In the evening hours of Good Friday, April 22, 2011, a violent and destructive EF4 tornado, with winds of struck the St. Louis metropolitan area, across the U.S. states of Missouri, and Illinois. The tornado, which was the strongest to hit St. Louis County or City since January 1967, moved through many suburbs and neighborhoods, impacting many homes and businesses in its wake. The worst damage was inflicted in the suburb of Bridgeton, Missouri, where a few homes were heavily damaged or destroyed.
In its track across the St. Louis metropolitan area, the Good Friday tornado, as it is known by the National Weather Service and the press, damaged thousands of homes, left thousands without power, and caused heavy damage to St. Louis Lambert International Airport, closing it for nearly 24 hours. The tornado crossed over the Mississippi River, and tore the roofs off homes in Granite City, Illinois before dissipating. The tornado was part of a major three-day tornado outbreak across the United States, and was one of two intense (EF3+) tornadoes during the event, with the other being an EF3 tornado that occurred in Macoupin County, Illinois on April 19. This aforementioned outbreak preceded the 2011 Super Outbreak.
Meteorological synopsis
Episode narrative
On April 21, 8:00 PM CDT (01:00 UTC), the Storm Prediction Center issued two slight risk areas of severe thunderstorm activity across the central United States, in one region in west-central Texas to southwest Oklahoma, and another over the latter's northeastern corner, eastern Kansas, west-central Missouri and northwestern Arkansas for the following day. A large area of cyclonic flow interacted with two short-wave troughs over the Pacific Northwest. Strong perturbation traveled from eastern Washington and Oregon towards Idaho. A leading, southern trough was forecasted to move eastward across the central Rocky Mountains, eastern Wyoming and the Nebraska Panhandle.
The following day on April 22, 1:00 AM CDT (06:00 UTC) the Storm Prediction Center (SPC) issued a widespread slight risk area spanning from central Texas to western Ohio, alongside a large 2% tornado risk for most of Missouri, Illinois, Indiana and northwestern Kentucky, as one of the two short-wave troughs was forecasted to weaken as it entered Wyoming from the northeast. Meanwhile the leading trough was expected to become even further perturbated, evolving into a 500-millibar low pressure area over northwestern South Dakota by 1:00 PM CDT (18:00 UTC) and accelerate to the east-northeast. Lee cyclogenesis over southeastern Colorado was forecasted to lift northeastwards along a strengthening front extending from southern Kansas to western Illinois, evolving into a triple point cyclone for the occluded surface low associated with the upper trough over South Dakota. At the same time, a cold front was forecasted to sweep eastwards across Missouri, Illinois to Ohio, with it later stalling over northwest Texas to southeast Oklahoma as a secondary, and weaker low developed. Advection and mixing was expected to force the dry line move to the east across west-central Texas and southern Oklahoma by day. The cold front was forecasted to overtake the dry line in south-central Oklahoma towards the surface low, where the triple point should be set up soon. As a result, multiple rounds of thunderstorms were expected to affect portions of this area to the Ohio River Valley, with 1000–3000 J/kg of CAPE from southern Missouri to the Indiana/Ohio state border area.
Event narrative At 1:00 PM CDT (20:00 UTC) on April 22, the SPC, which previously issued a moderate risk for a 45% hatched hail risk at 11:30 AM CDT (16:30 UTC) for eastern Oklahoma, northwestern Arkansas and southern Missouri, alongside a 10% tornado risk for southern regions of both Missouri and Illinois, reported a cluster of storms which fired earlier in the morning around the St. Louis area. This cluster in the area of moderately strong, elevated instability was supposedly associated with the warm advection near the nose of the low-level jet, remaining organized in intensity as the cluster moved eastwards towards the Ohio Valley during the afternoon and evening. A retreating surface warm front over the region was expected to aid and focus the convection the cluster was producing.
Tornado summary
Formation and peak intensity in Bridgeton
The tornado touched down in northern Maryland Heights, Missouri, north of Creve Coeur Lake and east of the Missouri River along Creve Coeur Mill Road, at approximately 7:59 PM CDT (00:59 UTC). Damage was initially limited to EF0-EF1 level damage to trees along Creve Coeur Mill Road. The tornado began moving east, first reaching EF2 intensity near a golf clubhouse, where a flag pole and light were pushed over. The tornado briefly weakened to EF1 before reaching EF3 intensity in a subdivision, where most walls of a house were collapsed. EF2 damage was also found in areas around the house, with EF1 damage in the northern part of the neighborhood along the edge of the track. Low-end EF2 damage continued further east. After crossing Interstate 270, the tornado weakened to EF1 intensity as it impacted more homes on the other side of the highway.
As the tornado moved into Bridgeton, it reached EF4 intensity along the northern flank of Old St. Charles Road, with a home having all its walls collapse from estimated wind speeds of . Several homes nearby suffered EF3 damage, and trees in the area were debarked and denuded. A condo in the area was also heavily damaged by the winds, with a large portion of the roof and decking being torn off. The tornado then tracked over Beaverton Drive, where several newly constructed homes were destroyed at high-end EF3 strength. The tornado continued through residential areas before crossing MO 180, where a large retail building had several walls collapse. The tornado then tracked over Fee Fee Road, with a power distribution facility on the western side of the street having several exterior walls severely damaged at low-end EF3 intensity.
