Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Fresh snow + strong sun = 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.

 

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    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

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    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

A handful of wet loose avalanches were reported today, with a few on the south side of Herman and more initiating in steep alpine terrain on the southwest flanks of Sefrit. Similar avalanche activity also likely occurred in other parts of the forecast zone. No new slab avalanches were reported. Expect a crust on southerly aspects in the morning.

Observers at mid-elevations 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 layering is still found in the storm snow but hasn’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 that usually come with the Fraser Outflow. 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.

Regioni coperte