37°41′24″N 97°08′10″W / 37.69°N 97.136°W / 37.69; -97.136

1991 Andover tornado outbreak
Storm reports on April 26 and early April 27, 1991
Tornado outbreak
Tornadoes55
Maximum ratingF5 tornado
DurationApril 26–27, 1991
Highest winds268 mph (431 km/h), from the Red Rock tornado
Highest gusts100 mph (160 km/h)[1][2]
Largest hail4 in (100 mm)[3]
Overall effects
Fatalities21
Injuries313
Damage$589 million ($1,265,490,000 in 2024 USD)[4][nb 1]
Areas affectedUnited States Great Plains
Part of the tornado outbreaks of 1991

From April 26 to 27, 1991, multiple supercells across Oklahoma and Kansas led to a regional tornado outbreak. Forced by a potent trough and focused along a dryline, these distinct thunderstorms moved northeast through a moist and highly unstable environment. A total of 55 tornadoes were confirmed, many of which were strong, F2 or greater on the Fujita scale. A widely documented F5 tornado tore through Andover, Kansas, killing 17 people. Additional fatalities occurred from significant tornadoes in other portions of Kansas and Oklahoma, with 21 deaths recorded in total. An F4 tornado was detected by a mobile doppler weather radar team which observed winds up to 270 mph (430 km/h) at the top of the funnel, the first time winds of F5 intensity were measured by radar, and the highest winds recorded by radar at the time. A news team filming an F2 tornado sought shelter under a Kansas Turnpike overpass, causing a misconception that overpasses can provide adequate shelter during a tornado. This outbreak occurred within a transition period for the National Weather Service and proved the value of NEXRAD radars, which were utilized in Oklahoma to provide advanced warning to residents.

Meteorological synopsis

Radar animation of supercell thunderstorms across Kansas and Oklahoma

On April 25, 1991, the National Weather Service issued a warning of an impending weather system, noting that computer models were "indicating this to be a very significant severe weather producer with tornadoes occurring across the Central/Southern Plains." On the morning of April 26, the organization delineated a High risk of severe weather across the Great Plains.[5] A southeast-tilted trough existed across the Southwestern United States that morning, and a distinct jet streak, or a region of enhanced winds at the base of the trough, on the order of 75–85 kn (85–100 mph; 140–155 km/h) was progressing northeast toward the Plains.[6][7] Through the morning hours, an 850 mb or approximately 5,000 ft (1,525 m) low-level jet of up to 60 kn (70 mph; 110 km/h) overspread regions from south-central Kansas northward into eastern Nebraska.[8] A surface low-pressure area existed over southwestern Nebraska, supporting a dry line southward into Texas and a warm front southeastward across eastern sections of Kansas and Oklahoma.[5]

In the unstable atmosphere between those two boundaries, surface dewpoints rose above 60 °F (15 °C). Abundant sunshine contributed to destabilization as lifted indices topped -12 from central Oklahoma into central Kansas and convective available potential energy reached 4,000 J/kg.[5] A minimal capping inversion existed across Oklahoma even during the morning hours,[6] and tornado-producing storms first developed across western Oklahoma around sunrise. These storms weakened as they moved northeast into Kansas.[9] Back to the west, the dryline progressed rapidly eastward but began to slow precipitously during the afternoon hours. Attempts at thunderstorm development along this feature initially failed.[5] At 17:10 UTC (12:20 p.m. CDT), the National Weather Service issued a particularly dangerous situation tornado watch, warning of the potential for multiple strong to violent tornadoes. This would be one of 24 convective watches issued during the day.[6] Despite early failure at convective initiation, supercell thunderstorms rapidly erupted along the dryline during the afternoon hours as the jet streak propagated into the Great Plains, resulting in a regional outbreak of tornadoes stretching from Texas to Iowa. Violent tornadoes were concentrated in southern Kansas and Oklahoma, although intense tornadoes were also observed in Iowa, Texas, and Nebraska.[9]

