Residents and visitors in Tillamook County took to social media on Monday with questions about a boom that shook homes along the coast from the areas of Netarts to Sandlake.

While some suspected an explosion or earthquake was responsible, the majority consensus was the sound and shaking were caused by military aircraft. The 142nd Fighter Wing of the Oregon Air National Guard is currently hosting training with FA-18F Super Hornets from the VFA-41 Squadron out of Naval Air Station Lemoore, California.

The jets are conducting dissimilar air combat training, executing realistic scenarios that use advanced aerial tactics to prepare for actual warfare. The training, considered essential to military readiness in support of the Portland Air National Guard Base’s national and state missions, was slated for Aug. 11-23.

Gordon’s Tillamook Weather Center, a popular local social media page run by Tillamook County Sheriff’s Office Lt. Gordon McCraw (who also serves as the county emergency manager), reported that callers began asking about sonic booms around 10 a.m. on Monday, Aug. 12.

McCraw later posted a refresher of an explanation he gave in June regarding sonic booms. He noted that the jets aren’t zooming and booming above Tillamook towns, rather they’re over the ocean just off the coast, adding that how far and fast sonic booms travel is affected by the atmosphere. He said when it’s warmer and wetter the sound travels more.

“Obviously, we are warmer and more muggy these days, and the winds are westerly, which helps the sound move inland further also,” McCraw said.

McCraw wrote that another influence could be temperature inversion, trapping the sound and bouncing it between surface and the inversion level. He said Tillamook County generally has an inversion layer in the morning hours.

“Normally, temperature decreases with height. An inversion is an area where the temperature temporarily rises with height,” McCraw wrote. “Watch the smoke stacks in the morning. If the smoke climbs then stops and spreads out, that is where the inversion is. If it keeps climbing, no inversion is present.”

The 142nd Fighter Wing flies F-15 Eagle fighter jets, guarding the Pacific Northwest skies from northern California to the Canadian border on a 24-hour alert as part of Air Combat Command and the North American Aerospace Defense Command.

The training flights will depart from and land at the Portland International Airport daily after 8 a.m. and will conclude before 4 p.m.


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