Oklahoma Tornado Outbreak

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May 3, 1999, Oklahoma Tornado Outbreak

Oklahoma City NEXRAD image at 7:12 pm. The radar shows a classic hook echo at the location of the Bridge Creek/Moore tornado.

Date of tornado outbreak:

May 3-6, 1999

Duration¹:

~72 hours

Maximum rated tornado²:

F5 tornado

Tornadoes caused:

Damages:

$1.5 billion (2005 USD)

Fatalities:

Areas affected:

Oklahoma, Kansas, Texas, Tennessee

¹Time from first tornado to last tornado
²Most severe tornado damage; see Fujita scale

The May 3, 1999, Oklahoma Tornado Outbreak was the first stage of a severe weather event that lasted from May 3 to May 6 and brought violent storms to Oklahoma, Kansas, Arkansas, and Tennessee. This article concentrates on the events in Oklahoma. On May 3, 66 tornadoes broke out in Oklahoma and Kansas. The most significant tornado first touched down southwest of Chickasha, Oklahoma, and became an F5 before dissipating over Midwest City, Oklahoma. Forty-eight people perished during the outbreak. This tornadic event ranks in severity with The Palm Sunday Tornado Outbreak. With a total of 66 tornadoes, it was the most prolific tornado outbreak in Oklahoma history, although not the deadliest.

1 Outbreak
2 The Moore F5
3 Other Significant Tornadoes
4 Damage Estimates
5 The risk of using overpasses as storm shelters
6 See also
7 External links and sources

[edit] Outbreak

The day started sunny, warm, and humid. The Storm Prediction Center in Norman, Oklahoma issued a "high risk" for severe weather for most of the state of Oklahoma that morning. When a "high risk" is issued, this usually indicates a significant threat for severe thunderstorms and tornadoes including damaging tornadoes. The SPC issued a tornado watch early in the afternoon as conditions gathered together for what would be a historic tornado outbreak. The CAPE values reached nearly 6,000 J/kg during the day.

The beautiful May morning gave way to raging dark skies in the afternoon. 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.

Table of confirmed tornadoes - after surveys by local weather service offices

Confirmed Total	Confirmed F0	Confirmed F1	Confirmed F2	Confirmed F3	Confirmed F4	Confirmed F5
66	33	12	10	7	3	1

(based on NOAA Storm Data)

[edit] The Moore F5

The most significant touched down just southwest of the community of Amber, Oklahoma, and headed northeast, parallel to Interstate 44, just after another tornado had passed over the airport in Chickasha, OK. (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.) The storm continued moving northeast, destroying the community of Bridge Creek and crossing I-44 just north of Newcastle.

The tornado then crossed the Canadian River, passing into far southern Oklahoma City. As it passed over Bridge Creek, Oklahoma, around 7:00 pm, a mobile Doppler radar detected winds of 301 +/- 20 mph [1] inside the tornado. (The old record was a 257-268 mph wind measurement from a Doppler radar near Red Rock, Oklahoma, as reported in a formal publication by Bluesetein 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 City, crossing Interstate 240 near Bryant Avenue. The storm then turned more northerly, striking parts of Del City and Tinker Air Force Base near Sooner Road as an F4 before diminishing over Midwest City and finally lifting near the intersection of Reno Avenue and Woodcrest Drive.

36 people were killed in this tornado. More than 10,500 buildings and 47 businesses were destroyed. This tornado caused $1.1 billion in damage, making it the fourth costliest single tornado in U.S. history. This was the deadliest tornado since the April 10, 1979 Wichita Falls, Texas Tornado which killed 42 people. 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 have been much higher if people had not been warned so far in advance. Following the storm, three of the local television stations in Oklahoma City: KOCO-TV, KWTV and KFOR-TV continued coverage of the damaging and deadly tornadoes throughout the day on May 4th.

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 320 mph. 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 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.

[edit] Other Significant Tornadoes

In 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 Stroud, in-between Oklahoma City and Tulsa on Interstate 44, destroying the Tanger Outlet Mall. The mall has not been rebuilt.

Late in the night of May 3, in the Oklahoma City area, it forced the local CBS affiliate, KWTV, to stop broadcasting for a few moments because a tornado had touched down a half-mile east of the television station.

Another F4 hit the town of Mulhall, north of Guthrie, destroying most of the town and even toppling the city's water tower. This wedge tornado was very wide at times excedeeing well over a mile wide. According to stormchaser Roger Edwards, it may have been as violent if not even more than the F5 Moore/Bridge Creek tornado [2].

One of the final tornadoes in the outbreak almost hit the studios of ABC affiliate KTUL-TV in Tulsa, located on Turkey Mountain, a few miles west of the city itself, in the early morning hours of May 4th around 12:15am 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 actually part of a 3-day event that included tornadoes in Kansas and Texas. A deadly tornado killed six people in Haysville and Wichita, Kansas, the same day. The event killed 1 person in Texas on Tuesday, May 4 and then killed four in Tennessee on Wednesday and Thursday.

[edit] 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--

[edit] The risk of using overpasses as storm shelters

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 (currently closed due to construction), and the overpass at mile marker 176.5 on Interstate 35 in rural northwestern Payne County (west of Stillwater).

The two overpass deaths associated with the Oklahoma City storm occurred when the tornado was at its most violent (i.e. F4 or F5) intensity. However, it is of note that the tornado that caused the fatality at Interstate 35 mile marker 176.5 in Payne County was of F2 intensity when it struck the overpass and was NOT in an urban area. This suggests, contrary to the Kansas Turnpike video (see the El Dorado Lake Tornado), that a tornado need not be a large, violent tornado with a considerable debris cloud to cause fatal injuries to people seeking shelter from storms under overpasses. In addition to the fatal injuries to three people, there were also many severe, potentially life-threatening and gruesome injuries inflicted upon people underneath the overpasses that in some cases has left these people with permanent disabilities.