Confirmed tornadoes

Confirmed tornadoes by Fujita rating
FU F0 F1 F2 F3 F4 F5 Total
0 12 13 18 7 4 1 55
List of confirmed tornadoes – Friday, April 26, 1991[nb 2][nb 3]
F# Location County / Parish State Start
coord.		 Time (UTC) Path length Max. width Damage
F2 Tonkawa Kay OK April 26 36°41′N 97°18′W / 36.68°N 97.30°W / 36.68; -97.30 (Tonkawa (Apr. 26, F2)) 11:45 1 mi (1.6 km) 100 yd (91 m)
Two homes sustained severe roof damage, one from tornadic winds and the other from a fallen tree. Fifteen other houses sustained lesser damage. Greenhouses were damaged at a garden center.[11][12]
F2 Cherryvale Montgomery KS April 26 37°16′N 95°33′W / 37.27°N 95.55°W / 37.27; -95.55 (Cherryvale (Apr. 26, F2)) 15:45 6 mi (9.7 km) 100 yd (91 m)
A large building at a nursery/greenhouse complex was destroyed.[11][13]
F2 NW of Washington Washington KS April 26 39°49′N 97°07′W / 39.82°N 97.12°W / 39.82; -97.12 (Washington (Apr. 26, F2)) 20:25 3.5 mi (5.6 km) 100 yd (91 m)
Several farmhouses were destroyed to the northwest of Washington, resulting in the deaths of several hogs. Some damage occurred in the town of Lanham. Six people were injured.[11][14]
F1 Ohiowa Fillmore NE April 26 40°25′N 97°27′W / 40.42°N 97.45°W / 40.42; -97.45 (Ohiowa (Apr. 26, F0)) 20:40–20:45 1 mi (1.6 km) 50 yd (46 m)
Four grain trailers and a grain truck were flipped over. A satellite dish, a barn door, and a separate barn were destroyed. Trees were extensively damaged.[11][15]
F0 N of Strong City Chase KS April 26 38°26′N 96°32′W / 38.43°N 96.53°W / 38.43; -96.53 (Strong City (Apr. 26, F0)) 20:45 1 mi (1.6 km) 17 yd (16 m)
A few farm sheds were damaged.[11][16]
F3 SE of Hollenberg, KS to S of Beatrice, NE Washington (KS), Gage (NE) KS, NE April 26 39°57′N 96°57′W / 39.95°N 96.95°W / 39.95; -96.95 (Hollenberg-Beatrice (Apr. 26, F3)) 20:50–21:40 24 mi (39 km) 200 yd (180 m)
This tornado first touched down in Kansas before moving into Nebraska, where the town of Lanham sustained considerable damage. Farms sustained heavy damage near Odell, and several homes were destroyed south of Beatrice before the tornado dissipated.[11][17][18]
F0 NE of Council Grove Morris, Wabaunsee KS April 26 38°40′N 96°31′W / 38.67°N 96.52°W / 38.67; -96.52 (Council Grove (Apr. 26, F0)) 21:10 13 mi (21 km) 50 yd (46 m)
A weak tornado caused damage to trees, fences, several power poles, and a cabin.[11][19][20]
F2 N of Bushong to NE of Grove Wabaunsee, Shawnee, Jackson KS April 26 38°44′N 96°15′W / 38.73°N 96.25°W / 38.73; -96.25 (Bushong-Grove (Apr. 26, F2)) 21:35 44 mi (71 km) 200 yd (180 m)
In Waubaunsee County, a farmhouse and some other structures were destroyed. An old stone church was damaged. In Shawnee County, the roofs and windows of several houses were damaged in western Rossville. The tornado rapidly weakened in Jackson County.[11][21][22][23]
F2 E of Adams Gage NE April 26 40°26′N 96°30′W / 40.43°N 96.50°W / 40.43; -96.50 (Adams (Apr. 26, F2)) 22:00–22:15 4 mi (6.4 km) 150 yd (140 m)
