Avalanche Forecast

Snow and Avalanche Discussion

All of February into mid-march featured below-normal temperatures. A sudden shift in the weather pattern has brought 6 days of above-freezing temperatures at 5,000 ft. The upper snowpack has warmed quickly, but cold layers remain not far under the surface. The snowpack is not expected to be handling the rapid changes gracefully. Warm temperatures and sun are the main drivers of our avalanche concerns. Keep typical spring concerns on your mind, including wet snow, cornice falls, and timing your travel with progressively warming snow surfaces.

In the adjacent Central East zone, observers reported wet loose avalanches the past few days on a variety of slopes, some big enough to bury or kill a person. A significant avalanche cycle occurred in Tumwater canyon with avalanches on almost all aspects with avalanches running as recently as Sunday and closing Highway 2.

On Thursday, an observer reported a cycle of large slab avalanches (possibly occurring on the 12th) in Swakane Canyon on northerly aspects with shallow snow cover. These avalanches ran on the ground.

Avalanche Problems:

For loose wet avalanches, monitor changes in the upper snowpack, looking for natural pinwheels or small loose wet avalanches as clear signs of increasing danger. As the loose wet hazard increases, change your aspect and avoid similar slopes.

Wet slab avalanches are a different story. You may not see direct signs of instability prior to a wet slab release. As the day progresses, deal with the uncertainty surrounding this dangerous and hard to predict avalanche problem by avoiding terrain where avalanches can start, and limit your exposure to where avalanches can run or stop. With each passing day of melt, more water enters the snowpack and these avalanches will become increasingly destructive.

If you find yourself in an area that appears to have a weak and shallow snowpack, stick to well-supported slopes and avoid areas of wet, unsupportive snow. You can check how deep water is traveling through the snowpack by digging and looking for moist layers of snow.

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.

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