Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Default toward more conservative terrain to reduce the chance of triggering a low-likelihood but high-consequence slab avalanche. You could still find accumulations of fresh, wind-deposited snow at higher elevations. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    2–2.5

    There is still a chance of triggering a large slab avalanche that releases in a layer of weak faceted snow 2-4’ below the surface. The likelihood will increase in areas where there is renewed loading in the form of wind transported snow. There might even be a natural avalanche or two if wind speeds are stronger than forecast. 

    No human-triggered slab avalanches were reported in the last week despite lots of traffic in a variety of avalanche terrain. On the other hand, observers in West North reported a collection of large natural avalanches that likely released during or immediately following fresh snowfall on Feb 5th or 6th. 

    If you were to trigger one it would be in a wind scoured area with less new snow over the weak layer, on an unsupported slope like a steep convex roll or above a cliff, or in less traveled, remote terrain.  A heavy load like multiple snowmobiles, large groups of people, or big cliff drops might trigger an avalanche where the load of a single person or sled would not. 

    (2/9/2025)

    This slew of natural avalanches in the West Fork of Swift Creek/West North were reported on Sunday. The time of occurrence and weak layer are hard to pin down. Whatever the details, it's proof the layering is still out there to produce slab avalanches. North aspect at 5500'.

    Photo: Andrew Richardson

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Strengthening outflow winds (i.e. northerly and easterly) should affect some areas of West Central. Wind speeds are generally light to moderate, but still strong enough to drift the plentiful light-density snow at the surface. Many areas will not see much of a wind speed increase and therefore no new wind slab formation. Stubborn or unreactive, older wind slabs might still be found.

    Actively drifting snow will show you which slopes are building fresh slabs. Track changes in snow texture and stiffness and you gain elevation and change aspects. Use simple tests like hand shears or small-slope cuts to check the bond of wind slabs to the layer below.

    (1/2/2025)

    Obvious signs of wind transport along this exposed ridge pointed toward potentially loaded slopes. 

    Photo: Dallas Glass

Avalanche Discussion

Loose, unconsolidated snow can still produce small avalanches, especially once it gets going in steep terrain with long sustained fall lines. Stay alert to snow moving with you downhill if descending or side-hilling steep slopes. Afternoon sunbreaks could get snow to shed from cliffs and trees which can trigger loose snow avalanches on slopes below.

On average there's three or more feet of right-side-up snow over the old snow surface buried on January 30th. This snow sits directly on crust in terrain that saw strong sun and warming from January 26th through 29th. On more shaded slopes, the new-ish snow lies over a layer of faceted snow over a crust - now decomposing - that formed earlier in January.  More faceted snow is found below these crusts on all aspects. Avalanche activity related to these layers peaked last weekend. Snowpack testing still points towards propagation in layers of faceted snow. 

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