In conjunction with the Hollenberg–Beatrice F3 tornado, a strong tornado damaged up to 25 farmsteads, including 100 buildings and 30 pieces of large farm equipment.[11][24]
F3 NW of Douglas to NE of Palmyra Otoe NE April 26 40°36′N 96°24′W / 40.60°N 96.40°W / 40.60; -96.40 (Douglas-Palmyra (Apr. 26, F3)) 22:15–22:40 14 mi (23 km) 350 yd (320 m)
Four farms were destroyed and three others were severely damaged. Thirteen houses were damaged as well. Two people were injured.[11][25]
F0 NE of Anthony Harper KS April 26 37°13′N 97°57′W / 37.22°N 97.95°W / 37.22; -97.95 (Anthony (Apr. 26, F0)) 22:20 1 mi (1.6 km) 50 yd (46 m)
Part of a roof was torn off.[11][26]
F0 SE of Freeport to NE of Conway Springs Harper, Sumner KS April 26 37°11′N 97°50′W / 37.18°N 97.83°W / 37.18; -97.83 (Freeport-Conway Springs (Apr. 26, F0)) 22:30 16 mi (26 km) 500 yd (460 m)
A weak tornado skipped across open fields.[11][27][28]
F1 N of Goddard Sedgwick KS April 26 37°40′N 97°35′W / 37.67°N 97.58°W / 37.67; -97.58 (Goddard (Apr. 26, F0)) 22:47 2 mi (3.2 km) 50 yd (46 m)
A boat dealership sustained major damage in Goddard.[11][29]
F5 SE of Clearwater to Andover to NE of El Dorado Lake Sedgwick, Butler KS April 26 37°28′N 97°29′W / 37.47°N 97.48°W / 37.47; -97.48 (Clearwater–Andover–El Dorado Lake (Apr. 26, F5)) 22:57 46 mi (74 km) 700 yd (640 m)
17 deaths – See section on this tornado – 225 people were injured.[30][31]
F3 E of Enid Garfield OK April 26 36°26′N 97°40′W / 36.43°N 97.67°W / 36.43; -97.67 (Enid-Garber (Apr. 26, F3)) 23:00–23:09 6 mi (9.7 km) 350 yd (320 m)
Two homes were destroyed. A pickup truck was rolled 150 yards (140 m) and demolished as well.[11][32]
F1 Valley Center to S of Putnam Sedgwick, Harvey KS April 26 37°50′N 97°23′W / 37.83°N 97.38°W / 37.83; -97.38 (Putnam (Apr. 26, F1)) 23:10 16 mi (26 km) 50 yd (46 m)
No damage information is available for this tornado.[11][33][34]
F0 SW of Plainview Pierce NE April 26 42°17′N 97°49′W / 42.28°N 97.82°W / 42.28; -97.82 (Plainview (Apr. 26, F0)) 23:15 0.1 mi (0.16 km) 20 yd (18 m)
A tornado briefly touched down in an open field.[11][35]
F0 W of Garber Garfield OK April 26 36°26′N 97°36′W / 36.43°N 97.60°W / 36.43; -97.60 (Garfield (Apr. 26, F0)) 23:15 0.1 mi (0.16 km) 20 yd (18 m)
A weak, brief tornado caused only minor damage.[11][36]
F4 E of Garber to NW of Pawhuska Garfield, Noble, Osage OK April 26 36°26′N 97°33′W / 36.43°N 97.55°W / 36.43; -97.55 (Garber-Pawhuska (Apr. 26, F4)) 23:30–00:55 66 mi (106 km) 1,500 yd (1,400 m)
See section on this tornado – Six people were injured.[37][38][39]
F4 W of Arkansas City to NW of Cambridge Cowley KS April 26 37°04′N 97°09′W / 37.07°N 97.15°W / 37.07; -97.15 (Arkansas City-Cambridge (Apr. 26, F4)) 23:30 25 mi (40 km) 1,320 yd (1,210 m)
1 death – A violent tornado leveled homes south of Hackney. A woman was killed near Tisdale when it destroyed her manufactured home, despite advanced warning that a tornado was approaching. A supplementary report by Thomas P. Grazulis in 2001 indicated that least one home may have incurred F5 damage, reportedly being so badly damaged that National Weather Service (NWS) surveyors failed to notice it.[11][40][41][42][43]
