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

Issued: 6:00 PM PST Sunday, December 31, 2017
by Kenny Kramer

Shallow stubborn wind slabs continue to linger in wind exposed terrain near and above treeline. Identify and avoid areas of recently wind loaded snow below ridge line and cross loaded terrain features.

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Avalanche Problems for Monday

Wind Slabi

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Forecast for Monday:

Continued mild weather New Year’s Day will continue to allow wind slabs time to stabilize.

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.

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.

Cornices along ridge crest in the west slopes and passes have grown quite large especially at higher elevations. Remember to give these features a wide berth. Cornices can break much farther back from the ridge than expected.

Photo: NWAC Forecaster Robert Hahn: A large cornice on Table Mountain in the MT Baker backcountry.

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:

Happy New Year from your friends at the Northwest Avalanche Center!

Mild weather on Sunday allowed lingering wind slabs to gain strength. Cool easterly flow brought clouds and lower temperatures to the Passes reducing the amount of stabilization in these areas.

Winds Saturday formed shallow slabs on a variety of aspects near and above treeline. Depending on elevation these wind slabs sit on soft snow storm snow or firm rain crust.

Reports from around the region snow rain and freezing rain crust well into the near treeline area. These firm crusts have capped storm snow which fell earlier during the storm cycle. Below the 12/30 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 and Sunday 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.

NWAC pro observer Lee Lazzara was 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.


Sunday Stevens Pass Patrol reported a freezing rain even to the top of the ski area Friday night. Winds Saturday formed shallow wind slabs within the area. Approximately 4” of soft snow sits above the freezing rain crust in wind sheltered areas.

Alpental Patrol Sunday reported a ½” freezing rain crust to the top of the ski area.


Sunday Crystal Mt Ski Patrol pockets of wind slabs at higher elevations. Friday’s rain curst extended to 6500’ in the ski area.

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 (6500’). 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