East Slopes South

Very dangerous avalanche conditions should continue with avalanches up to 3ft deep. Only travel in the backcountry if you are confident in your ability to exposure to upper elevation slopes from which avalanches may run into below treeline terrain. Choose small, treed, or slopes less than 30 degrees to travel in near and below treeline.

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.

Where in the 6th day of a significant storm and avalanche cycle in the East South zone. We expect that a natural avalanche cycle occurred on Monday through Monday night as temperatures warmed and heavy snow mixed with rain or freezing rain.   Bumping ridge picked up 1.0" of snow water equivalent in the 24 hours ending at 4 PM Monday. That is a lot of water falling onto a weak snowpack, particularly when you factor in wind-loading. Moderate to heavy snowfall should gradually taper off as we head into the day on Tuesday, but weak layers in the snowpack will take significant time to adjust to the new snow load. Very dangerous conditions exist at upper elevations where moderate to strong winds continue to drift large amounts of snow to the breaking point. Expect natural avalanches continuing into the morning hours that 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 they could 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.

Avoid all slopes steeper than 30 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. Stay far away from cornices looming 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.