F0 W of Alma to N of Paxico Wabaunsee KS April 26 39°01′N 96°21′W / 39.02°N 96.35°W / 39.02; -96.35 (Alma-Paxico (Apr. 26, F0)) 23:35 9 mi (14 km) 20 yd (18 m)
Trees were damaged.[11][44]
F2 Reese Cherokee TX April 26 32°01′N 95°23′W / 32.02°N 95.38°W / 32.02; -95.38 (Reese (Apr. 26, F2)) 00:00–00:01 0.2 mi (0.32 km) 10 yd (9.1 m)
Four houses and two manufactured homes were destroyed, the roofs of additional structures were damaged, trees were uprooted, and television antennas were toppled.[11][45]
F2 NE of El Dorado to E of Matfield Green Butler, Chase KS April 26 37°56′N 96°43′W / 37.93°N 96.72°W / 37.93; -96.72 (El Dorado Lake-Matfield Green (Apr. 26, F2)) 00:10 21 mi (34 km) 100 yd (91 m)
See section on this tornado – Four people were injured.[46][47]
F3 S of Mount Selman Cherokee TX April 26 32°03′N 95°18′W / 32.05°N 95.30°W / 32.05; -95.30 (Mount Selman (Apr. 26, F3)) 00:11–00:16 3 mi (4.8 km) 200 yd (180 m)
An intense tornado destroyed three manufactured homes, two houses, and one vehicle. An additional 25 houses were damaged, and trees were uprooted. Numerous power lines, street signs, and television antennas were blown over. One person was injured.[11][48]
F3 W of Howard to Severy Elk, Greenwood KS April 26 37°28′N 96°25′W / 37.47°N 96.42°W / 37.47; -96.42 (Howard-Severy (Apr. 26, F3)) 00:26 14 mi (23 km) 200 yd (180 m)
1 death – A significant tornado leveled a manufactured home and caused additional damage to homes, outbuildings, fences, and power lines. A woman was killed and her husband seriously injured in the destroyed house.[11][49][50]
F2 SW of Yale Payne OK April 26 36°02′N 96°50′W / 36.03°N 96.83°W / 36.03; -96.83 (Yale (Apr. 26, F2)) 00:38–00:47 6.5 mi (10.5 km) 800 yd (730 m)
This large tornado rolled a dump truck 200 yards (180 m), destroyed a metal shop building and a well-built barn, and caused roof damage to two homes. Trees and power lines were toppled as well.[11][51]
F0 NE of Elmdale Chase KS April 26 38°24′N 96°35′W / 38.40°N 96.58°W / 38.40; -96.58 (Elmdale (Apr. 26, F0)) 00:40 1 mi (1.6 km) 50 yd (46 m)
A farm shed was destroyed.[11][52]
F2 S of Turnertown Smith, Rusk TX April 26 32°11′N 95°01′W / 32.18°N 95.02°W / 32.18; -95.02 (Turnertown (Apr. 26, F2)) 00:40–00:50 3 mi (4.8 km) 100 yd (91 m)
Several trees were uprooted.[11][53][54]
F1 NW of Westphalia Shelby IA April 26 41°44′N 95°25′W / 41.73°N 95.42°W / 41.73; -95.42 (Westphalia (Apr. 26, F1)) 00:44–00:47 2 mi (3.2 km) 45 yd (41 m)
No damage information is available.[11][55]
F2 W of Henderson Rusk TX April 26 32°09′N 94°52′W / 32.15°N 94.87°W / 32.15; -94.87 (Henderson (Apr. 26, F2)) 01:00–01:01 0.2 mi (0.32 km) 10 yd (9.1 m)
A barn and outbuildings were destroyed.[11][56]
F3 Denison to Wall Lake Crawford, Sac IA April 26 42°01′N 95°21′W / 42.02°N 95.35°W / 42.02; -95.35 (Denison (Apr. 26, F3)) 01:00–01:17 23 mi (37 km) 150 yd (140 m)
Several farmsteads were damaged or destroyed. Windows were blown out a house, a tractor-semitrailer truck was overturned, and a pig was killed.[11][57][58]
