    Clockwise from top: Satellite image ofsupercells developing across centralOklahoma late on May 3; a tornado nearAnadarko, Oklahoma; tracks of all the tornadoes spawned by the outbreak in Oklahoma; radar reflectivity image of thethe F5 tornado that impacted Bridge Creek and Moore | |
| Meteorological history | |
|---|---|
| Duration | May 2–8, 1999 |
| Tornado outbreak | |
| Tornadoes | 152 |
| Maximum rating | F5 tornado |
| Duration | 6 days, 1 hour and 35 minutes |
| Highest winds | Tornadic – 321 mph (517 km/h) (Southwest Oklahoma City, OK F5 tornado on May 3)[1][2] |
| Highest gusts | Non-tornadic – 115 mph (185 km/h)(Claxton, TN non-tornadic on May 7)[3] |
| Largest hail | 4.5 in (11 cm) in diameter(multiple locations on May 3)[4] |
| Overall effects | |
| Fatalities | 50 fatalities (+7 non-tornadic) |
| Injuries | 895 |
| Damage | $1.5 billion (1999 USD)[5] |
| Areas affected | Midwestern,Southern United States,Great Plains |
Part of theTornado outbreaks of 1999 | |
The1999 Oklahoma tornado outbreak was a large, historic,[6] and devastatingtornado outbreak that took place across much of theCentral United States, with most tornadoes occurring from May 2–5, 1999; scattered activity occurred afterwards until May 8 in parts of theEastern United States, as well as southernCanada. During this week-long event, 152 tornadoes touched down in these areas. The most dramatic events unfolded during the afternoon of May 3 through the early morning hours of May 4 when more than half of these storms occurred, known locally as theMay 3rd outbreak.Oklahoma experienced its largest tornado outbreak on record from this event, with 70 confirmed. The most notable of these was theF5Bridge Creek–Moore tornado which devastated Oklahoma City and suburban communities. The tornado killed 36 people and injured 583 others; losses amounted to $1 billion, making it the first billion-dollar tornado in history.[7] Overall, 50 people lost their lives during the outbreak and damage amounted to $1.4 billion.[8]
On May 2, a strongarea of low pressure moved out of theRocky Mountains and into theHigh Plains, producing scatteredsevere weather and ten tornadoes inNebraska. The following day, atmospheric conditions across Oklahoma became significantly more favorable for an outbreak of severe weather. Wind profiles across the region strongly favored tornadic activity, with theStorm Prediction Center stating, "it became more obvious something major was looming" by the afternoon hours.[9] Numeroussupercell thunderstorms developed across the state as well as bordering areas inKansas andTexas. Over the following 48 hours, May 3–4, 116 tornadoes touched down across the CentralUnited States. Following the extensive outbreak, activity became increasingly scattered from May 5 to 8, with 26 tornadoes touching down across the Eastern United States andQuebec.[9]
In 2023, tornado expertThomas P. Grazulis published theoutbreak intensity score (OIS) as a way to rank outbreaks.[6] The outbreak received 145 OIS points, ranking it as ahistoric tornado outbreak.[6]
The outbreak was caused by a vigorous upper-leveltrough that moved into theCentral and Southern Plains states on the morning of May 3. That morning, low stratus clouds overspread much of Oklahoma, with clear skies along and west of adry line located fromGage toChildress, Texas. Air temperatures at 7:00 a.m.Central Daylight Time ranged in the mid to upper 60s °F (upper 10s to near 20 °C) across the region, whiledew point values ranged in the low to mid 60s °F (mid to upper 10s °C).[10] TheStorm Prediction Center (SPC) inNorman, Oklahoma, a division of theNational Weather Service, initially issued a slight risk of severe thunderstorms early that morning stretching from the Kansas-Nebraska border to parts of southern Texas, with an intended threat of large hail, damaging winds and tornadoes.[11]
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By late morning, the low cloud cover began to dissipate in advance of the dry line, but during the afternoon hours high cirrus clouds overspread the region, resulting in filtered sunshine in some areas that causedatmospheric destabilization. The sunshine and heating, combined with abundant low-level moisture, combined to produce a very unstable air mass. Upper air balloon soundings observed strong directionalwind shear, cooling temperatures at high atmospheric levels, and the increased potential ofCAPE values potentially exceeding 4000 J/kg, levels that are considered favorable forsupercells and tornadoes.
