1991 Andover tornado outbreak

Haysville–McConnell AFB–Southern Wichita–Andover, Kansas

Severe damage to trees from the tornado
Meteorological history
Duration	1 hour and 25 minutes
Formed	April 26, 1991, 5:49 p.m. CDT (UTC−05:00)
Dissipated	April 26, 1991, 7:14 p.m. CDT (UTC−05:00)
F5 tornado
on the Fujita scale
Highest winds	>261 mph (420 km/h)
Overall effects
Casualties	17 fatalities, 225 injuries
Damage	$300 million ($644,560,000 in 2023 USD)[89]

At 5:49 p.m. CDT (22:49 UTC), the storm which would become the Wichita–Andover tornado began east of Clearwater. At 6:05 p.m. CDT (23:05 UTC), the National Weather Service issued a statement urging residents in Haysville, Derby, and Mulvane to seek shelter. This was succeeded by a tornado warning four minutes later. Around 6:16 p.m. CDT (23:16 UTC), the intensifying tornado began to affect southeastern sections of Wichita and directly struck Haysville.[90] It produced strong F2 to F3 damage in Haysville while growing to a width of about 220 yards (200 m) and acquiring multi-vortex characteristics. The tornado crossed the Kansas Turnpike about 0.5 miles (0.80 km) south of the South Wichita Interchange.[91] In eastern Wichita, some well-built houses in the Greenwich Heights Subdivision were completely leveled, indicative of strong F3 to F4 damage. Four people were killed at this location.[92] At 6:24 p.m. CDT (23:24 UTC), the violent tornado struck the McConnell Air Force Base, where it narrowly missed a lineup of 10 B1-B bombers each worth $280 million and 2 of which were equipped with nuclear warheads.[90][93] Nine major facilities on the base were destroyed, including the officer's club, base hospital, library, and elementary school. In addition, 102 housing units were demolished. No fatalities were recorded there, though 16 people were injured and total losses reached $62 million.[94] As the tornado continued to move toward U.S. Route 54 in Kansas in the direction of Andover,[90] it prompted forecasters to issue a heightened tornado warning alerting residents in Augusta and Andover that a damaging tornado was approaching. Despite this warning, the tornado sirens in Andover failed.[95]

At 6:31 p.m. CDT (23:31 UTC), with the sirens not functional, the police drove through the Golden Spur Mobile Home Park and through the town warning residents to seek shelter. 10 minutes later, the now large wedge-stovepipe hybrid tornado entered southern Andover and began to impact the mobile home park, which ultimately sustained a direct hit.[90] Of the 244 manufactured homes, 205, or about 84 percent of them, were destroyed. Post-storm interviews by health officials found that 339 residents were home during the tornado, of which 146 evacuated, 149 sought refuge in the community shelter, and 38 remained in their homes. No casualties occurred among individuals who fled or utilized the shelter.[96] However, 13 people were killed,[92] another 17 were hospitalized, and 9 sustained minor injuries among the group who remained in their structures.[96] Additional homes were swept from their foundations to the west of this park, where the Andover tornado earned its F5 rating.[92] Throughout the city, over 1,500 residences were devastated.[97] The tornado continued northeast, affecting the outskirts of Towanda. Twenty minutes later, the violent tornado dissipated west of El Dorado and north of the Kansas Turnpike, though the parent supercell later produced additional tornadoes.[90] Along the tornado's path, 84 frame houses and 14 businesses were leveled. A total of 225 people were injured.[40] It was the final Kansas tornado to be given an F5 rating prior to the implementation of the Enhanced Fujita Scale, which was principally used on the Greensburg EF5 tornado on May 4, 2007.[89]

Red Rock, Oklahoma

Photograph of the tornado
Meteorological history
Duration	1 hour and 25 minutes
Formed	April 26, 1991, 6:30 p.m. CDT (UTC−05:00)
Dissipated	April 26, 1991, 7:55 p.m. CDT (UTC−05:00)
F4 tornado
on the Fujita scale
Highest winds	268 mph (431 km/h)
Overall effects
Casualties	6 injuries
Damage	$500,000 ($1,070,000 in 2023 USD)[40]

