Lawinenlagebericht

East Slopes South

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

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

Kernpunkte

You're still likely to trigger avalanches at upper elevations where the winds drifted the recent snow into deep drifts. These stiff slabs formed over weak snow surfaces and could be quite reactive. It's nice to see cold temperatures and fresh snow, but give the snowpack additional time to adjust and avoid steep terrain below ridgelines and gullies where these slabs tend to form.

Lawinenprobleme

  • Wind Slabs

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

    On Thursday, riders in the Ahtanum Meadows area near Darland Moutain triggered two wind slab avalanches. Thankfully, the avalanches were small, and no one was caught, carried, or injured. These slabs formed over weak snow surfaces and can take longer than average to heal. To avoid triggering a wind slab, stick to slopes less than 30 degrees or travel on scoured ridgelines or slopes at mid and upper elevations. If you see cracks shooting away from you, the snowpack feels hollow or collapses beneath you, the snow is unstable, and you should steer clear of steep terrain. 

    Steep slopes below corniced ridgelines are a prime location for wind slabs. In addition, easterly winds formed slabs in unusual patterns, and you're also likely to find significant drifting mid-slope with slabs on steep convexities and cross-loaded gullies. Use visual clues like textured surfaces, cornices, and drifts around rocks and trees to point you to likely wind slab locations. 

    (2/15/2024)

    These drifts are good clues that wind slabs are present in the area, even at lower elevations. 

    Photo: Katie Warren

Avalanche Discussion

A welcomed 7-12 inches of new snow fell in the East South Zone at cold temperatures over Wednesday night and Thursday. Even the light to moderate easterly winds easily drifted the light snow around, forming wind slabs and textured surfaces. Friday should bring a break in the precipitation and wind before a small storm starts knocking on our door in the afternoon. We may see some sunshine during the weather break, particularly further north in the zone. The cold temperatures will likely keep most wet loose avalanche problems minimal, but you may see some dry loose avalanches release or snow start to shed off trees. 

On Thursday, an NWAC forecaster out in Ahtanum Meadows found a shallow and weak snowpack. Weak, faceted snow is associated with the Early February Crust and a sun crust on southerlies buried on Feb 11th. The low-density snow didn't have much slab structure in sheltered locations. Still, wind slabs were sensitive, and stability could deteriorate as the new snow settles with sunshine and warming. So, if you begin to see the surface snow moisten or stop punching through the new snow to the crust, storm slab avalanches in sheltered terrain might become a more prevalent problem. Since the new snow fell over these persistent weak layers, avalanches could fracture wider than expected. Earlier in the month, a prolonged period of warm temperatures and rain formed what we are calling the Early February Crust. A few inches of snow fell over the EFC, surface hoar and faceted grains formed on northerly aspects, and southerly slopes formed a sun crust. Weak snow exists above the EFC and below the Feb 11th sun crust. The surface hoar is buried below 1-2ft of new snow. The snowpack is thin and weak, and these persistent weak layers may become a prolonged problem.

Expect very thin (or even non-existent) snowpacks at lower elevations and on some steep southerly slopes. Unfortunately, we're still talking about travel hazards. Slick crusts, exposed obstacles, open creeks, and bare ground continue to make travel more adventurous. While this storm was a welcome refresh, it's probably still best to use established roads and groomed trails for better access to the high country. 

Abgedeckte Regionen