls and avalanches on wind-loaded slopes could initiate much larger and more deadly slab avalanches. 

Avalanche problems

  • Wind Slabs

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

    Windward, loaded slopes steeper than 35 degrees will be very dangerous. Cornices will be building and could easily fall as temperatures warm during the day. Use extra caution near cornices while traveling on ridges, and make sure to give them plenty of space. There have been multiple reports of recent cornice falls during the last warm-up, including some that triggered deep avalanches. Avoid wind-loaded slopes, as you'll have an increased chance of triggering any avalanche there. Consider that triggering a cornice fall or a smaller wind slab avalanche could be enough to gouge into deeper layers, resulting in a very dangerous slide.

    The general wind direction will be southwest, and snow will fall above 5,500ft through the night. As temperatures warm through the day, you may see these wind-loaded slopes and cornices run naturally. 

    (1/26/2024)

    Wind-sculpted features at upper elevations in the Blue Lake basin.

    Photo: Will Govus

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–3

    Choose well-supported and low-angle terrain in dense forest and well away from the runouts of avalanche paths. Avoid traveling on top of any features that you suspect might have cornices. We anticipate cornice fall-initiated avalanches. Wet slabs and moist persistent slab avalanches could break widely across the terrain and run 3 feet deep. The ongoing warm-up and rain will make them easier to trigger and could bring widespread natural avalanches up to size D3. At lower elevations, wet loose avalanches will be widespread and could grow large. In the eastern foothills and mountains east of Mazama, wet avalanches could involve the entire snowpack.

    Rain and warming temperatures will weaken the existing snowpack structure. There are two problematic weak layers: small facets buried on or around January 8th in the top 1/2 of the snowpack and a series of crusts and large weak grains from December in the lower 1/3rd of the snowpack. These layers were reactivated by an intense storm on January 17th and a warm-up on the 20th. Observers reported cornice-triggered, human-triggered, and natural avalanches on the 25th, 26th, and 27th respectively.

    (1/25/2024)

    A recent natural avalanche (D1.5) likely ran on an older weak layer and may have been initiated by cornice fall. Poster/Pika Pk NE, 7,2000ft

    Photo: North Cascades Mountain Guides

Avalanche Discussion

On Saturday, observers on Kangaroo Ridge reported a large collapse on the January 8th facets and audible natural avalanches in nearby terrain. On Friday, observers remotely triggered a very large persistent slab avalanche on an east aspect at 6,000ft in Leap Creek. Riders also triggered a small wind slab avalanche in Liberty Bowl near Blue Lake. An NWAC forecaster near Varden Creek (NNE, 5,400ft) found propagating test results on the early January facets in the middle of a shallow snowpack (65cm with HS 117cm). On Thursday, a recent natural avalanche was reported from the Hairpin Valley on Poster/Pika Peak, NE, 7,200ft. Observers believe the avalanche may have been initiated by a cornice fall and ran on the early January weak layer in the top 1/3 of the snowpack (50cm below the surface with HS 150cm).

On the 24th, NWAC forecasters traveled near Blue Lake. At a profile site (NW, 6,650ft), they found propagating test results on the January 8th facets ↓65cm and sudden collapse failures on old facets and crusts from December. The structure of older, stiff slabs over the thin, weak layer of January 8th facets, ~2 feet below the surface, matches a profile near the Poster Peak avalanche. On the 23rd, a forecaster reported a number of small, loose dry and wet avalanches in very steep, craggy terrain. Warming temperatures moistened snow surfaces up to about 6,000ft on all aspects. 

Other recent observations pertinent to persistent slabs are: 

  • Another large cornice-triggered avalanche in Cutthroat drainage ran on a deeper weak layer, likely occurring on the 21st. Deeper crowns were spotted since the January 16th storm, though visibility was poor.
  • On the 21st, an observer in the Twisp River area found that the mid-December crust produced unstable propagation saw test results. They also experienced loud whumphs that shook trees as the collapse propagated widely across the terrain.
  • Observers reported a couple of older D2.5 avalanches that ran on deeper weak layers near Hart's Pass, likely around the storm of Jan 17th. These occurred on an east aspect at 7,000ft and a west aspect at 5,800ft.

If you're in the mountains, please let us know what you find.

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