To the south of several significant supercells in Kansas, another discrete storm produced a tornado at 6:30 p.m. CDT (23:30 UTC) which would reach F4 intensity, track for 66 miles (106 km), and reach a maximum width of 1,500 yards (1,400 m). The tornado began 2.5 miles (4.0 km) east of Garber and continued south of Billings. In this area, it reached F3 intensity, snapping power poles, toppling well pumps, demolishing a house, and destroying oil tanks. As it neared Interstate 35 and crossed into Noble County, the tornado first reached F4 intensity, flattening a house and debarking many trees. In neighboring Osage County, two farms were destroyed before the tornado continued into Osage County. There, it passed west of Pawhuska, toppling an oil rig with an 18-inch (460 mm) foundation. It lifted west-northwest of that city.[11] Along the tornado's path across sparsely populated areas, several county roads had portions of their asphalt stripped away.[40] Near Red Rock the tornado became particularly intense. In this area a University of Oklahoma chase team headed by Howard Bluestein utilized mobile doppler weather radar to analyze the tornado. The radar measured peak winds of 120–125 m/s (270–280 mph; 430–450 km/h) at the top of the tornado's funnel, suggesting the tornado probably had F5 winds close to the ground. At the time, this represented the strongest winds ever measured by radar, including the first measurements of F5 intensity winds.[98][99]

After causing widespread destruction in Andover, the parent supercell continued northeast and produced another strong tornado.[100] This tornado, rated F2, tracked for 21 miles (34 km) across Butler and Chase counties in Kansas.[46] It paralleled the Kansas Turnpike for many miles before eventually crossing the road south of Cassoday,[101] tossing vehicles up to 75 yards (69 m) away from the turnpike.[46] The tornado gained notoriety when a Kansas television crew sought shelter underneath an overpass on the Kansas Turnpike. Video from the crew shows a minivan several hundred yards down the turnpike being rolled multiple times, with other vehicles such as large semi-trailer trucks overturned and severely damaged as well. Alongside the 1979 Wichita Falls F4 tornado, this marked the second prominent example of people seeking refuge from a tornado underneath an overpass. Information from the National Weather Service initially and indirectly contributed to this line of thought as well.[102]

During the 1999 Oklahoma tornado outbreak, the consequences of this practice were realized. On May 3, 1999, there were three locations where a highway overpass was utilized as a shelter from approaching tornadoes, and at all three locations there was at least one fatality. One of these, the 1999 Bridge Creek–Moore tornado, was at violent F4–F5 intensity as impacted the overpass. One incorrect notion from the Kansas Turnpike video was that the film crew was protected by the weaker nature of the tornado as it passed over a primarily rural area, in contrast to the Bridge Creek–Moore tornado. However, another F2 on May 3, 1999, killed one individual, proving that tornadoes of any intensity are capable of killing people harboring under overpasses. In addition to the fatalities, many people who survived these tornadoes nonetheless suffered graphic injuries and sometimes permanent disabilities.[102]

Since the Kansas Turnpike video and events on May 3, meteorologists have strongly advised people to avoid seeking shelter under highway overpasses for many reasons. One, it exposes individuals to flying debris, which is the number one cause of death in tornadoes. Two, the elevated nature of the overpass subjects people to stronger winds than at ground level. Three, overpasses may act to channel and accelerate the wind. Four, many overpasses do not have girders for individuals to hold onto, such as was the case during the Kansas Turnpike video. Fifth, tornadic winds shift directions as the vortex passes, such that people originally protected from winds will still be exposed to its effects following the wind shift. The National Weather Service therefore notes, "seeking shelter under a highway overpass is to become a stationary target for flying debris, with a substantial risk of being blown out and carried by the tornado winds". Lastly, motorists who quickly park their cars under an overpass without pulling over to the side first can cause an unexpected traffic jam, that may slow/strand other drivers due to the risk of collision.[102]