Officials from Olympic National Park knew some sort of wind event was the culprit, but nearby weather stations reported only light breezes that night. Radar didn’t show any storms.

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It came in the night, snapping trees like chopsticks.

Early on Jan. 27, more than 100 gigantic old-growth trees fell on the north shore of Lake Quinault.

The resulting thud at about 1:30 a.m. was strong enough to register as a small earthquake, according to a seismic monitor at Quinault.

Fallen trees, their splintered trunks left pointing in the air, blocked North Shore Road and damaged utility lines along a 1,000-foot stretch. The sides of the blowdown area were about a half-mile long.

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Officials from Olympic National Park knew some sort of wind event was the culprit, but nearby weather stations reported only light breezes that night. Radar didn’t show any storms.

University of Washington climatologist Cliff Mass investigated.

The fallen trees in the affected area near July Creek all faced south. The wind had to come from the north.

Theories abounded on the park’s Facebook page: Experimental military equipment, tornado, Sasquatch.

Mass checked for space objects reaching the ground but could find no evidence of one.

He did find evidence for something called, “a rotor circulation associated with a strong mountain lee wave.”

Mass said he can’t be certain. but he thinks an offshore front approached the blowdown site from the south. Lake Quinault sits in a valley between two ridges.

Warm air moved above cool surface air. Different wind directions, dropping pressure and other factors led winds to reverse direction in a rotor wave between the two ridges.

Wrote Mass, “An approaching front produced just the right conditions to produce a high amplitude mountain wave on the upstream ridge, which resulted in a strong rotor that produced powerful reverse flow (northerlies).”

Mystery solved. Maybe.