F4 SW of Terlton to NW of Skiatook Pawnee, Osage OK April 26 36°10′N 96°31′W / 36.17°N 96.52°W / 36.17; -96.52 (Terlton-Skiatook (Apr. 26, F4)) 01:10–01:27 32 mi (51 km) 1,700 yd (1,600 m)
1 death – A violent tornado began near Terlton, inflicting minor to moderate damage to trees, power poles, and a few structures. The tornado then rapidly intensified, sweeping several cars off of the Cimarron Turnpike, resulting in a fatality and five injuries. The tornado then struck the Keystone Airpark, destroying four hangars and seven airplanes. Two of the planes were tossed into trees. The fire station at the airport was completely destroyed, with one fire engine tossed 0.25 miles (0.40 km) into trees across the runway. The tornado then struck Westport, destroying 54 homes, 70 vehicles, 5 manufactured homes, 18 outbuildings, and 3 travel trailers. Another 40 homes, in addition to the Westport community center, were also damaged. The tornado then snapped numerous trees and destroyed a Girl Scouts lodge near Lake Keystone before causing additional severe damage in the Skiatook area, where 32 homes were destroyed and 56 others were damaged. Several boats and a marina were damaged at Skiatook Lake. In total, 24 people were injured.[11][59][60][61]
F1 Henderson Rusk TX April 26 32°09′N 94°48′W / 32.15°N 94.80°W / 32.15; -94.80 (Henderson (Apr. 26, F1)) 01:22–01:23 0.2 mi (0.32 km) 10 yd (9.1 m)
Several trees were snapped or uprooted.[11][62]
F1 Osage Nation Osage OK April 26 36°40′N 96°32′W / 36.67°N 96.53°W / 36.67; -96.53 (Osage Nation (Apr. 26, F1)) 01:27 0.25 mi (0.40 km) 10 yd (9.1 m)
A rope-shaped tornado picked up a car and tossed it 50 feet (15 m). Additional damage occurred to houses and manufactured homes.[11][63]
F0 SW of Derby Sedgwick KS April 26 37°35′N 97°20′W / 37.58°N 97.33°W / 37.58; -97.33 (Derby (Apr. 26, F0)) 01:33 1 mi (1.6 km) 50 yd (46 m)
Several outbuildings were damaged.[11][64]
F3 W of Neal to SE of Virgil Greenwood, Woodson KS April 26 37°45′N 96°05′W / 37.75°N 96.08°W / 37.75; -96.08 (Neal-Virgil (Apr. 26, F3)) 01:35 15 mi (24 km) 50 yd (46 m)
Several houses and other buildings were destroyed. At least 26 power poles were snapped. Trucks and equipment at a rock quarry were severely damaged, and a 35,000–40,000 pounds (16,000–18,000 kg) fuel truck was moved 75 yards (69 m). A farmhouse was lifted, rotated 90 degrees, and set back down. Two tractor-semitrailers were demolished, and fences were downed as well.[11][65][66]
F1 SW of Meriden to SE of Rock Creek Shawnee, Jefferson KS April 26 39°07′N 95°36′W / 39.12°N 95.60°W / 39.12; -95.60 (Meriden-Rock Creek (Apr. 26, F1)) 01:54 11 mi (18 km) 100 yd (91 m)
A tornado formed just north of the local National Weather Service office. It destroyed a manufactured home, resulting in four injuries. It also damaged a power substation, trees, and power lines.[11][67][68]
F2 SW of Milford to SE of Spirit Lake Dickinson IA April 26 43°16′N 95°14′W / 43.27°N 95.23°W / 43.27; -95.23 (Dickinson-Spirit Lake (Apr. 26, F2)) 02:00–02:30 18 mi (29 km) 60 yd (55 m)