As observations and forecasts began to indicate an increasing likelihood of widespread severe weather conditions even more favorable for strong tornadoes, the SPC issued a moderate risk of severe weather at 11:15 a.m. CDT for portions of Kansas, Oklahoma and Texas along and near theInterstate 40 corridor.[12] By 3:00 p.m. CDT, it had become evident that a widespread severe weather event was imminent; the Storm Prediction Center upgraded locations within the moderate risk area to a high risk of severe weather around 4:00 p.m. CDT as wind shear profiles, combined with volatile atmospheric conditions, had made conditions highly conducive for a significant tornadic event across most of Oklahoma, southern Kansas and north Texas, including the likelihood of violent, damaging tornadoes.[12] The SPC issued atornado watch by mid-afternoon as conditions gathered together for what would be a historic tornado outbreak. By the time thunderstorms began developing in the late-afternoon hours, CAPE values over the region had reached to near 6,000 J/kg. Largesupercell thunderstorms developed, and in the late afternoon through the mid-evening hours of that Monday, tornadoes began to break out across the state.
| FU | F0 | F1 | F2 | F3 | F4 | F5 | Total |
|---|---|---|---|---|---|---|---|
| 0 | 73 | 44 | 20 | 10 | 4 | 1 | 152 |
 A view of the damage by the tornado. | |
| Meteorological history | |
|---|---|
| Formed | May 3, 1999, 6:23 p.m.CDT (UTC−05:00) |
| Dissipated | May 3, 1999, 7:48 pm. CDT (UTC−05:00) |
| Duration | 1 hour, 25 minutes |
| F5 tornado | |
| on theFujita scale | |
| Highest winds | 321 mph (517 km/h) (as measured by mobileDoppler radar)[1][13] |
| Overall effects | |
| Fatalities | 36 (+5 indirect)[citation needed] |
| Injuries | 583 |
| Damage | $1 billion (1999USD) $1.9 billion (2025 USD) |
At approximately 3:30 p.m. CDT, a severe thunderstorm began forming inTillman County in southwestern Oklahoma; asevere thunderstorm warning was issued for this storm by theNational Weather Service Weather Forecast Office in Norman at 4:15 p.m. CDT. The storm quickly developed supercell characteristics and began exhibiting potentially tornadic rotation, resulting in the National Weather Service issuing the firsttornado warning of the event forComanche,Caddo, andGrady counties approximately 35 minutes later at 4:50 p.m. CDT.
The first tornado from this supercell touched down 7 miles (11 km) east-northeast ofMedicine Park at 4:51 p.m. CDT; it produced four additional tornadoes as it tracked northeast intoCaddo County, the strongest of which (rated as an F3) touched down 2 miles (3.2 km) west-southwest ofLaverty and dissipated 2.5 miles (4.0 km) west-northwest of downtownChickasha. This large tornado had exhibited a companionsatellite tornado for a few minutes.[14]
The storm produced the most significant tornado of the outbreak, which touched down just southwest of the Grady County community ofAmber at 6:23 p.m. CDT and headed northeast, parallel toInterstate 44, just after another tornado had passed over the airport inChickasha. The storm continued moving northeast, destroying the community ofBridge Creek and crossing I-44 just north ofNewcastle. The tornado then crossed theCanadian River, passing into far southern Oklahoma City. As it passed overBridge Creek, around 6:54 p.m., aDoppler On Wheels mobile Dopplerweather radar detectedwind speeds of 302 mph (486 km/h) – later revised to 321 mph (517 km/h) – inside the tornado at an elevation of 105 ft (32 m).[1][15] These winds, however, occurred above the ground, and winds at the surface may not have been quite this intense. The tornado continued on into Moore, then passed over the intersection of Shields Boulevard andInterstate 35 and back intoOklahoma City, crossingInterstate 240 near Bryant Avenue. The storm then turned more northerly, striking parts ofDel City andTinker Air Force Base near Sooner Road as an F4. The storm damaged and/or destroyed several businesses, homes and churches in Midwest City. Some damage in this area was rated as high-end F4, although F5 was considered. The tornado diminished over Midwest City and finally lifted near the intersection of Reno Avenue and Woodcrest Drive.
