The tornado outbreak and derecho of May 8, 2009, colloquially known as the 2009 Super Derecho, was an extreme progressive derecho, tornado outbreak, and mesoscale convective vortex (MCV) event that struck southeastern Kansas, southern Missouri, and southwestern Illinois on May 8, 2009. Thirty-nine tornadoes, including two of EF3 strength on the Enhanced Fujita Scale, were reported in addition to high non-tornadic winds associated with the derecho and MCV. Due to the abnormal shape of the storm on radar and the extremely strong winds, many called this an "inland hurricane."Some residents of southern Illinois, in the tradition of giving female names to hurricanes, informally dubbed this storm "Ada May", in commemoration of its date, "eight o' May." Notably, this storm had a defined eye akin to a tropical storm, which occurred alongside intense sustained winds of at the surface level, not associated with the bowing convection typical of a derecho. A new proper class of storm, the "super derecho", has been used to describe this event after analysis in 2010. Embedded supercells produced hail up to baseball size in southern Missouri, a rare event in a derecho. A wind gust of was recorded by a backup anemometer at the Southern Illinois Airport after official National Weather Service equipment failed. This derecho was the last of a series of derechos that occurred at the beginning of May.
Meteorological synopsis
A complex of thunderstorms formed over northwestern Kansas overnight May 7 and into the early morning hours of May 8, before moving into south-central Kansas, where greater moisture and stronger upper-level winds were present. The cluster of storms began to evolve into a more organized derecho near Hutchinson, Kansas, where National Weather Service damage surveys found winds greater than started, then continued through southern Missouri.
While in southwestern Missouri, the derecho began to change; supercells began to embed within the line, and a wake low began to form in conjunction with a bookend vortex on the northern end of the derecho. As the derecho entered southeastern Missouri, the initial line associated began to weaken, but the MCV became increasingly pronounced on the northern end.
Many experts and NWS meteorologists considered this to be one of the worst derechos and MCVs in the past decade. The Storm Prediction Center issued two "particularly dangerous situation" severe thunderstorm watches and a vividly worded tornado watch, mentioning the possibility of winds in excess of . Local National Weather Service offices in Springfield, Missouri, and Paducah, Kentucky, also issued strongly worded severe thunderstorm warnings, with precautionary statements similar to those used in tornado warnings.
As both the initial squall line and MCV weakened, very little severe weather was reported between southern Illinois and central Kentucky. However, as the weakening squall line encountered higher instability and more favorable upper-level winds, the line split into several supercells in a process still not fully understood; these storms produced several tornadoes in central Kentucky, eastern Tennessee, southwestern Virginia, and northwestern North Carolina. While no longer producing severe weather itself, the MCV continued to enhance thunderstorms early the next morning across southeastern Virginia before finally moving out into the Atlantic Ocean.
Other similar events Despite it at first seeming extremely rare, further research has found that similar storms have occurred previously. One case, which occurred in North Carolina on April 15, 1999, produced a killer tornado and a wind gust, although this may have been associated with a tornado. Another heavily studied event in northern Pennsylvania on July 21, 2003, also resulted in several tornadoes. However, these events lasted for a much shorter period of time and were significantly smaller; numerical modeling has shown that an average bookend vortex is only across, while the May 2009 storm reached up to in diameter.
Confirmed tornadoes
May 8 event List of reported tornadoes - Friday, May 8, 2009 EF# Location County Coord. Time (UTC) Path length SummaryMissouri EF1E of PilgrimDade1253Brief tornado damaged several trees and outbuildings along an intermittent path. EF1Republic areaGreene1305Short-lived tornado tracked through downtown Republic, damaging about 50 structures. Losses from the storm reached $1 million. EF1NW of Springfield-Branson National AirportGreene1314A brief tornado touched down near Springfield Airport, destroying a few outbuildings and heavily damaging a home. Losses from the storm reached $200,000. EF1NW of BrightonPolk1316An EF1 tornado damaged or destroyed several barns and outbuildings and caused moderate to severe damage to frame homes. Losses from the storm reached $2 million. EF0Ebenezer areaGreene1321Several trees and outbuildings were damaged. EF1SE of Swan to SW of MerrittTaney, Christian, Douglas1325A wide, relatively long-tracked tornado tracked for through three counties. The most severe damage took place in Christian County, where two homes were damaged, and several outbuildings were destroyed. Losses from the tornado reached $2.6 million. EF1E of FordlandWebster1338A dairy farm lost its roof, a truck was lofted over a fence, and an outbuilding was destroyed. EF2W of GoodhopeDouglas1339A short-lived tornado tore the roof off a home and damaged numerous trees. EF2N of MerrittDouglas1339A short-lived but very large tornado damaged two homes and several outbuildings. Losses from the storm reached $200,000. EF2ESE of MarchDallas1341A wide tornado made several touchdowns along a path. Peaking at EF2 intensity with estimated winds of , the tornado destroyed three framed houses and numerous outbuildings. Two people were