Impact at St. Louis Lambert International Airport The tornado weakened to a high-end EF1 as it crossed US 67 and Interstate 70, damaging some houses in neighborhoods to the east. The tornado then abruptly strengthened to EF2 intensity turned slightly north as it hit the eastern section of St. Louis Lambert International Airport at around 8:10 PM (01:10 UTC).
Concourse C had a large section of its roof torn off when the tornado struck. Many windows at the airport were blown out, and signs were damaged as well. Vehicles outside were tossed by the tornado, including a van that was partially pushed over the edge of a parking garage. Lambert International Airport released a surveillance video showing debris swirling inside the airport as people ran for cover. It was reported that an aircraft was moved away from its jetway by the storm, with passengers still on board. One plane from Southwest Airlines was damaged when the wind pushed a conveyor belt used for loading baggage into it. American Airlines stated that four of its planes were damaged, two of them significantly. One was struck by crosswinds while taxiing in from a landing when the tornado hit and the other had possible damage to its landing gear.
Continuation in Missouri and crossing into Illinois The tornado continued at low-end EF2 intensity as it moved into the suburbs of Berkeley, Kinloch and Ferguson, where many homes suffered roof loss, along with Berkeley High School, which did not suffer much damage, however, tree and outbuilding damage was reported around the edges of the property. Homes on the western edge of Kinloch saw EF2 damage, while the Kinloch City Hall was narrowly missed. EF1 tree damage with occasional EF2 damage to structures continued through Kinloch and the eastern part of Berkeley. The tornado would move just to the north of the downtown area of Ferguson. A restaurant and church on Blackburn Avenue lost the majority of their roofing, with several windows being broken at the church. More low-end EF2 damage was reported to houses northeast of downtown Ferguson. The tornado weakened back to EF1 intensity further east, where light damage was reported at the Griffith Elementary School. The tornado passed north of the main areas of Dellwood, where houses and trees would be damaged at EF1 intensity, however, some areas of EF2 damage were reported at several locations east of Dellwood, which included several large power poles that were snapped. The tornado continued into the community of Bellefontaine Neighbors, where light to moderate roof damage was reported at several homes. Isolated low-end EF2 damage was found, but most damage was EF1-level in this area. Further east, trees and some homes suffered low-end EF1 damage.
Light tree damaged occurred at North Riverfront Park before the tornado crossed the Mississippi River into Illinois. Low-end EF1 damage would occur in areas west of Nameoki Township, with the tornado narrowly missing an industrial park along Highway 3. The tornado reached EF2 intensity for the last time in areas north of Maryland Place and Pontoon Beach, before dissipating just to the north of Pontoon Road at 8:31 PM (01:31 UTC).
Storm surveys Historical statistics
The 2011 Good Friday EF4 tornado, became the strongest tornado to effect the city and metro of St. Louis, Missouri, in over 44 years. The last violent tornado to affect the area, a deadly storm rated an F4 on the Fujita scale, occurred on January 24, 1967. In fact, the local National Weather Service (NWS) weather forecasting office, stated that the paths of the 2011 and 1967 tornadoes were very similar to one another.
The April 22, 2011 storm was the first violent (EF4+) tornado to strike the state of Missouri, since the EF4 tornado in 2008 that struck areas in Newton County, and the last one until the devastating EF5 tornado exactly a month after, on May 22. When it comes exclusively to EF4 tornadoes, the state would see its first one over five years later, when a deadly EF4 tornado struck Perry County on February 28, 2017. The Good Friday tornado also was the second violent (EF4+) tornado by chronological order, to occur during the 2011 season. The first one was an EF4 satellite tornado that took place in Pocahontas County, Iowa 13 days earlier, on April 9.
Damage assessment Initial findings
On Saturday, the day after the tornado, NWS surveyors from the regional weather forecasting office assessed the damage across portions of northern St. Louis. By 11:45 AM CDT (16:45 UTC) on April 23, one survey team out of four noted that there was at least EF3 damage found in parts of the northern suburbs. Later the same day, EF1 damage was discovered by a different tornado near New Melle, located within St. Charles County, Missouri, and west of St. Louis Lambert International Airport.April 22nd Tornadic Supercell Greater St. Louis Metropolitan Area, National Weather Service, St. Louis, Missouri. (April 23, 2011). Across the state border in Illinois, at around 2:00 PM CDT (19:00 UTC) surveyors from the NWS St. Louis, Missouri office reported EF2 damage near Pontoon Beach along a wide swath from Levee Road, to the south of I-270.
It was not until 3:05 PM CDT (20:05 UTC) on April 23, that an NWS survey team discovered the first instances of EF4 damage, in the Bridgeton, Missouri area near Old St. Charles Rock Road and Harmann Estates. This was before other assessment teams were able to reach Lambert International Airport. After 6:00 PM CDT (23:00 UTC) or over three hours after the discovery of EF4 damage, NWS teams descended on the international airport. After examinations, they concluded during the preliminary assessments, that the highest rated damage at the airport was of EF2 intensity. Almost 80% of the windows were compromised in the easternmost section of the impacted terminal. Concourse C had its roof torn off by the storm.
Verdict