From May 25–30, 2019, a significant and deadly tornado outbreak took place across the Great Plains, Ohio Valley and parts of the Northeastern United States. Approximately 182 tornadoes touched down over a five-day period, two of which were violent. It was the final significant outbreak during the month of May, coming days after a similarly large and deadly outbreak impacted areas further west. Following two days of significant tornadoes within the Central Plains, the Storm Prediction Center (SPC) first noted the possibility for an outbreak in the Ohio Valley on May 27 with a 10% hatched region for tornadoes. A large outbreak of strong to violent tornadoes impacted the region that night, including an EF3 tornado that caused severe damage in Celina, Ohio, killing one person there and injuring eight others. Dayton, Ohio and its surrounding suburbs were hit by EF4, EF3, and EF2 tornadoes in quick succession, resulting in widespread major damage throughout the metro area, and at least 166 injuries. On May 28, the SPC issued a moderate risk of severe weather for portions of Nebraska and Kansas, where a violent, rain-wrapped EF4 wedge tornado impacted the outskirts of Lawrence and Linwood, Kansas, destroying many homes and injuring 18 people. The damaging series of tornadoes that occurred in Indiana and Ohio on the evening of May 27 during this event is sometimes locally referred to as the Memorial Day tornado outbreak of 2019, which became the fourth costliest weather event in Ohio history. The near continuous stream of systems also produced widespread flash and river flooding, along with damaging winds and large hail.

As the outbreak occurred within a broader period of significant tornado activity during the month of May, on May 29, the U.S. had its 13th straight day with at least eight tornadoes, which broke the previous record of 11 days straight set in 1980. On the day when the record was broken, the U.S. had an average of 27.5 tornadoes per day during the period.

The thunderstorms associated with this outbreak also produced frequent heavy rainfall, sometimes at record levels, on previously saturated ground across the U.S. and eastern Canada. This resulted in widespread river and lakeshore flooding and flash flooding, which frequently interfered with emergency crews responding to tornado damage, and also interfered with National Weather Service damage surveys. The new precipitation also extended existing flooding along the Mississippi River system to record durations.

Overall, three people were confirmed to have died from tornadoes as a result of the outbreak, with one fatality being attributed to non-tornadic effects. 239 people were injured in some degree, while total damages were estimated to be approximately $4.53 billion (2019 USD).

Meteorological synopsis May 25

As persistent southwesterly mid-level flow continued to engulf the Central Plains, the SPC once again warned of the potential for widespread severe weather, outlining the Texas Panhandle, western Oklahoma, and southern Kansas in an enhanced risk. This included a 10% risk of tornadoes. An area of low pressure was expected to progress over the southern High Plains, supporting a southward-extending dryline and a northeast-extending cold front to the Iowa–Missouri border. Within the warm sector, mid-level CAPE values were forecast to rise upwards of 2,000–3000 J/kg, with dewpoints in the mid-60s °F as far west as eastern New Mexico. Thunderstorms began developing along the dryline in eastern New Mexico and western Texas around noon local time, though these storms were not tornadic in nature in the absence of strong low-level shear. By the late afternoon, more transient supercell structures had become apparent, leading to a few tornadoes across the Texas Panhandle. One such tornado was rated an EF2 as it struck the north edge of Plainview, Texas, destroying outbuildings, a mobile home, and a cell phone tower. Several weak tornadoes also occurred across the Ohio Valley, where a well-defined shortwave trough combined with abundant moisture and sufficient instability to produce supercell thunderstorms. This included an EF1 tornado that caused moderate damage in Carrollton, Ohio. Hundreds of damaging wind reports were received as well. Through the evening, earlier discrete activity across Texas and Oklahoma congealed into an organized mesoscale convective system. Weak mid-level winds were expected to mitigate the tornado risk, owing to a severe thunderstorm watch across central Kansas down into central Oklahoma. However, as squall line approached Oklahoma City, multiple areas of rotation unexpectedly began to form within the line. At 10:28 p.m. CDT, a low-end EF3 tornado embedded in the squall line moved through southern sections of El Reno, Oklahoma, causing severe damage, killing two people and injuring 29 others. Several other weak tornadoes also touched down around the Oklahoma City metropolitan area. A total of 17 tornadoes were confirmed.