injured and had to be transported to a local hospital; one died of a heart attack en route. EF1N of AvaDouglas1400A barn was destroyed, and a few homes suffered minor damage. EF1NW of HartvilleWright1402Several outbuildings were destroyed, and numerous trees were uprooted. EF1SW of WasolaOzark1411Seven outbuildings were destroyed, and three homes were damaged; intense tree damage was also noted. EF0ESE of Mountain GroveTexas1422Several buildings were damaged and numerous trees were uprooted. EF1WNW of Peace ValleyHowell1435A few homes and numerous trees were damaged. EF2W of Mountain View to SE of SummersvilleHowell, Texas, Shannon1435A farmhouse was lifted and moved, injuring two people. Two auto shops and several homes and outbuildings were damaged or destroyed. Numerous trees were snapped or uprooted. EF2SE of LebanonLaclede1440Four homes and several outbuildings were damaged. EF1ESE of HazeltonTexas1444One barn was destroyed, and one mobile home lost its roof. EF2SW of Alley SpringShannon1445Several buildings and a cabin at a sawmill were destroyed. Trees suffered extensive damage. EF3NW of PomonaHowell1500One house, one mobile home, one travel trailer, two outbuildings, and an auto shop were destroyed. Cars were tossed away, and two school buses were blown over. EF0McBride areaPerry1620Damage limited to trees; the tornado was caught on tape. EF1SE of FredericktownMadisonunknown EF1N of EllingtonReynoldsunknownTwo homes had roof damage; trees suffered significant damage.Illinois EF1WSW of Du QuoinJackson1630Structural damage to two barns, shingle damage to homes, power poles blown over, and dozens of trees were snapped or uprooted. EF1N of Thompsonville to NE of Crab OrchardFranklin, Williamson1945Trees were damaged in a rural area. EF0N of RoyaltonFranklinunknownunknownA brief tornado touchdown was photographed.Kentucky EF1E of HisevilleBarren, Metcalfe1904Three outbuildings were destroyed, and one home and a pole barn were damaged. EF3S of RichmondGarrard, Madison, Estill2055at least 2 deaths – Homes suffered severe damage. Several cars were flipped over. Five people were injured. EF0NW of IrvineEstill2123less than Two structures had metal roofing torn off. Several trees were knocked down, including one that damaged the porch of a home.Tennessee EF2SE of HuntsvilleScott2254Seven homes were damaged, and a freestanding cellphone tower collapsed. EF2SW of TazewellClaiborneunknownTwo large barns were destroyed, and one home lost its roof. EF1NE of Thorn HillGrainger, Hancock2336Barns and outbuildings were damaged heavily, and several homes suffered roof damage. EF0S of GrayWashington0045unknownTornado touchdown was reported by law enforcement, but no damage reported. EF0NW of EtowahMcMinnunknownA tornado briefly touched down, causing damage to several trees.Virginia EF0N of ClintwoodDickenson0100Numerous trees were uprooted, one of which fell on a mobile home. Two homes suffered minor roof damage. EF2SE of PoundWise0145Two trailers and several outbuildings were destroyed, and a third trailer was damaged. EF0NW of LebanonRussell0225A tornado briefly touched down without any known impact. EF2NE of LebanonRussell0230One barn was destroyed, one home had moderate damage, and 100 trees were snapped or uprooted.North Carolina EF2NW of EnniceAlleghany0344A mobile home was destroyed, injuring four people. Five homes and several outbuildings were damaged, and cement silos were toppled, causing two additional injuries. Damages from the tornado amounted to $200,000. EF1SW of EnniceAlleghany0346Three outbuildings were destroyed, and one home and a pole barn were damaged. Sources:National Weather Service Springfield, MO, National Weather Service St. Louis, MO, National Weather Service Paducah, KY, National Weather Service Louisville, KY, National Weather Service Jackson, KY, National Weather Service Morristown, TN
Effects
Kansas and southwestern Missouri
The initial squall line formed in central Kansas, to the northwest of Hutchinson. In Hutchinson, several airplanes were flipped at a local airport, and 21,000 people were left without power. A woman was killed in New Albany, Kansas, when her mobile home was blown forty feet off of its foundation. National Weather Service survey teams found that winds reached in the area, which also resulted in the destruction of a church and the town's post office, in addition to damaging several homes. A total of 130 buildings were damaged in Cherokee, Kansas, including a high school gymnasium. Schools in several counties closed for the day, and a twenty-mile stretch of the Kansas Turnpike was closed for an hour due to flooding.
The derecho continued to intensify as it reached southwestern Missouri, where the storm forced several television stations in Joplin, Missouri, off the air after their transmission towers were downed; one station's tower landed on its studios. Numerous schools were damaged throughout the Springfield, Missouri, area, including a roof collapse at the Fair Grove High School, resulting in three injuries to students. There were numerous reports of tree and roof damage throughout Springfield, prompting some business to close. Drury University canceled some morning classes. A total of 346 buildings suffered some damage in Greene County, Missouri, and four people were injured, but none required hospitalization. A high school in Fair Grove suffered damage.
Southeastern Missouri and southwestern Illinois
As the initial line weakened, the mesoscale convective vortex on the northern end began to strengthen and separate from the squall line. A long-lived supercell formed within the MCV in Madison County, Missouri, producing hail up to baseball size and a few tornadoes, in addition to the more widespread, damaging, straight-line winds throughout the area.