East Slopes South

Dangerous avalanche conditions linger as this week-long storm reaches an interlude Wednesday. Windblown snow will continue to build slabs and maintain the possibility of large slabs that may have the potential to break deep into old layers of weak snow. In wind-sheltered areas, reactive new snow keeps the possibility of human-triggered avalanches in the forecast. Choose terrain below 35 degrees and avoid travel above creeks and cliffs. Limit your time traveling in areas with steep open slopes above you.

On Monday, observers in the Icicle drainage remotely triggered a large avalanche (about 1.5 feet deep)  from about 150 ft away on a S aspect at 6100 ft. The suspected failure likely involved weak snow buried at the beginning of the storm cycle on Feb 11th, but the failure layer has not been confirmed.

On February 8, a snow biker triggered an avalanche in the neighboring East Central zone and was buried and killed. For more details and information, see the Accident Reports page and the post-incident investigation video below.  Our condolences to family, friends and the local community following this tragic event.  

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Avalanches such as these (and others) in neighboring zones have us very concerned as we head into the late stages of a significant storm cycle with multiple weak snow layers in the upper and mid snowpack.

We are reaching the end of a week-long storm and avalanche cycle in the East South zone. We expect that a natural avalanche cycle occurred on Monday as temperatures warmed and heavy snow mixed with rain or freezing rain.  Snow continued to fall through Tuesday, and weak layers in the snowpack will take significant time to adjust to the new snow load. Dangerous conditions exist at upper elevations where moderate to strong winds continue to drift large amounts of snow to the breaking point. Natural avalanches will be less likely Wednesday, but human-triggered avalanches could break widely over terrain features. Throughout the terrain, persistent slab avalanches are primed for human trigger. They could run on a recently buried weak layer, or possibly involve deeper layers resulting in an unsurvivable and very large slide. The largest avalanches may start on leeward, wind-loaded slopes near and above treeline. Watch for blowing snow, wind-stiffened snow, drifts, and cracks shooting through the snow as signs of recent wind loading.

Continue to avoid all slopes steeper than 35 degrees. Make sure to put more than enough space between where you travel and anywhere that an avalanche could start or come down from above. Only stop and regroup well out from under and away from any avalanche path. Give wide berth to cornices which will have formed over wind-loaded slopes. Cornice can break and trigger an avalanche.

Up to 2.5ft of new snow has fallen in the zone since the 11th. On Monday, observers reported a natural avalanche at 5880ft on a west aspect near Bethal Ridge and small natural dry loose avalanches up to a foot deep at Rimrock. Previous snow surfaces are suspected to be a mix of weak, and perhaps faceted grain types. An observer at White Pass found widely propagating storm slabs that were acting in surprising ways (see below), as they failed over these weak snow surfaces.  A surface hoar layer proved reactive on Monday - see the Cascades EC zone forecast for additional details.

If you're out in East South, help improve this bulletin bysubmitting an observation. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.