Lawinenlagebericht

East Slopes North

Northwest Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Periods of strong winds will continue to move new snow through Saturday. Treat steep lee slopes below ridgelines at mid and upper elevations with caution. The new snow will layer over variable surfaces; surface crusts, older wind-stiffened snow and weak faceted surface snow. 

Lawinenprobleme

  • Wind Slabs

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

    Snow that began Friday afternoon should continue overnight and at times on Saturday.  New snow totals through Saturday should be in the 4-8+" range with the higher totals near Washington Pass.  SW ridgeline winds should be strong through Friday night and easily move the new snow at mid-and upper elevations. Look for blowing snow at higher elevations and if you find fresh pillow-like drifts, use caution on steep lee slopes below ridgelines where you could trigger a wind slab avalanche. 

    While the new snow will fall on a variety of surfaces, the most touchy areas may be where the new snow has built over weak surface facets. Visual clues like cornice lines may be less helpful than usual - we're switching from a period of notable northerly winds to our more traditional S-SW storm track.  Red flags like shooting cracks or natural avalanches are clear signs to step back to lower angled and more sheltered terrain. 

    Snow levels will stick around 3500-4500' over the next 24 hours.  You may encounter small wet loose avalanches or more likely rollerballs at mid-elevations that experience oscillating snow levels.  

    If you start seeing signs such as cracking and smaller wind drifted slabs breaking on test slopes,  shift to a more conservative plan and steer around wind loaded slopes. 

    Photo: Josh Hirshberg

Avalanche Discussion

We are exiting a period of quiet weather and lower avalanche hazard as we head into the weekend and likely even into early next week.  While no single storm looks like a doozy, we'll see how conditions and stability change as we incrementally load the snowpack over the coming days. NWAC observer Willie Webster was out in the Pasayten wilderness on Thursday and found a shallower snowpack vs the Washington Pass area but similar surface conditions, snowpack structures and generally low avalanche hazard. 

Prior to this pattern change, recent warm temperatures and sunshine on the 25th and 26th formed crusts formed on steep, sun-exposed slopes. On shaded slopes, the snow on the surface and directly above the MLK crust was beginning to facet and weaken. Some observers have reported propagating test results on this layer.  We've also been tracking a layer of buried surface hoar from January 5th. Near Washington Pass, it's around 2.5ft below the snow surface but shallowly buried in the easternmost portion of the zone. Snowpack tests indicate the potential for propagation above about 5,500ft or in eastern portions of the zone, where the overlying MLK crust is thin or not present. 

The snowpack near the eastern edge of the zone is more shallow, and you may find weak layers of snow more susceptible to triggering an avalanche. In the lower-elevation foothills, warm and wet conditions transformed previously weak, low-elevation snow into melt forms.  While we have little recent info here, we suspect weak layers are forming adjacent to crusts in the upper half of the snowpack.

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