A prolonged period of intense tornado activity affected the Great Plains, Great Lakes, and Ohio Valley during May 15–20, 2017. This outbreak sequence was the most prolific tornado event of 2017 in terms of number of tornadoes. It is also notable for producing the longest-tracked tornado in Wisconsin state history: an intense EF3 tornado that remained on the ground for over and killed one person while causing major damage near Chetek and Conrath. Overall, the outbreak sequence resulted in two deaths and several injuries.
Outbreak summary On May 15, a severe weather outbreak struck areas from Northern Illinois to Texas. One EF0 tornado was reported in Iowa along with minor tree damage associated with the tornado. Numerous reports of strong winds and large hail along with some significant hail and wind was reported on May 15. On May 16, a widespread severe weather event impacted a line from Wisconsin to Texas according to storm reports. Many tornadoes, including some long tracked tornadoes, were reported in Texas, Oklahoma, and Kansas. An EF3 tornado which touched down near Reeve, Wisconsin, caused one fatality and 25 injuries along its long track, making it the longest tracked on record in Wisconsin and the first killer tornado in the state since 2011. Extensive damage occurred in a mobile home park near Chetek, where the fatality occurred, and EF3 strength damage occurred to a poorly built home near Conrath, which was leveled. A large, high-end EF2 tornado also struck the southern fringes of Elk City, Oklahoma, killing one person and causing major damage. An EF3 tornado also damaged houses in Pawnee Rock, Kansas, and completely destroyed farm homes near Great Bend, injuring one person. Hail up to in diameter and straight-line winds up to were also reported on May 16. On May 17, individual storm cells began to pop up along a line from Minnesota to Nebraska. The individual storm cells generated a few tornadoes in Iowa, Nebraska, and Minnesota before converging into a squall line. The squall line continued to produce winds of up to in parts of Wisconsin, Iowa, and Illinois before weakening below severe limits. An EF2 tornado embedded in the squall line ripped the roof off of a house and injured one person near Galva, Illinois.
On May 18, a high risk of severe thunderstorms was issued for south-central Kansas and northwestern Oklahoma. The Storm Prediction Center stated that several intense and long-tracked tornadoes, along with hurricane-force winds and hail up to 4 inches in diameter were likely in the high risk area. Also, a 30% risk of tornadoes including significant tornados was issued in the high risk area. In the early afternoon, a line of intense supercells with baseball size hail fired along the dry line near the Texas and Oklahoma panhandle border. A few of these supercells went on to produce multiple scattered, short-lived tornadoes across three different states. Most were weak, though an EF2 tornado crumpled several metal power line truss towers near Haynesville, Texas. Later in the afternoon when the most intense severe weather was forecast to occur, a stationary front set up in northern Kansas lowering temperatures in most of the moderate and high risk areas. This led to insufficient instability and limited the severe weather in southern central Kansas and West central Oklahoma to smaller hail and winds. However, this also created a large plume of heavy precipitation that caused some flash flooding. In addition, the supercell thunderstorms that formed during this event initiated in the early afternoon, well before the best kinematics for tornado development had arrived. Later in the evening, the tornado threat was limited to central Texas and eastern Oklahoma. A large, slow moving high precipitation supercell with softball sized hail set up near Cross Plains, Texas. This storm was tornado warned for over an hour and produced many funnel clouds along with a couple of weak tornadoes. The main threat with this storm, however, was the flash flooding as it dumped close to of rain in localized areas due to its very heavy rain and slow movement. A squall line progressed through eastern Oklahoma and Kansas overnight, producing many embedded tornadoes, two of which reached EF2 intensity. One of these EF2 tornadoes struck Muskogee, Oklahoma, causing severe damage to trees, apartment buildings, and industrial buildings. A separate EF1 tornado impacted the western part of Muskogee as well, causing damage to homes and businesses, and downing many trees. The squall line continued into Friday morning, eventually making its way to parts of Arkansas and Missouri, producing numerous additional weak tornadoes. Other storms in states further to the west also produced many EF0 and EF1 tornadoes. On May 20, the severe weather threat generally was limited. However, a few weak tornadoes were spawned in Indiana as plentiful helicity and the presence of a warm front aided the development of tornadoes. Overall, this outbreak sequence produced 134 tornadoes.
