Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

There is an increased chance of seeing, triggering, or being overrun by wet avalanches on southerly aspects. Rollerballs, pinwheels, and wet, mushy snow mean it's time to put some space between you and steep, sunny slopes overhead. Keep an eye on what is going on in the terrain above you.

 

Avalanche problems

  • Loose Wet

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

    With full sun forecast, the question isn’t “Will we see wet loose avalanches?” it’s “How many and how big?” The 1-2’ of recent new snow saw some sun on Monday, but Tuesday should take it up a notch. The sun should primarily affect southerly slopes but will start to work its way onto due east and west aspects as we creep into the second half of February.

    If you start seeing numerous and/or large wet avalanches, assume the danger is a whole step higher where you are - and put even more distance between yourself and steep slopes in the sun.

    (4/13/2021)

    Wet loose avalanches usually start at a single point and entrain more wet snow as they slide down the mountain.  While most are small some can grow quite large.

    Photo: Andrew Kiefer

  • Storm Slabs

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

    Slab avalanches are not the primary problem but should still be on your radar, especially if heading to upper elevations that saw more snow and wind loading in the last storm. Reported slab avalanche activity has been limited. On the other hand, observations are also limited other than in well-traveled, mid-elevation terrain like the Baker BC. There is a big difference between knowing what is out there versus just thinking you know what is out there. 

    Unsupported features like steep, convex rollovers are where you will most likely trigger a slab avalanche. Hand shears and test slopes can help you gauge the bond of new snow layers above the stout crust. Whatever you do, don’t rush into steep unsupported slopes at upper elevations, especially those with any sort of consequence in the terrain below.

    (2/14/2023) 

    Really steep, unsupported terrain is where you might still trigger a slab avalanche.

    Photo: Guided Exposure

Avalanche Discussion

Wet loose avalanches were the main observation today in West North and Stevens Pass, but for slightly different reasons. To the north, they were observed as triggered purely by the sun with a few on the south side of Herman in the Baker Backcountry and more initiating in steep alpine terrain on the southwest flanks of Sefrit.

Natural and human-triggered wet avalanches in Stevens Pass were more widespread and occurred on all aspects due to a combination of warm temperatures, light rain, and solar greenhousing. No new slab avalanches were reported and no observations were submitted from West Central so we don't know exactly where this zone fits in between it neighbors.

Observers at mid-elevations in West North have found that the storm layers are bonding well, and faceted snow below the new snow doesn’t seem to be an issue. Strong over weak layers are still found in the storm snow but haven’t yielded clean shears. Faceted layers saw lots of warmth and rounded to the point that they didn’t propagate a fracture in stability tests. Upper elevations are still a question mark.

Be ready for a shift to cooler, potentially windier weather on Wednesday with north and east winds. This pattern doesn’t usually create a big jump in avalanche danger but does shift the problem area to less common aspects. Be ready to see fresh wind slabs on west and south aspects in the second half of the week.

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