Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

It's time to take a big step back and plan to keep your slope angles shallow. Expect dangerous conditions, and we may be on the tail end of a natural avalanche cycle with a heavy dump of new snow, warm temperatures, and strong winds. You could trigger large avalanches at all elevations, so be confident of your ability to navigate around avalanche terrain if you venture into the mountains. 

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1.5–2.5

    We should end up with well over a foot of new snow at mid and upper elevations by Tuesday afternoon. In some areas the new snow may bond well, and in others it probably won't. Be especially careful on any upper elevation terrain facing northwest to northeast. This is where old snow is weakest; Where faceted grains rest above a crust from early March. The variable nature of faceted grains over a crust from early March should make for tricky conditions, where some slopes avalanche but others don't. Strong winds ramping up in the afternoon could add to instabilities and create wind slab danger at ridgelines.

    Look for shooting cracks, and signs of recent avalanche activity. If you find any of these, or if you find weaker snow over a crust beneath the storm snow, don't trust steep slopes. Be sure to regroup well away from any steep slope above, and keep you slope angles down below 30 degrees to stay safe.

    (3/14/2022) Tilt tests were good at showing the poor bonding with the early March crust and weaker snow above. Blocks slid off easily with ligh tapping. Photo: Matt Primomo

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    Wet new snow and warming temperatures during the daytime may cause yet another round of loose wet avalanches. This has been the pattern for the past couple of days, and we expect another round on Tuesday but they could be larger this time around. Look for wet sticky snow, rollerballs, and fresh fan-shaped avalanches to clue you into this avalanche problem. Avoid large steep slopes, and steer around consequential terrain once you observe these signs. 

    Example large, natural loose wet avalanche.

    Photo: Alpental Ski Patrol

Avalanche Discussion

A band of heavy rain and snow is pointed at the region, basically stationary as I type this. There could be a natural avalanche cycle at upper elevations tonight into early tomorrow (Monday eve/Tuesday AM). A fairly widespread loose wet avalanche cycle occurred on Monday afternoon with the new snow sliding easily on recent crusts as the temperatures warmed up. We've been tracking a layer of faceted grains just above a crust from early March, and tonight's storm will be the biggest 'load' that it has seen. Whether or not upper elevation slopes avalanche naturally, they're likely going to remain capable of producing large avalanches through the day on Tuesday. This is a good time step back, and plan tours that avoid avalanche terrain. Check for soft, weak, sugary snow over a thicker crust. A stout crust formed during the last atmospheric river event on March 1st. The snow that sat around above it became weak and faceted, and were buried on the 8th. You can find this weak layer structure on many shaded slopes. Below 5,000ft the facets have become moist and this layer may not pose an issue moving forward. Above that, the weak snow may persist, with dangerous avalanche conditions likely to continue well beyond this storm, especially in alpine terrain.

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