Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

New snow and wind may create isolated and shallow wind slabs in some alpine terrain. Be mindful of large, unsupported and rocky slopes at upper elevation as deep persistent slabs could still be triggered with large loads in these areas. Firm and icy travel conditions may be found in many areas. 

Avalanche problems

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3

    Deep persistent slabs are largely dormant in the zone and we don't know of any activity since March 3 (West South Zone). However, the consequences of one of these avalanches could be high. The most suspect areas for a deep persistent slab are shallow, rocky and unsupported slopes. Features at higher elevation and with shaded aspects are the most likely for any of these. Steep, sunny slopes may be of less concern due to a thick melt-freeze crust near the surface.  A large cornice fall or a major warming event could be the trigger needed for a deep slab avalanche. Be intentional about where and how you travel with this snowpack structure in place. 

    Small and shallow wind slabs may build on higher elevation slopes with the addition of a few inches of new snow on Sunday night. Be aware of this possibility, and expect these slabs to be reactive as they sit over old snow surfaces. Steer around steeper, wind-loaded slopes if you find more than 4" or so of new snow and wind-thickened slabs.

    (3/10/2021) An older deep persistent slab in rocky and unsupported terrain. Northeast facing at around 6,500ft in Icicle Creek.

Avalanche Discussion

The mountains in the East Central may pick up 1-4" of new snow overnight on Sunday with more snow accumulating at higher elevations and near the crest. The new snow will be falling on well-developed crusts on east to west to south aspects and all aspects at lower elevation. On north-facing slopes at upper elevation, it will fall on weaker, near-surface faceted grains.  Stay aware of overhead hazards such as cornices, as they could fall. There have been observations from nearby zones of falling cornices in the past week. 

The last observation of a deep slab avalanche was March 1, however, the mid-January weak layer can still be found in many areas. There were reports on Thursday and Friday in the Icicle drainage that showed consistent results indicating propagation on north and southeast aspects near and below treeline. We currently have a wide range of conditions between mountains near the Cascade Crest and further east. The slab that sits over this weak layer ranges dramatically from around 8ft thick near the crest to less than 3ft in the eastern Wenatchee Mountains. 

Numerous deep and very wide avalanches (Many D3-3.5's, some size D4's)  ran between February 21st and March 1st in the mountains near the crest, and some deeper slabs were reported from the Wenatchee Range. In the northern end of the zone, near Holden, the mid-January weak layer doesn't appear to be a concern anymore.

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