Thirty-six people died in this tornado,[16] and over 8,000 homes were badly damaged or destroyed. The tornado caused $1 billion in damage, making it the second-costliest tornado in U.S. history,[17] and the most costly in history from 1999 to 2011, at which point it was surpassed by the2011 Tuscaloosa–Birmingham tornado and again by the2011 Joplin tornado. It was also the deadliest tornado to hit the U.S. since the April 10, 1979F4 tornado that hitWichita Falls, Texas, which killed 42 people.[18]
| Meteorological history | |
|---|---|
| Formed | May 3, 1999, 9:25 p.m.CDT (UTC−05:00) |
| Dissipated | May 3, 1999, 10:45 p.m. CDT (UTC−05:00) |
| Duration | 1 hour, 20 minutes |
| F4 tornado | |
| on theFujita scale | |
| Highest winds | 257 mph (414 km/h) (as measured by mobileDoppler radar) |
| Overall effects | |
| Fatalities | 2 |
| Injuries | 26 |
| Damage | $100 million (1999USD) $188.8 million (2025 USD) |
Late in the evening on May 3 at 9:25 p.m. CDT, a destructive tornado touched down 3 miles (4.8 km) southwest ofCimarron City inLogan County, Oklahoma, eventually hitting the town ofMulhall, located north ofGuthrie.[19] Thiswedge tornado, which tracked a 39-mile (63 km) path, was very wide and at times exceeded one mile (1.6 km) in width. According tostorm chasing meteorologistRoger Edwards, it may have been as violent or more than the F5 Bridge Creek–Moore tornado (however, it was officially rated as an F4).[20]
A Doppler On Wheels (DOW) mobile radar observed this tornado as it crossed Mulhall. The DOW documented the largest-ever-observed core flow circulation with a distance of 1,600 m (5,200 ft) between peak velocities on either side of the tornado, and a roughly 7 km (4.3 mi) width of peak wind gusts exceeding 43 m/s (96 mph), making the Mulhall tornado the largest tornado ever measured quantitatively.[21] The DOW measured a complexmulti-vortex structure,[22] with several vortices containing winds of up to 257 mph (414 km/h) rotating around the tornado. The 3D structure of the tornado has been analyzed in a 2005 article in theJournal of the Atmospheric Sciences by Wen-Chau Lee andJoshua Wurman.[23] The tornado severely damaged or destroyed approximately 60–70% of the 130 homes in Mulhall, destroying the Mulhall/Orlando Elementary School and toppling the city'swater tower.
After the tornado dissipated at approximately 10:45 p.m. CDT in southeasternNoble County, 3 miles (4.8 km) northeast ofPerry, many of the same areas of Logan County struck by the Mulhall tornado were hit again by an F3 tornado. However, this one was produced by a separate supercell that touched down 2.5 miles (4.0 km) south ofCrescent at 10:56 p.m. CDT.[19] Damage caused by this tornado was indistinguishable from damage caused by the earlier F4 tornado. 25 homes were destroyed and 30 others were damaged near Crescent, with much of the damage believed to have been caused by both tornadoes.
| Meteorological history | |
|---|---|
| Formed | May 3, 1999, 10:10 p.m.CDT (UTC−05:00) |
| Dissipated | May 3, 1999, 10:50 p.m. CDT (UTC−05:00) |
| Duration | 40 minutes |
| F3 tornado | |
| on theFujita scale | |
| Overall effects | |
| Injuries | 7 |
At 10:10 p.m. CDT, a damaging tornado touched down 3 miles (4.8 km) north-northeast ofSparks inLincoln County, Oklahoma, with only sporadic tree damage occurring as it tracked north-northeast towardDavenport. Scattered damage of high-end F0 to low-end F1 intensity occurred to some homes and businesses on the southeast side of Davenport, though a house located just south of town lost more than half of its roof. As the tornado continued to track northeast, parallel withInterstate 44 andState Highway 66,Stroud took a direct hit as the storm intensified to F2 strength; the trucking terminal of the Sygma food distribution warehouse on the west side of town was destroyed with some girders and siding from the warehouse thrown northwest acrossState Highway 66, and the Stroud Municipal Hospital suffered significant roof damage, which resulted in significant water damage within the building. The most severe damage, consistent with an F3 tornado, occurred at the Tanger Outlet Mall at 10:39 p.m. CDT with almost all of the stores suffering roof damage at minimum, though sections of seven storefronts were destroyed and the exterior walls of the Levi's store were collapsed inward. The mall was evacuated in advance of the tornado, resulting in no injuries or loss of life in the building. The tornado finally dissipated 1 mile (1.6 km) south of Stroud Lake at 10:50 p.m. CDT.[19]
While there were no fatalities overall in Stroud, the economic impact of the tornado has been compared to the loss of Tinker Air Force Base,General Motors, and a major regional hospital for the Stroud region as compared to Oklahoma City at that time. Approximately 800 jobs were lost in a community of approximately 3,400 people due to the damage of the Sygma distribution warehouse and Tanger Outlet Mall, neither of which were rebuilt.[24] Stroud's recovery was later complicated by theSeptember 11, 2001, terrorist attacks, although the town has since recovered as a result of higher oil and gas prices. Local leading industries include Service King, an oilfield manufacturing facility, and Mint Turbines, a helicopter engine reconditioning facility. Stroud is also now a downloading facility location for oil produced in the northern United States into theCushing pipeline network.
