A severe weather outbreak will threaten 65 million people across more than a dozen states in the Midwest and South, where damaging winds, large hail and strong tornadoes are expected from Tuesday afternoon through the overnight hours.
NOAA’s Storm Prediction Center has issued a Severe Thunderstorm Watch for portions of northern Illinois and northwestern Indiana until 3 p.m. CDT. This watch area includes Chicago.
A line of severe thunderstorms was moving into the Chicago Metro area just after 1 p.m. CT Tuesday, prompting Severe Thunderstorm Warnings for possible wind gusts to 70 mph and baseball-sized hail, along with heavy rains and frequent lightning.
The warning covers nearly 8 million people.
Earlier Tuesday, a supercell tracked across the Quad Cities of Iowa and Illinois, spawning tennis ball-sized hail in Davenport, Iowa.
The same supercell also produced a 90-mph wind gust as it crossed the state border into Moline, Illinois.
But these thunderstorms were just the appetizer for what was to come later Tuesday into Tuesday night.
A large area of severe thunderstorms is expected to develop from Tuesday afternoon through the overnight hours in a swath extending from southeastern Minnesota, southern Wisconsin, Iowa, Illinois and western Indiana southward to portions of Missouri, Arkansas, eastern Oklahoma and eastern Texas.
These storms will pose threats of destructive wind gusts, large hail and tornadoes, some of which could be long-track, EF-2 or stronger tornadoes.
Two regions are highlighted for an even greater risk of severe weather, shaded in dark red and magenta on the map below.
This includes a northern area from central Missouri into central and eastern Iowa, far southern Wisconsin and western Illinois. The storms in this region are expected to occur mainly during the afternoon and evening.
The other area is farther south and extends from southern Missouri into Arkansas, southeastern Oklahoma and far northeastern Texas. In this region, the severe weather is expected to occur mainly during the overnight hours and into early Wednesday morning. That includes the potential for dangerous nighttime tornadoes, which are more than twice as to turn deadly than twisters that happen during the day.
Tuesday and Tuesday night’s significant severe weather threat includes St. Louis, Madison in Wisconsin, Cedar Rapids and Des Moines in Iowa, Springfield in Missouri and Little Rock in Arkansas.
The weather pattern responsible for this severe weather outbreak is nearly identical to the one that brought deadly tornadoes to the central U.S. last Friday. This includes a potent upper-level jet stream disturbance pivoting into the Plains and Mississippi Valley, providing wind shear – the change in wind speed and direction with height – that will overlap with moisture streaming north from the Gulf of Mexico into the Midwest and South.
Another round of severe weather is expected Wednesday as the storm system slides east into the Great Lakes, Ohio Valley and mid-South.
Damaging wind gusts, large hail and at least a few tornadoes are the main threats in those regions. Some EF-2 or stronger tornadoes are not ruled out.
In western portions of the highlighted threat area on the map below, severe storms could be ongoing early Wednesday morning before the severe weather threat spreads east and intensifies throughout the day.
Chicago, Detroit, Indianapolis, Columbus in Ohio and Memphis in Tennessee are among the cities included in Wednesday’s risk of severe storms.
Isolated strong to severe thunderstorms could linger on Thursday across parts of the mid-Atlantic, including Philadelphia, Baltimore and Washington.
Damaging wind gusts, large hail and an isolated tornado are possible.
A separate risk of severe storms is possible in portions of Deep South Texas, where large hail will be the primary threat.
