Avalanche Forecast

Issued: Dec 23rd, 2019 10:00AM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold.

Northwest Avalanche Center NWAC, Northwest Avalanche Center

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The avalanche danger has trended down since the weekend but sensitive weak layers under the recent storm snow may persist at high elevations. If you feel collapses, hear whumpfing or see direct signs of instability, use caution on terrain connected to slopes steep enough to slide. Watch for low snow coverage and ground hazards at low and mid elevations.

Summary

Discussion

We received a public observation of a snowmobile triggered slab avalanche SE of Darland Mt on a NE aspect around 6600’ (photo below). The avalanche was triggered on Saturday afternoon. No one was buried or injured. Snow depths averaged around 4 ft. in this area.

Recent storm snow instabilities at upper elevations should be healing over time with the avalanche danger trending down overall. However, persistent weak layers can remain sensitive to human triggering well after a storm. Without more direct evidence, you’ll have to tread carefully in terrain connected to slopes steep enough to slide. Persistent slab avalanches can break in surprising ways and can be triggered remotely or from low angled slopes.

This observation also helps us paint a picture of the rain/snow-line following the recent atmospheric river event. Rain likely reached at least 6000’ for much of the zone with remote weather stations showing a decrease in total snow depths due to a sustained period of rain and above freezing temperatures on the back end of the multi-day event.  

At low and mid elevations, exposed or shallowly buried ground hazards, like rocks, stumps, and creeks can amplify the consequences of even a small avalanche.

If you travel to the East South backcountry, please submit an observation.

Forecast Schedule and No Rating definition

At this time, we do not have enough specific snowpack information to issue an avalanche hazard rating for the East 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.

Snowpack Discussion

New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.

 

Valid until: Dec 24th, 2019 10:00AM