Lawinenlagebericht

East Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

Dangerous conditions are expected to develop for wind slab avalanches, take a big step back with your terrain selection on Thursday. Choose lower angled, and wind-sheltered terrain. A storm will bring some new snow and very strong winds to the zone.

Lawinenprobleme

  • Wind Slabs

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

    Strong wind and new snow should quickly form thick and reactive wind slabs in exposed terrain. Wind slabs will be made up of snow both new and old, and could be large at higher elevations. Expect that you could easily trigger wind slabs on the leeward sides of exposed features including ridges and mid-slope features. With very weak snow surfaces, slabs could be triggered from a distance or from below. 

    Look for signs of instability such as recent slab avalanches, shooting cracks and whumphing collapses. Avoid steep slopes if there's been drifting nearby or if you find signs of instability. In many areas of the zone the snowpack structure has some weaknesses near the ground. Slides have the potential to step down to deeper layers, and become much larger, scarier avalanches.

    (12/19/2021)

    A crown from an avalanche (size D2.5) that ran on 12/18. Similar avalanches may run on Thursday.

    Photo: Matt Primomo

Avalanche Discussion

Observers throughout the zone have noted weak snow surfaces due to the very cold temperatures of the past few days. The surface that will get covered up by new snow overnight into Thursday is likely to become a weak layer for avalanches for the next few days, at least. Plenty of loose snow exists that could easily get transported into slabs. Expect a cold, blustery day, with snowfall in the morning that lightens up later.

The storm snow from December has generally been settling out, although at it's base a weaker structure exists in many areas. An observation from the Icicle Creek drainage on the 28th showed that weaker snow has formed between deeply buried crusts from earlier in December. A very large avalanche was observed off of Mt Mastiff, on the eastern edge of the neighboring Steven’s Pass zone. A thin crust from the Solstice is now buried 20 to 30 inches in western parts of the zone and 5-10 inches in eastern areas. Cold temperatures have likely contributed to weakening of bonds between many crust interfaces. Above 6000ft, this crust may be difficult to discern or might not have formed at all. While we have minimal information on these deeper interfaces, it warrants caution and reason to take a large step back on Thursday. 

If you get out please post to our observation page, and help contribute to the forecast!

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