Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Thick slabs are becoming less likely to trigger, but remain mindful of the type of terrain you enter, especially further east in the zone where the snowpack is more shallow. Consider steering around very steep or unsupported slopes, as a problematic snowpack structure remains in place. Tuesday will be a great day to track snow surfaces ahead of another snowy pattern.

Avalanche problems

  • Persistent Slabs

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

    Persistent slabs are trending less and less likely, but we call them persistent for a reason. It may take a larger load like a snowmobile, or cornice drop to initiate them now, or a group of people standing in the wrong location. Any slide triggered would be surprising, and they can break widely across terrain features. Red flag signs of danger like shooting cracks and whumphing collapses are less likely to occur as we get further from last week's storm, but the problematic snowpack structure remains.

    We recommend using safe travel protocol if you do decide to venture into steeper terrain. Only expose a person at a time to avalanche terrain. Stop and regroup in safer areas, well away from and well away from potential runout zones of larger slopes. 

    A weak crust/facet combination can be found 2-3ft below the surface. The further east you are from Washington Pass and the Cascade crest, the weaker and shallower the snowpack is. Observers have reported whumphing collapses and other signs of these avalanches on Delancey Ridge. On the 9th, many natural avalanches likely ran on old weak layers near Cutthroat Lake (see photo). We believe these locations make up the western boundary of this problem. 

    (1/12/2024)

    Natural avalanches on Tamarack Peak, near Harts Pass. These likely occurred Jan 11th with northwest winds. We don't know exactly which layer these avalanches ran on, but they look suspiciously like persistent slab avalanches. E-SE, 7200ft

    Photo: NCH

Avalanche Discussion

Expect a mostly cloudy, pre-frontal day on Tuesday. Winds may just begin to ramp up at ridgelines late in the day. Temperatures have been slowly 'warming' after bottoming out at -28 on Saturday. You'll find a range of conditions with mostly soft, settled powder in sheltered areas and varying degrees of wind affect on open, exposed terrain. What's on the surface is likely to be weak and faceted. If you make it out, it'll be a good time to track and document what you find ahead of a prolonged snowfall event that should begin Tuesday night. The brunt of the snowfall comes on Wednesday. 

Storm totals between January 8th and the 12th are around 2 feet for much of the zone. On the 12th, an NWAC observer found some recent wind slab avalanches, one of which may have stepped down to a weaker layer near Goat Peak. That same day an observer reported a collapse while skinning uphill on a supported feature of Delancey Ridge. On the 11th, multiple parties reported triggering small avalanches in recent storm snow and fresh drifts. Late in the day and overnight, natural avalanches ran due to northwest winds. Some of these may have stepped down to deeper weak layers, especially near Harts Pass and east. On the 10th, observers reported several large, natural avalanches over 2 feet deep near Cutthroat Lake (NE, ~6,800ft) that may have run on a crust from December 30th. That same day, observers on Delancey Ridge reported over 20 rolling collapses at all elevations on a similar crust/weak layer that developed during the prolonged dry periods in December. 

You may find up to 6 feet of snow on the ground at upper elevations near Washington Pass, with half that much in the mountains near Mazama. There are several decomposing crusts and layers of sugary facets that developed throughout December. In some locations, these layers present as individual layers; in others, they all meld together. Near and west of the Cascade crest the snowpack is deeper, has less weak layers, and the crusts are typically thicker and more stout.

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

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