Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Cornices have begun to fail in random locations, the daily wet loose cycle is on, and a few very large slabs have been reported from the past couple of days. As the daytime temperatures ratchet upwards, expect increased chances for these isolated but consequential hazards. Give yourself plenty of extra room, well away from larger slopes and looming cornices in the chance one does release. 

Avalanche problems

  • Loose Wet

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

    With 4-6" of newer snow resting on a crust and warming temperatures, loose slides may run during the heat of the day as snow surfaces melt. Watch for roller balls and tree bombs as indicators that the snow is becoming moist. For the most part, these should be small, but in larger terrain they could entrain more snow than you'd want to mess with. Exercise caution near terrain traps like steep slopes above cliff bands and tight gullies.

    Example loose wet slides from the West South zone earlier this week.

    Photo: Andy Harrington

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–2.5

    Cornices have gotten quite large and have been failing in random locations over the past couple of days. Stay out from underneath overhanging cornices in the chance they might fall. A few isolated, but deep (up to 6ft deep) slabs have been observed over the past few days. While the chances of actually triggering one of these is probably slim, large loads like snowmobiles, big cornice failures, or perhaps a warming event could perhaps still do it. If any very large slides did occur, they would run much further than you might expect, so best to add in lots of buffer room well away from large steep slopes while your out in the mountains. Steep, large and unsupported slopes might be worth steering clear from once the daytime warming takes hold on Friday.

    You could still find a small, soft wind slab in upper elevation terrain with a recent round of easterly winds. Look for drifting patterns and textures, and feel for slightly stiffer snow as you gain elevation. Steer around drifts on steep and/or unsupported wind drifted features.

    (3/16/2023)

    Cornice fall over a recent skin track in Cutthroat drainage observed on Thursday morning.

    Photo: Ryan Minton

Avalanche Discussion

Three very large natural avalanches were reported on Thursday; A D3 on a NE aspect off Kangaroo into Willow Creek, a D2.5-3 in the Slot on a W aspect of Kangaroo, and a D3 from an E aspect in Cutthroat. Many of these ran beneath large rocky cliffs where storm snow deposited more deeply. The slide in Willow Crk appears to have run down to the ground on a moraine, with a crown estimated at 3-6ft deep. Last weekend, 2-4ft deep slabs were reported from areas such as Liberty Bowl near Blue Lake Col and in the Hairpin Valley. Significant snowfall and intermittent wind events since late February have added about 3ft to the snowpack, and now we're entering a warming trend.

The slow warming trend continues. Temperatures and sunshine should begin to have more and more of an affect on the snow and avalanche conditions over the next few days. 

The Valentine's crust is 3-5 feet below the surface in the western half of the zone, including near Washington Pass, the upper Silverstar drainage, and Hart's Pass. You can expect to find it closer to the surface at lower elevations and further east in the zone. There have been numerous observations and snowpack tests indicating weak snow and poor structure below this crust. If you're motivated to dig deep enough, you can probably still find the January 5th surface hoar. We have less of an understanding of the progression of these layers east of Mazama and the Twisp River drainage.  

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