For Grays Harbor, linked inextricably with the ocean, the threat of a tsunami driving ashore and thrashing the lowlands of the region is a perpetual one.

The state of Washington will hold a full-dress drill of its tsunami warning systems on Thursday, called the Great Washington ShakeOut.

“All of our tsunami warning sirens will be going off on Thursday with the actual wailing sounds,” said Hannah Cleverly, deputy director of Grays Harbor County Emergency Management. “I think that’s a big change for most residents.”

At 10:20 a.m. on Oct. 20, Sirens will test, using their real warning sound, and apps will sound an alert, according to a news release from the state’s Emergency Management Division.

The threat of tsunamis is not an idle one; the Emergency Management Division issued a tsunami advisory just months ago following the January Tonga eruption, Cleverly said. The division has maps for all of Grays Harbor County’s major lowland population centers and where it is safe to go.

“One of the important things to remember is this is a worldwide drill. It’s a good time to look at your plans and supplies you have at home,” Cleverly said. “We encourage people to speak with their loved ones about what they’d do if these events occur — where’d they go.”

More than 120 tsunami warnings will wail doom upon their communities across the state, including Ocean Shores, Westport, Hoquiam and more. The alert will be prefaced by announcements in English and Spanish, Cleverly said. Some organizations will practice by sheltering in place, while others have carried out full drills in the past, walking students to high ground, Cleverly said.

“It’s a good time to look at the maps. Where is your safe route to get to high ground if there’s a tsunami?” Cleverly said. “It’s a good time to really nail down their communications plan.”

Having those plans in place ahead of time can help families reconnect in the aftermath of an event, Cleverly said, when family members may have been at three or four different locations during the day. It’s entirely possible cellular communications may be impacted in the aftermath of a major event, and having a designated rendezvous spot can help families to reconvene in one place.

Residents can sign up for emergency alerts from the county, including warning of Thursday’s drill, at the Grays Harbor Emergency Management Division’s website.

Contact reporter Michael S. Lockett at (757) 621-1197 or mlockett@thedailyworld.com.