Serious damage occurred to both the farm buildings and farmhouses on two farmsteads.[11][69]
F2 E of Copan Washington OK April 26 36°53′N 95°56′W / 36.88°N 95.93°W / 36.88; -95.93 (Copan (Apr. 26, F2)) 02:05–02:20 6 mi (9.7 km) 100 yd (91 m)
1 death – A strong tornado destroyed a convenience store and a bait shop. Other buildings and trees were damaged too. It tossed a car with two women inside 250 yards (230 m) into a field, killing the passenger and critically injuring the driver. Nine other people were injured in Copan.[11][70]
F2 E of Valley Falls to SW of Doniphan Jefferson, Atchison KS April 26 39°21′N 95°25′W / 39.35°N 95.42°W / 39.35; -95.42 (Valley Falls-Doniphan (Apr. 26, F2)) 02:25 25 mi (40 km) 100 yd (91 m)
A strong tornado caused severe damage in the Nortonville area, with 13 homes destroyed. A nursing home and several businesses sustained major damage as well. In Atchison County, a grain elevator was damaged and outbuildings were destroyed. Trees were uprooted along the tornado's path.[11][71][72]
F4 Oologah Rogers OK April 26 36°27′N 95°43′W / 36.45°N 95.72°W / 36.45; -95.72 (Oologah (Apr. 26, F4)) 02:45–02:53 4 mi (6.4 km) 1,300 yd (1,200 m)
Though short-lived, this large and violent tornado devastated the town of Oologah before abruptly dissipating, with 60 homes, 16 trailers, 30 barns, and 16 apartment buildings destroyed. The Oolagah School building was severely damaged. Buses from the school were tossed nearly 1 mi (1.6 km) away, into Fourmile Creek. Several metal high-tension towers were downed. A total of 22 people were injured. On top of the destruction this tornado caused, a downburst that followed the storm caused further damage.[11][59][73][74]
F2 S of Detroit Red River TX April 26 33°38′N 95°16′W / 33.63°N 95.27°W / 33.63; -95.27 (Detroit (Apr. 26, F2)) 03:00–03:01 0.2 mi (0.32 km) 10 yd (9.1 m)
Two manufactured homes and a barn were destroyed. Several homes and two automobiles sustained damage. Trees were uprooted.[11][75]
F1 Chelsea Rogers OK April 26 36°32′N 95°26′W / 36.53°N 95.43°W / 36.53; -95.43 (Chelsea (Apr. 26, F1)) 03:10–03:14 2 mi (3.2 km) 30 yd (27 m)
A rope-like and brief tornado destroyed two houses and two manufactured homes in northwestern Chelsea. Three people suffered minor injuries.[11][59][76]
F1 Helena Andrew MO April 26 39°55′N 94°40′W / 39.92°N 94.67°W / 39.92; -94.67 (Helena (Apr. 26, F1)) 03:15 1.8 mi (2.9 km) 50 yd (46 m)
Power lines and trees were downed along an intermittent path.[11][77]
F1 NW of Bagwell Red River TX April 26 33°40′N 95°10′W / 33.67°N 95.17°W / 33.67; -95.17 (Bagwell (Apr. 26, F1)) 03:19–03:20 0.2 mi (0.32 km) 10 yd (9.1 m)
Trees were uprooted, and a bridge was damaged.[11][78]
F0 W of Coffeyville Montgomery KS April 26 37°02′N 95°44′W / 37.03°N 95.73°W / 37.03; -95.73 (Coffeyville (Apr. 26, F0)) 03:20 1 mi (1.6 km) 50 yd (46 m)
A brief tornado damaged a building.[11][79]
F2 SW of Negley Red River TX April 26 33°45′N 95°05′W / 33.75°N 95.08°W / 33.75; -95.08 (Negley (Apr. 26, F2)) 03:30–03:31 0.2 mi (0.32 km) 10 yd (9.1 m)
