Severe weather is expected to strike again across the Midwest and South, bringing a threat of damaging wind gusts, large hail and tornadoes, the latest in a relentless run of springtime storms in recent weeks. This time around, forecasters are also concerned about the potential for life-threatening flooding, as a storm system is expected to stall over parts of the region for several days.
Here are the key things to know:
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This will be an all-day event as the storm system slowly pushes east.
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Cities including Memphis, St Louis, Nashville and Cincinnati may see tornadoes.
Meteorologists warn that the system will not move quickly, which will allow heavy rains to persist over multiple days, from Wednesday through the weekend. That may lead to “significant and potentially historic” rainfall totals, which will increase the risk of flash flooding, particularly in a region stretching from northeast Arkansas through the mid-Mississippi Valley and into southern Indiana.
“One of the problems is that this storm system isn’t going to be allowed to continue moving east,” said Richard Bann, a meteorologist with the Weather Prediction Center. An area of high pressure off the Atlantic coast will block it, he said, keeping the storm stalled while warm, moisture-laden air from the Gulf fuels heavy downpours. “That’s the crux of our concern” Mr. Bann said.
The Weather Prediction Center has placed areas from northeast Arkansas through the mid-Mississippi Valley and into southern Indiana under a threat of “moderate risk,” what it calls a level 3 out of 4, for excessive rainfall from Wednesday through Sunday.
The Weather Service in Paducah, Ky., has warned that these areas are likely to receive between six and nine inches of rain, with parts of southeast Missouri, southern Illinois and southwest Indiana potentially receiving up to 12 inches.
This storm has been building for days.
This storm system originated on the West Coast on Monday, where it brought heavy snow to the Sierra Nevada mountain range, which straddles California and Nevada. By Tuesday it had moved into the Plains, triggering severe thunderstorms.
But its most widespread and severe threat is expected on Wednesday and Wednesday night, across a region stretching from Illinois, Indiana and Ohio to Arkansas, Louisiana and Texas.
The Storm Prediction Center has issued an enhanced risk warning — a level 3 out of 5 on its scale — for these areas, cautioning that “widespread” thunderstorms could produce destructive winds, large hail and significant tornadoes. A higher, moderate threat has been issued for northeastern Arkansas, western Tennessee and Kentucky, southeastern Missouri and southern portions of both Illinois and Ohio.
Here’s when and where to expect the severe weather.
Storms are forecast to begin early Wednesday in Kansas, Missouri and the upper Mississippi Valley, strengthening by the afternoon as they push into the Lower Great Lakes. If conditions remain unstable, tornadoes and damaging wind gusts could develop, forecasters warned.
In the mid-Mississippi Valley, including Missouri, Illinois and eastern Oklahoma, warm and humid air will create ideal conditions for severe storm development by late morning. Some of these storms could form into supercells, capable of producing hail larger than two inches in diameter, strong tornadoes and destructive winds. The threat is expected to persist into the evening as storms push into the Tennessee Valley.
Farther south in northeast Texas, northern Louisiana and southern Arkansas, the storm system is expected to be weaker but still volatile enough to produce isolated storms in the afternoon with large hail, strong winds and tornadoes. Later in the evening, additional storms forming near the Red River may produce large hail over parts of southern Oklahoma and northern Texas, according to the Storm Prediction Center.
The pattern of spring storms has been relentless.
This storms follows a series of severe weather events that have battered the central and eastern United States in recent weeks. Most recently, over the weekend, a powerful system swept through many of the same states, bringing damaging winds, power outages and flooding. In Oklahoma, a falling tree fell onto a trailer, killing one person, and three children were killed after a tree struck their vehicle in Michigan on Sunday.
While severe spring storms are common, the excessive rainfall leading to potential widespread flooding is more unusual, Mr. Bann said.
“It’s not something that happens every year, particularly in places like the Ohio Valley, along the Ohio River, Illinois, Indiana and in parts of Ohio, but we have had scenarios like this before.”
The storm is expected to begin moving east later in the week. “Things will finally start getting a real push during the latter part of the weekend” Mr. Bann said.
You can track the risk with our weather maps here.
Nazaneen Ghaffar is a Times reporter on the Weather team. More about Nazaneen Ghaffar
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