Multiple extremely strong tornadoes will likely tear through parts of the Central United States on Wednesday ahead of days of potentially once-in-a-lifetime flooding hits the same region of the Midwest and South, forecasters said.
National Weather Service offices warned of the potential for a “tornado outbreak” across a region that stretches from Texas to Michigan, with special risk alerts in place for the Memphis area, home to 1.3 million people. The storm system generating these tornadoes is expected to stall by Thursday, prompting the government forecasters to issue their highest alert for flooding over this same area as more than a foot of rain may fall over the next five days.
Here are the key things to know:
-
The threat for tornadoes will intensify Wednesday afternoon into the evening.
-
Memphis is the epicenter for where the worst of both the tornado and excessive rainfall threat is expected this week.
-
A broad risk of tornadoes will exist from North Texas northeastward to the southern Great Lakes, with large populations of people at risk of tornadoes in Detroit, Milwaukee, Cleveland, Chicago, Dallas, Indianapolis, St. Louis, Little Rock in Arkansas, Louisville in Kentucky, Columbus in Ohio and Evansville in Indiana.
-
The rain threat shouldn’t be ignored. “This is not your average flood risk,” forecasters with the Weather Service in Memphis warned Wednesday morning.
Meteorologists said that the system will not move quickly, which will allow heavy rains to persist from Wednesday through the weekend. The relentless rain may lead to “significant and potentially historic” rainfall totals of 10 to 15 inches, creating what forecasters called a “generational flooding” event, particularly in a region stretching from northeast Arkansas through western Tennessee, western Kentucky 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 “high risk,” what it calls a level 4 out of 4, for excessive rainfall on Thursday.
A higher risk of excessive rainfall, shouldn’t be taken lightly. Over the past decade, some of the deadliest and most destructive floods have occurred in areas that forecasters said were at this level of risk — and it’s a level they rarely use. Areas that don’t usually experience flooding might in this case.
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 a high risk — a level 5 out of 5 on its scale — for these areas, cautioning that “widespread” thunderstorms could produce destructive winds, large hail and significant long-track tornadoes.
These severe storms could be particularly intense, long-lasting severe storms at this high of a level are typically experienced only once or twice in a lifetime. This higher level of risk is rare. It means forecasters with experience predicting severe storms believe widespread storms are expected to occur near or at this location.
The most likely area for tornadoes is from Arkansas to Indiana but the chance does exist as far south as Texas and as far north as Michigan.
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
Judson Jones is a meteorologist and reporter for The Times who forecasts and covers extreme weather. More about Judson Jones
The post Millions Across U.S. at Risk for Significant Tornadoes and ‘Generational’ Flooding This Week appeared first on New York Times.