The May 3 tornado event was part of a three-day event that included tornadoes in thestates ofKansas,Texas andTennessee. A deadly F4 tornado that tracked 24 miles (39 km) across south-central Kansas killed six people inHaysville andWichita during the late evening of May 3. Other fatalities during the event included one person killed in Texas on May 4 by an F3 tornado that tracked 71.5 miles (115.1 km) from nearWinfield, Texas, to southwest ofMineral Springs, Arkansas, and three people killed inTennessee on May 5 and 6 by an F4 tornado that struck the town ofLinden.[25]
Flash flooding killed one person inCamden County, Missouri, on May 4.[26] On May 6, lightning struck and killed a man inCobbtown, Georgia.[27]
| Structural damage in Oklahoma[28] | |||
|---|---|---|---|
| Oklahoma and Cleveland counties | Other counties | ||
| Homes destroyed | 1,780 | 534 | |
| Homes damaged | 6,550 | 878 | |
| Businesses destroyed | 85 | 79 | |
| Businesses damaged | 42 | 54 | |
| Public buildings destroyed | 4 | 7 | |
| Apartments destroyed | 473 | 568 | |
On May 3–4, the day after the initial outbreak event,PresidentBill Clinton signed a federal disaster declaration for eleven Oklahoma counties. In a press statement by theFederal Emergency Management Agency (FEMA), then-directorJames Lee Witt stated that "The President is deeply concerned about the tragic loss of life and destruction caused by these devastating storms."[29] TheAmerican Red Cross opened ten shelters overnight, housing 1,600 people immediately following the disaster, decreasing to 500 people by May 5. On May 5, several emergency response and damage assessment teams from FEMA were deployed to the region. TheUnited States Department of Defense deployed the249th Engineering Battalion and placed theU.S. Army Corps of Engineers on standby for assistance. Medical and mortuary teams were also sent by theU.S. Department of Health and Human Services.[30] By May 6, donation centers and phone banks were being established to create funds for victims of the tornadoes.[31] Within the first few days of the disaster declaration, relief funds were sent to families requesting aid. Roughly $180,000 had been approved by FEMA for disaster housing assistance by May 9.[32]
Debris removal began on May 12 as seven cleanup teams were sent to the region with more teams expected to join over the following days.[33] That day, FEMA also granted seven Oklahoma counties (Canadian,Craig, Grady, Lincoln, Logan, Noble and Oklahoma) eligibility for federal financial assistance.[34] Roughly $1.6 million in disaster funds had been approved for housing and business loans by May 13,[35] increasing to more than $5.9 million over the following five days.[36] Applications for federal aid continued through June, with state aid approvals reaching $54 million on June 3. According to FEMA, more than 9,500 Oklahoma residents applied for federal aid during the allocated period in the wake of the tornadoes, including 3,800 in Oklahoma County and 3,757 in Cleveland County. Disaster recovery aid for the tornadoes totaled to roughly $67.8 million by July 2.[37]
| Outbreak death toll | |||
|---|---|---|---|
| State | Fatalities | County | County total |
| Kansas | 6 | Sedgwick | 6 |
| Oklahoma | 40 | Cleveland | 11 |
| Grady | 12 | ||
| Kingfisher | 1 | ||
| Logan | 1 | ||
| McClain | 1 | ||
| Payne | 1 | ||
| Pottawatomie | 1 | ||
| Oklahoma | 12 | ||
| Tennessee | 3 | Perry | 3 |
| Texas | 1 | Titus | 1 |
| Total | 50 | ||
| All deaths were tornado-related | |||
From a meteorological and safety standpoint, the tornado called into question the use of highway overpasses as shelters from tornadoes. Prior to the events on May 3, 1999, videos of people taking shelter in overpasses during tornadoes in the past (such as an infamous video from theApril 26, 1991 tornado outbreak taken by a news crew from Wichita NBC affiliateKSNW) created public misunderstanding and complacency that overpasses provided adequate shelter from tornadoes. Although meteorologists had questioned the safety of these structures for nearly 20 years, there had been no evidence supporting incidents involving loss of life.[38] Three overpasses were directly struck by tornadoes during the May 3 outbreak, resulting in fatalities at each location. Two occurred as a result of the Bridge Creek–Moore F5, while the third occurred in ruralPayne County, which was struck by an F2 tornado.[39] According to a study by the National Oceanic and Atmospheric Administration, seeking shelter in an overpass "is to become a stationary target for flying debris"; the wind channeling effect that occurs within these structures along with an increase in wind speeds above ground level, changing of wind direction when the tornado vortex passes, and the fact most overpasses do not have girders for people to take shelter between also provide little to no protection.[40]
