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The 1999 Oklahoma tornado outbreak was a severe weather event that lasted from May 3 until May 6, 1999 and brought violent storms to Oklahomamarker, Kansasmarker, Arkansasmarker, and Tennesseemarker. This article concentrates on the events on May 3, when 66 tornadoes broke out in Oklahoma and Kansas. The most significant tornado first touched down southwest of Chickasha, Oklahomamarker, and became an F5 before dissipating over Midwest City, Oklahomamarker. The tornado tore through Bridge Creek, Oklahomamarker and Moore, Oklahomamarker, causing $1.1 billion in damage. Forty-eight people perished during the outbreak. This tornadic event ranks in severity with the Palm Sunday tornado outbreak of 1965. With a total of 66 tornadoes, it was the most prolific tornado outbreak in Oklahoma history, although not the deadliest.

Outbreak description

May 3, 1999 started sunny, warm, and humid across the affected region. The Storm Prediction Center in Norman, Oklahomamarker initially issued a "slight risk" for severe weather for most of the state of Oklahoma early that morning. By late morning the latest observations and forecasts began to indicate an increasing likelihood of widespread severe weather, and the SPC upgraded sections of the southern plains to "moderate risk." By 3 p.m. it had become evident that a widespread severe weather event was imminent. Parts of Oklahoma and Kansas were then further upgraded to "high risk". When a "high risk" is issued, this usually indicates the potential for a significant severe weather event, including damaging tornadoes. The SPC issued a tornado watch by mid-afternoon as conditions gathered together for what would be a historic tornado outbreak. By the afternoon the CAPE values reached nearly 6,000 J/kg over the region. Large supercell thunderstorms developed and in the late afternoon through the mid-evening hours of that Monday, tornadoes began to break out across the state.

Confirmed tornadoes

(based on NOAA Storm Data)

The Bridge Creek-Moore F5

Path

most significant tornado of the outbreak touched down just southwest of the community of Ambermarker, Oklahomamarker and headed northeast, parallel to Interstate 44, just after another tornado had passed over the airport in Chickashamarker. (Note: it may be argued that the storms touching down in Chickasha and Amber were the same storm; however, for weather tracking purposes, each touchdown is counted as a separate tornado which is most probable). The storm continued moving northeast, destroying the community of Bridge Creekmarker and crossing I-44 just north of Newcastlemarker.

The tornado then crossed the Canadian River, passing into far southern Oklahoma City. As it passed over Bridge Creekmarker, around 6:54 p.m., a Doppler On Wheels (DOW: Wurman et al. 1997, Wurman 2001) mobile Doppler weather radar detected winds of 301 mph (484 km/h), +/- 20 mph inside the tornado at a height of 32 m AGL (Wurman et al. 2007) (The old record was a 257-268 mph wind measurement from a Doppler weather radar near Red Rock, Oklahomamarker, as reported in a formal publication by Bluestein et al. (1993)). 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 and then passed over the intersection of Shields Boulevard and Interstate 35 and back into Oklahoma Citymarker, crossing Interstate 240 near Bryant Avenue. The storm then turned more northerly, striking parts of Del Citymarker and Tinker Air Force Basemarker near Sooner Road as an F4 before diminishing over Midwest City and finally lifting near the intersection of Reno Avenue and Woodcrest Drive.

Casualties

Thirty-six people died in this tornado. Over 8,000 homes were badly damaged or destroyed and the tornado caused $1.1 billion in damage, making it the single most costly tornado in U.S. history , adjusted for inflation. This was also the deadliest tornado since the April 10, 1979 Wichita Falls, Texas Tornado which killed forty- two. However, early warning saved many lives. Warnings were issued well in advance of the tornado's arrival, and the Oklahoma City broadcast media interrupted programming to follow the storms on radar and even by helicopter. The death toll would, most likely, have been higher if people had not had the benefit of the advance warning. Following the storm, three of the local television stations in Oklahoma City: KOCO-TVmarker, KWTVmarker and KFOR-TVmarker continued coverage of the damaging and deadly tornadoes through May 4.

