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East Slopes South - South of I-90 to Columbia River

Issued: 6:29 PM PST Sunday, February 10, 2019
by Robert Hahn

A series of cold winter storms with significant new snow and wind keeps elevating the avalanche danger in the East-South Zone. While we don’t know when the snowpack will reach a breaking point and we don’t have a lot of specifics for this area, we know that recent snow likely fell on a very weak snowpack and has created some dangerous avalanche conditions. This is a time to be extremely cautious and avoid all open slopes greater than 35 degrees. You may see avalanches even at lower elevations and in the sagebrush country further east of the mountains.

Danger Scalei
  • No Rating (Info Avail)
  • Low (1)
  • Moderate (2)
  • Considerable (3)
  • High (4)
  • Extreme (5)

Snow and Avalanche Discussion

The Cascades East-South zone is receiving significant and incremental loading of weak and likely faceted snow layers from a late January dry spell. A significant shot of snow and wind will impact this zone Sunday night with increasing snow and wind once again Monday afternoon. The snow that fell Friday through Sunday was so light, and the winds so strong that the weather stations may have done a poor job of measuring the water weight of this new snow. We suspect 8-10” of snow fell Friday into Saturday. We suspect the snowpack is highly variable and contains several weak, old snow layers. As the snowpack continues to grow, so have the potential size of any triggered avalanches. Some of the recent snow sits on recently exposed dirt or rocks. Due to the significant variability of the expected snow conditions and our limited knowledge of the snowpack, this is a time to be conservative as you travel. Stay off of open slopes greater than 35 degrees.

There are three things to key into as you travel Monday.

  1. Wind loaded slopes are suspected to be the most dangerous. Use visual clues such as snow drifts, fresh cornices, and uneven snow surfaces to find areas where the wind transported the snow. When you see these clues, avoid steep slopes nearby.

  2. If you see natural slab avalanches, experience sudden collapses, or see long shooting cracks, stay out of all nearby avalanche terrain, including where avalanches can run and stoop.

  3. Low elevation avalanches: The recent storms have brought snow that you can recreate in to lower elevations. These snowpacks also contain the same weak layers we are concerned about in nearby regions. Don’t think, just because you are out in lower hills, you are safe from avalanches.

Forecast Schedule and No Rating

At this time, we do not have enough specific snowpack information to issue an avalanche hazard rating for the East Slopes South zone. However, even when No Rating is applied, applicable avalanche conditions and backcountry travel advice will be provided throughout the season. When weather systems produce very dangerous avalanche conditions in adjacent zones, NWAC will issue an avalanche warning for this zone as well.

Regional Synopsis coming soon. 

No Corresponding Mountain Weather Forecast Available