This past week, a slow-moving, upper-level system moving through the central U.S. triggered several days of severe weather. The system caused numerous tornadoes, as well as heavy rains and flooding from the Deep South up through the middle Mississippi River Valley and into the Ohio River valley. 

The situation began when an upper-level area of low pressure situated over the northeast Pacific pivoted down into the central Rockies, creating a deep trough of low pressure aloft that extended down into the northern Baja. This channeled strong jet stream winds from south of the Four Corners region up through the Central Plains, while at lower levels a strong area of low pressure was induced at the surface over northern Kansas. The combination of southerly flow east of the surface low and upper-level trough at low levels and return flow from a strengthening Bermuda High off the southeast U.S. coast opened up the Gulf, allowing moisture to stream northward into the central part of the country, while the combination of southerly winds at low-levels and strong southwesterly winds aloft provided wind shear, setting the stage for the development of strong, rotating thunderstorms, including tornadoes. The slow forward progression of the entire pattern allowed for strong thunderstorms to erupt in the same region for several days in a row. The result was a multi-day tornado outbreak that lasted from April 2-6, 2025, with at least 63 confirmed tornadoes according to the National Weather Service. Fortunately, there were no confirmed EF4 or EF5 tornadoes; however, there were 6 rated at EF3. The most widespread event was on April 2, 2025, when tornadoes touched down from Arkansas up through the Ohio Valley and into southern Michigan. However, the deadliest tornado occurred early on the morning of April 3, 2025, when an EF3 tornado struck Selmer, TN.

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In addition to the tornado threat, the widespread thunderstorm activity over several days also resulted in heavy rains and flooding across the region. The above animation shows a week of surface rainfall estimates from NASA's IMERG precipitation product beginning at 8:00 p.m. ET (00:00 UTC), March 31, 2025. The animation begins with a line of showers and thunderstorms extending southward from the Ohio Valley in association with the previous storm system moving eastward and exiting along the East Coast before new thunderstorm activity erupts over the Central Plains in the association with the new system. This activity quickly organizes into a long line of strong storms ahead of a cold front on April 2, 2025, as it advances eastward toward the Mississippi and Ohio Valleys before weakening over the northern Appalachians. The southern end of this frontal system then becomes the focus for new shower and thunderstorm activity again over the middle Mississippi and southern Ohio River Valleys on April 4-6, 2025. IMERG rainfall totals for the entire period show the heaviest accumulations (on the order of 6 inches or more, shown in purple) stretching from central Arkansas across western Tennessee and Kentucky and up into parts of southern Indiana, Illinois and Ohio.

Locally, several reports of over a foot of rain, including 15.59 inches in Benton, KY, were reported over parts of western Kentucky and western Tennessee. The Kentucky River reached a record high of 47.04 feet south of Lexington on Sunday while the Ohio River reached 60 feet on Monday in Cincinnati. Numerous flood warnings are also in effect along the Mississippi River, which is expected to crest over the coming days.

Credits: 

Animation by Jason West (NASA GSFC, PPS, KBR)
Story by Steve Lang (SSAI / NASA GSFC)