Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

Wind slabs may remain reactive through Tuesday in upper elevation and exposed terrain. Identify steep and unsupported slopes to avoid that appear to harbor wind textured or drifted snow. The chances for deep persistent slabs have decreased, but continue to consider their consequences as you travel. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Shallow wind slabs released naturally from alpine terrain in adjacent Stevens Pass on Sunday, and wind continued to drift snow into the day on Monday. Steer around obvious wind features like textured or drifted snow, and wind pillows. Shooting cracks or hollow-sounding snow are signs you could trigger an avalanche on similar slopes. Identify terrain such as steep and unsupported areas of slopes to avoid. Avoid steep slopes below cliff bands where spin drift may have formed thicker wind slabs. A wind slab avalanche could be enough to trigger a much larger deep slab avalanche in some terrain. 

    If there are sun breaks during the day, keep an eye out for moist, sticky snow and rollerballs. These are all good indicators that wet loose slides could happen on steep slopes of similar aspects.

    (3/8/2021) Wind textured snow with a recent, shallow wind slab in alpine terrain of White Pine Cirque. Northeast aspect at about 6,400ft.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3

    It's been over a week since the last known deep slab avalanche in the zone (March 1), but the snowpack structure to create them remains in place. Be intentional about where and how you travel, and be sure to discuss this with your partners. High, shaded slopes may be the most likely areas for one of these to release on Tuesday. If you flip through some of the photos in the media reel below, you'll see some of these monster avalanches have coursed thousands of feet, broken mature trees, and pushed through areas you might not normally think twice about stopping. Before venturing into big terrain features, ask yourself, what would a very large avalanche in this terrain look like?

    Cornices are large and sagging in some areas, keep on the lookout for these and stay well away from them. If cornices fall, they could trigger very large deep persistent slab avalanches.

    (3/1/2021) A very large avalanche (D3) was triggered by WSDOT highway forecasters on March 1st in a portion of the West Camp path on Rock Mtn. Adjacent sections of this avalanche path ran naturally on Feb 26th. Photo: WSDOT

Avalanche Discussion

Over the weekend, a cool, snow showery regime set up and it finished with strong westerly winds. Now we have at least a few inches of new, and often wind textured snow over old snow surfaces. Observers found reactive wind slabs 6-8" deep in the Wenatchee Mountains on Monday. I observed plenty of wind-textured snow in alpine terrain east of Stevens Pass from a distance as well. The last major storm cycle occurred February 25-26th with ~2" of water equivalent at the Cascade Crest and extreme winds. This came on the heels of an even bigger storm.  From Feb 20-23rd, a massive storm brought up to 6" of water equivalent to the mountains near the crest but much less to the Wenatchee Range further east. Numerous deep and very wide avalanches (Many D3-3.5's, some size D4's)  ran on, or around the 22nd in the mountains near the crest, and some deeper slabs were reported from the Wenatchee Range. Similar-sized avalanches continued earlier this week.

Last Wednesday, observers reported widespread very large avalanches in the Chiwaukum range and the Icicle drainage from the most recent cycle. While conditions may be less dangerous in parts of the Wenatchee Mountains, due to less recent snow, the same weak layers can be found and recent avalanches have been triggered on them. In the northern end of the zone, near Holden, the mid-January weak layer is present, though it has produced inconsistent test results and doesn't appear to be a concern anymore in that area. 

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