Confirmed tornadoes
May 15 event + List of reported tornadoes – Monday, May 15, 2017EF#LocationCounty / ParishStateStart Coord.Time (UTC)Path lengthMax width EF0W of CalmarWinneshiekIA23:45–23:47Surveyors found a broken line of tree damage.
May 16 event + List of reported tornadoes – Tuesday, May 16, 2017EF#LocationCounty / ParishStateStart Coord.Time (UTC)Path lengthMax width EF0NE of BalkoBeaverOK19:45–19:46Brief tornado remained over open country and caused no damage. EF0NW of WakaHansfordTX20:04–20:05Brief tornado remained over open country and caused no damage. EF0SSW of McLeanDonleyTX21:39–21:50Tornado remained over open country and caused no damage. EF3WNW of Reeve to N of Chetek to WSW of OgemaPolk, Barron, Rusk, PriceWI21:42–00:101 death – See section on this tornado – There were 25 injuries. EF0NE of ExeterFillmoreNE21:43–21:52A trained storm spotter observed a landspout tornado. An auger was turned over and some tin was removed from a roof. EF0E of McLeanWheelerTX21:53–21:54Brief tornado remained over open country and caused no damage. EF1NNW of ShamrockWheelerTX22:16–22:17A power line and trees were damaged. EF2SE of WheelerWheelerTX22:25–22:44Large rain-wrapped wedge tornado. A double-wide mobile home was completely destroyed, with its debris scattered hundreds of yards downwind. Several other structures were damaged, a large number of power poles were snapped off at the base, and numerous trees were snapped or uprooted. A cotton stripper was overturned, and a truck was tossed nearly . Oil equipment and holding tanks were damaged as well. EF0ESE of AberdeenCollingsworthTX22:45–22:46Brief tornado remained over open country and caused no damage. EF1SE of MinneolaClarkKS22:49–22:58A narrow tornado rolled an RV camper at a storage lot, destroyed an old pole barn, ripped an exterior wall off of a small abandoned house, and tore roof panels off a metal outbuilding. EF0E of LutieCollingsworthTX22:50–22:51Brief tornado remained over open country and caused no damage. EFUS of ErickBeckhamOK23:08–23:11The Erick Fire Department, and storm chasers, observed a tornado. EF2SSE of Reydon to WNW of CheyenneRoger MillsOK23:18–23:30This tornado snapped numerous power poles, tore the roof off of a small hotel and a barn, and uprooted trees. A 16-foot grain feeder that was full of grain was overturned. EFUSSE of ErickBeckhamOK23:23–23:25An NWS employee observed a tornado. EF0WSW of BrandonPerkinsNE23:36–23:37A brief tornado was observed but caused no damage. EF1NNW of Strong CityRoger MillsOK23:45–23:46A tree was blown over and a water tank was damaged at a well site. EF2WNW of Carter to Southern Elk City to WSW of CanuteBeckham, WashitaOK23:46–00:181 death – This rain-wrapped wedge tornado caused very high-end EF2 damage as it impacted the southern fringes of Elk City. Many homes at the Elk City Golf & County Club had their roofs ripped off and sustained collapse of some exterior walls. One small home collapsed, and several metal industrial buildings were heavily damaged or destroyed. Numerous vehicles were flipped and tossed, and one man was killed as his pickup truck was thrown 150 yards from a roadway and mangled. Elsewhere along the path, an oil derrick was toppled, several other homes sustained heavy damage, outbuildings were damaged or destroyed, and an irrigation pivot was overturned. Many trees and power poles were snapped along the path. 66 homes were destroyed, while 140 others were damaged. Three businesses were destroyed, and five others were damaged as well. 10 people were injured. EF3E of Larned to NW of HoisingtonPawnee, BartonKS00:59–01:41This strong tornado struck the town of Pawnee Rock, where a school building sustained considerable damage, trees were snapped, and homes had their roofs ripped off. High-end EF3 damage occurred to the west of Great Bend, where trees were denuded and debarked, a block-foundation farmhouse was completely leveled, and another farmhouse was left with only one corner standing. Several other homes were severely damaged along the path, some sustaining roof and exterior wall loss. Outbuildings were damaged or destroyed, and irrigation pivots were damaged as well. One person was injured. EF0NNE of ParrishOneidaWI01:12–01:13Several hundred pine trees were uprooted by this brief tornado. EF0NNE of SusankBartonKS01:48–01:50Brief tornado remained over open country and caused no damage.
May 17 event