Impact

Outbreak death toll
State Total County County

total
Kansasmarker 6 Sedgwick 6
Oklahomamarker 40 Clevelandmarker 11
Gradymarker 12
Kingfishermarker 1
Loganmarker 1
McClainmarker 1
Paynemarker 1
Pottawatomiemarker 1
Oklahomamarker 12
Tennesseemarker 3 Perrymarker 3
Texasmarker 1 Titusmarker 1
Totals 50
All deaths were tornado-related


Overpass storm shelter deaths

Three of the deaths reported in the tornado were from people who took shelter underneath overpasses in the area of the path of the Moore-Bridge Creek F5 tornado. The deaths occurred at the 16th Street overpass over Interstate 44 in Newcastle (just east of Bridge Creek), at the Shields Boulevard overpass over Interstate 35 in Moore, and the overpass at mile marker 176.5 on Interstate 35 in rural northwestern Payne Countymarker, west of Stillwater.

Fujita scale

This tornado's remarkable wind speed (at the high extreme of the Fujita Scale's F5) led to much speculation that the scale would be modified to include an F6 category, due to the winds possibly exceeding 319 mph (515 km/h). This speculation ignored the fact that the Fujita scale measures damage rather than windspeed, since the scale was developed prior to the introduction of Doppler weather radar. Windspeed estimates associated with the different categories represent the speeds scientists believe are required to produce that damage rather than the windspeed in that particular storm. The damage caused by an F5-designated tornado leaves very little room for a higher category.

The tornado was the last official F5 to hit the United States with the old Fujita scale rating. The next category 5 tornado occurred on May 4, 2007 in Greensburg, Kansasmarker during the May 2007 Tornado Outbreakmarker and killed 11 people. Since February 1, 2007 the National Weather Service has used the Enhanced Fujita Scale to rate tornadoes, and the Greensburg tornado was recorded as the first EF5 tornado. This tornado however, is not the last category 5 tornado to be rated on the Fujita scale, as Canada still uses the Fujita scale, and a tornado that occurred in Manitoba in 2007 was rated an F5.

Other significant tornadoes

Map of the tornadoes that hit near Oklahoma City.
addition to the devastating F5 tornado that hit the southern suburbs of Oklahoma City, there were numerous other significant tornadoes in the outbreak. An F3 tornado hit the town of Stroudmarker (in between Oklahoma City and Tulsamarker) on Interstate 44, destroying the Tanger Outlet Mall. The mall has not been rebuilt.

An F4 tornado hit the town of Mulhallmarker, north of Guthriemarker, destroying most of the town and even toppling the city's water tower. This wedge tornado was very wide, at times exceeding width of over a mile (1.6 km). According to storm chaser Roger Edwards, it may have been as violent if not even more than the F5 Moore/Bridge Creek tornado. 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 1600 m between peak velocities on either side of the tornado, and a roughly 7 km width of peak wind gusts exceeding 43 m/s, making the Mulhall tornado the largest tornado ever measured quantitatively. The DOW measured a complex multiple vortex structure with several multiple vortices containing winds of up to 115 m/s rotating around the tornado. The 3D structure of the tornado has been analyzed in Lee and Wurman 2005.

One of the final tornadoes in the outbreak almost hit the studios of ABC affiliate KTULmarker-TV in Tulsa, located on Lookout Mountain, a few miles west of the city itself, in the early morning hours of May 4 around 12:15 a.m. CDT. Then chief meteorologist Travis Meyer advised his co-workers to take shelter while still on the air reporting on the approaching tornado. It weakened before reaching the station.

The May 3 tornado event was part of a 3-day event that included tornadoes in the states of Kansasmarker, Texasmarker and Tennesseemarker. A deadly tornado killed six people in Haysvillemarker and Wichitamarker, Kansasmarker, the same day. The event killed 1 person in Texas on May 4 and then killed four in Tennesseemarker on Wednesday and Thursday .

Damage estimates

Note: The following was adapted from public domain, official National Weather Service web sites.

The following is a list of the number of homes and businesses damaged by the tornadoes in the outbreak:

Oklahoma and Cleveland Counties Other Counties
Homes destroyed: 1,780 Homes destroyed: 534
Homes damaged: 6,550 Homes damaged: 878
Businesses destroyed: 85 * Businesses destroyed: 79
Businesses damaged: 42 Businesses damaged: 54
Churches destroyed: 3 Churches destroyed: 2
Schools destroyed: 2

Public buildings destroyed: 4
Public buildings damaged: 7
Apartments destroyed: 473 Apartments damaged: 568
  • Includes 53 stores at the Tanger Outlet Center in Stroud.


Source: National Weather Service Norman, OK Forecast Office.

See also



References

External links




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