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

Issued: 6:20 PM PST Saturday, December 30, 2017
by Kenny Kramer

Look for signs of recently wind transported snow such as uneven snow surfaces, fresh cornices, and snow drifts. Identify and avoid areas where wind loaded slopes exist. Recent strong winds may have loaded slopes well below ridgeline.

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Avalanche Problems for Sunday

Wind Slabi

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Forecast for Sunday:

Expect Sunday’s clearing and mild weather to allow the snowpack time to gain strength.

Newly formed wind slabs will continue to be a problem into Sunday. Look for areas of recently wind transported snow such as fresh cornices, snow drifts, and uneven snow surfaces. Identify and avoid locations where recent wind loading has occurred. Strong ridge top winds may have loaded slopes well below ridgeline. While we expect wind slabs to primarily exist near and above treeline, keep a watchful eye out for exposed terrain features below treeline where wind slabs may have formed.

Wind slabs can be deceptively difficult to manage in the terrain. Take a moment and read our recent blog post by NWAC Pro Observer Jeremy Allyn on wind slabs.

Warming temps and sunny skies may allow for small loose wet avalanche to occur on steep sun exposed terrain late in the day. Be mindful of steep sunny slopes, especially near rocks where these loose avalanches are most likely to occur.

Despite all this new snow, early season hazards still exist. Many creek beds have still not filled in for the winter.

Avalanche Summary:

Saturday afternoon brought  to a close a very active storm pattern which began Thursday.

Several inches of new snow from Saturday now sits above a rain crust formed during Friday’s warmer weather. Strong winds Friday night and Saturday morning redistributed much of the recent snow, leaving behind a variable snow surface. Soft storm snow, breakable crust, and stiff wind slabs can all be found in the backcountry.

Below the 12/30 rain crust a generally strengthening snowpack can be found. Weather stations from across the region confirm the upper snowpack is settling and observations demonstrate that it is gaining strength.



On Saturday Mt Baker Pro Patrol reported wind transportation of the new snow at the upper elevations forming small shallow slabs. Evidence of rain was found to the top of the ski area and a natural loose wet avalanche cycle occurred in the surrounding backcountry overnight Friday, likely during the rain event.

NWAC pro observer Lee Lazzara on Bear Paw Mountain Saturday. Lee reported a variety of snow surfaces conditions due to recent wind transportation of snow. He observed wind slabs up to 2 ft thick sitting on a firm rain crust formed during the overnight rain event. Snowpack test produced highly variable results in the upper snowpack, however no observations indicated significant layers of concern. 


On Saturday NWAC Pro Observer Jeremy Allyn was in the Crystal backcountry. He observed evidence of rain in the form of a breakable rain crust all the way to ridge crest. Recent winds had redistributed the overnight snow forming pockets of wind slabs on lee slopes. Jeremy noted that variable snow surface conditions exist due to the recent wind event.

No Corresponding Mountain Weather Forecast Available