Lawinenlagebericht

East Slopes South

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Fri
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Your risk of triggering a shallow slab increases throughout the day with potentially touchy slabs forming below ridgelines on the northern half of the compass. Evaluate the snow above the recent crust before engaging with wind loaded slopes steeper than 35 degrees.  Rain on snow will destabilize any cold surface snow below treeline.

Lawinenprobleme

  • Wind Slabs

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

    Expect wind slabs to be forming on similar aspects to where you find better riding conditions on Thursday. With 2-3" of snow and winds remaining in the light to occasionally moderate range, slabs will be forming near and slightly below exposed ridgelines. However, where these slabs do form, we're expecting S winds to load the same colder snow interfaces on the N half of the compass that have weakened under the last few cold, clear nights. As a result, 3-4" of wind-drifted snow could entrain drier snow and knock you off your feet. Check the degree of lower-density snow you can entrain with an inconsequential test slope. The more entrainment, the larger the potential avalanche. If you see propagating cracks, actively blowing snow, or encounter firm over weak layering, steer around areas of actively or recently formed drifts.

    (3/5/2023)

    Example: Cracks in wind-stiffened snow are a sign of wind slab instability.

    Photo: Matt Primomo

  • Loose Wet

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

    We're expecting light rain to fall on the snowpack up to 4500 ft. In most cases, this rain will fall on crusts with the potential for minimal results. However, anywhere cold snow remains at the surface, expect rain to destabilize the surface snow rapidly. Small avalanches could initiate naturally or you could trigger them on slopes 35 degrees and steeper. 

    (1/13/2023)

    Example: Wet loose avalanches on a steep slope.

    Photo: Trevor Kostanich

Avalanche Discussion

NWAC forecasters in the White Pass backcountry near the border with the ES zone found 12" of cold, low-density snow above the 3/31 crust at 4500 ft. This suggests that areas near the western edge of the zone may have 6-12" of cold, dry snow lingering on shaded aspects.  Wet loose avalanches up to 5800 ft on the W face of Pinegrass Ridge (ES zone), suggesting crusts will have formed to at least 6000 ft on most other aspects by Thursday. Fringe areas of the zone with more preserved, cold snow will have more hazard on Thursday.

NWAC Forecasters and observers noted windy conditions and multiple triggered wind slabs near White Pass on Monday. By Thursday, these older slabs should be fairly unreactive, but you can see them in the photo gallery.

Lower trailheads are melting out, and bare patches exist on some groomed trails.

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