Fast-Moving, Rotating Storm Prompted Tornado Warning in Grays Harbor County


A tornado warning issued for Aberdeen and Hoquiam late Tuesday afternoon brought with it plenty of anxiety, dark skies, strong winds, heavy rain, thunder and lightning, and some noisy isolated hail showers in Hoquiam, but did not result in any reports of a tornado touching down or any damage related to the event.

"Luckily, we didn't receive any reports of damage or get any photos to indicate it touched the ground," said National Weather Service Seattle forecaster Carly Kovacik.

The Weather Service was monitoring several storm spots offshore during the day ahead of the warning.

"Yesterday's event began as special marine warnings. Those are warnings specific to any type of storm over the water we think might cause hazardous weather," said Kovacik. "Within that, we look for indications for the potential for waterspouts. Then once they move onto land we have the ability to issue anything from a severe thunderstorm warning to a tornado warning."

On radar, the Weather Service could see wind velocity and the direction the winds were moving in relation to the location of the radar. On their screens, red indicates winds moving away, green toward the radar.

"We are looking for a really tight couplet where the red is located right next to the green," said Kovacik. This indicates a tight wind rotation, and Tuesday at 4:48 p.m. the Weather Service saw enough rotation to issue a tornado warning for Aberdeen and Hoquiam.

The storm was moving north and east at about 45 knots, "overall a pretty quick event," said Kovacik. Another tornado warning issued by the Weather Service hit at 4:58 p.m., from Moclips east to just north of Humptulips. A minute later, another warning was posted for an area just east of Aberdeen to Elma, north of Highway 12.

At 5:13 p.m. the warning continued, confined to a smaller area north of Humptulips. Five minutes later it was updated to an area around Neilton and Quinault. By 5:32 p.m., all tornado warnings for Grays Harbor County had been canceled.

Kovacik said the event occurred pretty close to a local radar station, which gave forecasters a good opportunity to judge the potential severity of the storm.

"In this case it was nice that the storm was located close to the radar so we had decent radar coverage and were confident in the rotation in the storm," she said.

Tornado warnings are rare but not unheard of in the area, said Kovacik; rotating storms are pretty common across western Washington.

"When looking at the radar, if we issued on every rotating storm there would be a lot more warnings, but we're looking for more organized and persistent rotating cells before we issue a tornado warning," explained Kovacik.


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