A weather system floods St. Louis and Kentucky

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Hundreds of miles apart, but still connected by the same tenacious weather system, the city of St. Louis and the Appalachian countryside show just how devastating flash floods can be when swollen storms dump d huge amounts of rain with nowhere to go.

In St. Louis, the cobbled city environment could not absorb the intense rains. In Kentucky, Virginia, and West Virginia, steep hills and a terrain of narrow river channels brought water to the same place.

Although a single storm system triggered the downpours, different geographic features played a part in the middle, ending with the same result: flooding, the second-deadliest weather phenomenon in the United States. Floods kill about 98 Americans a year and last year claimed 146 lives.

“Places like St. Louis and Kentucky, even though they’re different, they’re overwhelmed,” said private meteorologist Ryan Maue, former chief scientist for the National Oceanic and Atmospheric Administration. “There’s just no way to move that much water coming out of the sky fast enough. He has to go somewhere.

A LOT OF RAIN

In Missouri and Illinois, the first batch of showers on Tuesday and Wednesday dropped a foot (30 centimeters) of rain in some places, up to 10 inches (25 centimeters) in others with another 2 to 4 thumbs down Thursday. In eastern Kentucky, 8 to 10.5 inches (20 to 27 centimeters) fell.

“It’s not just the amount of rain that fell, but where it fell, how exposed people were, how close the infrastructure is to where the heavy rain falls or the where the channels rise,” said Kate Abshire, head of flash flood services at the National Weather Services. ‘ Water Resources Department.

In urbanized St. Louis, precipitation that would normally soak into the ground like a sponge has pooled and flooded, Abshire said. In Appalachia, area residents, roads, buildings and rainfall have all been concentrated by flooded river channels, she said.

HOW IT STARTED


It all started with the same weather patterns — a stationary boundary between different pressure systems “that trails between the Central Plains and the Central Appalachians, east to west,” said Bob Henson, a Colorado-based meteorologist and writer. “The same frontal area that triggered the St. Louis flood also triggered the Mid Appalachian flood.”

What’s happening is unstable warm, moist air, pumped from a warm Gulf of Mexico over dry, very hot Texas, is moving along the border and forming storms, one after the other. And they keep hitting the same spot with storms, similar to a line of trains rolling down the track, meteorologists said.

That means “extreme precipitation rates” of one, two and even three inches per hour, said Zack Taylor, senior meteorologist at NOAA’s Weather Prediction Center. “These little episodes of storm systems rolled along the boundary.”

And the storm’s path doesn’t move much to take them elsewhere, instead it “just drags itself out there,” Taylor said.

WARMING AND SHOWERS

As the world heats up, scientists expect more frequent and intense downpours – and this event matches that, meteorologists said. No one has yet done the specific studies needed to attribute these storms to climate change. But these are not the first major floods of the year or even of the season.

Some experts worry that weather forecasting models are not tracking extreme rainfall and are underestimating the amount of rain that will fall. Such was the case last month, when the Yellowstone area suffered mass evacuations due to flooding, and last year when the New York and New Jersey area was battered by the remnants of Hurricane Ida.

Warmer air holds larger amounts of water that it can then dump. In the case of the St. Louis and Appalachian floods, the air coming from the northern Gulf of Mexico is a degree or two warmer than normal for this time of year – and on the way north it passes above a Texas that is breaking records for heat with Galveston spending 10 straight nights among the hottest on record, Henson said.

In both places, showers persist and forecasters see more rain, some heavy, throughout the weekend and into next week.

“The ingredients are definitely there for intense precipitation,” Taylor said.

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Follow AP’s climate and environmental coverage on https://apnews.com/hub/climate-and-environment

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Follow Seth Borenstein on Twitter at @borenbears

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