May 26 Into the morning of May 26, the mesoscale convective system continued to push across eastern Oklahoma, leading to two simultaneous, large EF1 tornadoes in Sapulpa. These weak, but wide tornadoes caused widespread damage to trees, power poles, homes, and businesses in town. Into the afternoon, a concentrated risk for severe weather was once again expected to exist across the Central and South Plains. Several days of convection had eroded the elevated mixed layer throughout the region, but broad and intensifying southwesterly flow across northern Mexico was expected to reinvigorate this plume. Underneath the potent mid-level flow, rich low-level moisture was forecast to surge into western Kansas and eastern Colorado while mid-level CAPE values were projected to top 3,000 J/kg. While initiation of thunderstorms was expected in the early afternoon (with the threat for large hail being the primary threat initially in the presence of weak low-level wind shear), more expansive cloud cover and a stronger cap delayed initiation. Later in the day, a cluster of storms formed across portions of Nebraska and Kansas, with a severe squall line taking shape farther south across the Texas and Oklahoma panhandles as stronger upper-level winds arrived. Numerous tornadoes were reported throughout the area, most of which were weak. The most significant event of the day was a large, EF2 stovepipe tornado that passed near the town of Dora, New Mexico. The tornado damaged two homes, snapped numerous power poles, and completely destroyed a barn. Another EF2 tornado downed electrical transmission lines near Earth, Texas, as well. A total of 35 tornadoes were confirmed.

May 27

As a strengthening mid-level westerly flow moved over the Midwest, the SPC issued an enhanced risk of severe weather at 0600 UTC, including at 10% risk of tornadoes that outlined the northern region of Illinois. At 1300 UTC, the risk was upgraded to feature the possibility of significant tornadoes, while still retaining its 10% probability. A lesser threat of tornadoes also existed in far western portions of Nebraska and northeast portions of Wyoming, as a prominent upper trough shifted east-northeastward from the Four Corners area into the High Plains. Significant tornado activity began early in the day, with an EF3 tornado that passed near Cantril, Iowa, destroying a farmhouse and a hunting cabin. A high-end EF1 tornado also impacted the western fringes of Charles City, causing heavy damage to buildings at the local fairgrounds, a fertilizer plant, and a few homes. Throughout the afternoon, there was increasing concern over the possibility of strong tornadoes impacting the Chicago metropolitan area. Supercell thunderstorms developed in northern Illinois, and three tornadoes moved through the eastern suburbs of Chicago. However, these tornadoes were weak and only caused minor damage. As the supercells pushed into Indiana, strong tornadoes began touching down, including an EF2 that caused significant damage to homes and trees in the town of Pendleton. A large EF3 wedge tornado destroyed a house, multiple metal truss transmission towers, and several outbuildings near Akron. Another EF3 tornado passed near Montpelier, destroying a trailer manufacturing warehouse, and severely damaging a dairy farm, killing numerous cows.

Tornado activity was expected to lessen after dark as the storms crossed into Ohio. However, unexpectedly high CAPE, shear, and helicity was in place in the region, and the activity only intensified as numerous tornadic supercells overspread the state, producing numerous intense tornadoes. An EF3 tornado destroyed numerous homes in Celina, Ohio, and killed one person, while another EF3 tornado passed north of West Milton and through the small community of Kessler, damaging or destroying many homes and outbuildings. The most significant event of the night occurred when Dayton, Ohio and its surrounding suburbs were struck by three powerful tornadoes in quick succession, with the tornadoes rated EF4, EF3, and high-end EF2 in intensity. Widespread major damage to numerous homes, businesses, apartments, industrial buildings, and other structures occurred throughout the Dayton metro. Remarkably, no direct fatalities occurred in the Dayton area, though at least 166 people were injured. May 27 was the most active day for tornadoes during the outbreak sequence, with a total of 59 confirmed tornadoes.

May 28

Tornado activity that began in Ohio on the evening of May 27 continued into the early morning of May 28. An EF2 tornado passed near Jamestown, Ohio, severely damaging a house and destroying outbuildings. Another EF2 tornado passed near Laurelville, causing significant damage to homes and trees, and tossing a propane tank and a truck. A high-end EF1 tornado also struck Roseville, downing numerous trees and power poles, and damaging several homes.

Later that morning, the SPC issued an enhanced risk for severe weather at 0600 UTC; denoting a 10% risk of significant tornadoes along the Missouri and Iowa border as well as parts of Kansas, Nebraska, and Illinois. At 1300 UTC the SPC upgraded the risk to moderate for a 15% chance of significant tornadoes, namely around the MO/KS/NE borders; with a 10% chance of tornadoes extending southward to include much of eastern Kansas. By 2000 UTC the SPC had downgraded the forecast for significant tornadoes to 10%, but this time including Kansas City as the risk was shifted southward due to a stubborn cold front to the north. Further east, an enhanced risk was in place across most of Pennsylvania, along with part of Ohio and New Jersey. This eastern risk area included a 5% risk of tornadoes. Later that afternoon, an EF2 tornado moved through Morgantown, Pennsylvania, damaging numerous homes, businesses, and vehicles. Later that evening, a large EF4 wedge tornado grazed the southeastern edge of Lawrence, Kansas, before impacting the western fringes of Linwood, destroying numerous homes and agricultural buildings, debarking and denuding many trees, and injuring 18 people. Further west, a large EF2 tornado passed near Waldo and Tipton, Kansas, snapping trees and power poles, and damaging several farms. Another EF2 tornado occurred near Kearney, Missouri, and damaged a few homes, one of which sustained roof and exterior wall loss. A total of 27 tornadoes were confirmed.

May 29–30