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

Keep an eye out for signs of wind transported snow such as fresh cornices, uneven snow surfaces, and wind drifts. Avoid areas of wind deposited snow, especially above treeline where more soft snow is available for transport.

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  • Extreme (5)

Avalanche Problems for Sunday

Wind Slabi

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Persistent Slabi

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Forecast for Sunday:

With mild weather prevailing, the snowpack will continue to adjust and gain strength. Watch for lingering wind slabs in exposed terrain, especially above treeline. Look for signs of wind transported snow such as uneven snow surfaces, fresh cornices, and snow drifts. Each of these observations are signs that the wind has redistributed snow in the area. Identify and avoid wind loaded terrain features.

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.

Lots of uncertainty still exists around the potential for a Persistent Slab problem. Observations on the 12/16 crust continue to demonstrate that there is potential for avalanche on this layer. Signs of instability on the 12/16 crust will be difficult to gather, but any resulting avalanche could be very consequential.  Avoid large terrain convexities on W-NW-N-NE slopes below ridgelines where the somewhat reactive 12/16 layer was found on Friday.

Despite all the new snow, early season hazards still exist at some lower elevation locales and especially around creek beds that are not filled in.

Avalanche Summary:

Several inches of new snow fell in the Olympics Friday night into Saturday morning. SW winds overnight redistributed the new snow in exposed terrain forming new shallow wind slabs. This new snow and fresh wind slabs sit atop a rain crust formed during Friday’s warm temperatures.

A surface crust from mid-December can still be found within the snowpack. 2-3 feet of snow now rest on the 12/16 crust.


NWAC pro observer, Matt Schonwald visited Hurricane Ridge on Friday, 12/29 and stressed that this is a different snowpack than the Cascades! He visited W-NW-N-NE aspects and found the 12/16 crust and 1-2 mm facets down 2.5 feet. Several PST tests, self-arrested, but propagated through most of the column along the 12/16 layer. This should indicate that a persistent slab layer could be triggered most likely on large convex slopes below the ridgelines. Matt also noted wind slab developing with weaker storm layers down about 6 inches in recent snow and at 10 inches at recent/old snow interface.

No Corresponding Mountain Weather Forecast Available