A barn was destroyed, a manufactured home was overturned, and several homes were damaged. Numerous trees were uprooted as well.[11][80]
F2 Allerton to Millerton Wayne IA April 26 40°42′N 93°22′W / 40.70°N 93.37°W / 40.70; -93.37 (Allenton-Millerton (Apr. 26, F2)) 04:10–04:22 9 mi (14 km) 60 yd (55 m)
Two tornadoes in Wayne County collectively damaged 25 farmsteads and residences.[11][81]
F2 SE of Sewal to SE of Confidence Wayne IA April 26 40°38′N 93°17′W / 40.63°N 93.28°W / 40.63; -93.28 (Sewal-Confidence (Apr. 26, F2)) 04:10–04:28 15 mi (24 km) 75 yd (69 m)
Two tornadoes in Wayne County collectively damaged 25 farmsteads and residences. A manufactured home was destroyed, and two people were injured.[11][82]
F0 S of Joplin Newton MO April 26 37°02′N 94°31′W / 37.03°N 94.52°W / 37.03; -94.52 (Joplin (Apr. 26, F1)) 04:39 0.25 mi (0.40 km) 50 yd (46 m)
A possible tornado was reported.[11][83]
F1 N of Cosby Andrew MO April 26 39°52′N 94°41′W / 39.87°N 94.68°W / 39.87; -94.68 (Cosby (Apr. 26, F1)) 04:57 1.5 mi (2.4 km) 50 yd (46 m)
Trees and power lines were downed.[11][84]
F0 W of Joplin Jasper MO April 27 37°05′N 94°35′W / 37.08°N 94.58°W / 37.08; -94.58 (Joplin (Apr. 26, F0)) 05:05 0.1 mi (0.16 km) 10 yd (9.1 m)
No damage information is available.[11][85]
F2 SE of Victor Iowa IA April 27 41°42′N 92°18′W / 41.70°N 92.30°W / 41.70; -92.30 (Victor (Apr. 26, F2)) 06:55–07:04 4.5 mi (7.2 km) 50 yd (46 m)
Two tornadoes in Iowa County caused damage to several farmsteads, farm buildings, and a house.[11][86]
F1 N of Detroit Red River TX April 27 33°42′N 95°16′W / 33.70°N 95.27°W / 33.70; -95.27 (Detroit (Apr. 26, F1)) 07:05–07:06 0.2 mi (0.32 km) 10 yd (9.1 m)
The tops were snapped off several large trees.[11][87]
F1 S of Marengo Iowa IA April 27 41°44′N 92°04′W / 41.73°N 92.07°W / 41.73; -92.07 (Marengo (Apr. 26, F1)) 07:09 2 mi (3.2 km) 40 yd (37 m)
Two tornadoes in Iowa County caused damage to several farmsteads, farm buildings, and a house.[11][88]

Haysville–McConnell AFB–Southern Wichita–Andover, Kansas

Haysville–McConnell AFB–Southern Wichita–Andover, Kansas
Severe damage to trees from the tornado
Meteorological history
Duration1 hour and 25 minutes
FormedApril 26, 1991, 5:49 p.m. CDT (UTC−05:00)
DissipatedApril 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
Casualties17 fatalities, 225 injuries
Damage$300 million ($644,560,000 in 2024 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

Red Rock, Oklahoma
Photograph of the tornado
Meteorological history
Duration1 hour and 25 minutes
FormedApril 26, 1991, 6:30 p.m. CDT (UTC−05:00)
DissipatedApril 26, 1991, 7:55 p.m. CDT (UTC−05:00)
F4 tornado
on the Fujita scale
Highest winds268 mph (431 km/h)
Overall effects
Casualties6 injuries
Damage$500,000 ($1,070,000 in 2024 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]

El Dorado Lake–Kansas Turnpike Underpass, Kansas

El Dorado Lake–Kansas Turnpike Underpass, Kansas
Meteorological history
FormedApril 26, 1991, 7:10 p.m. CDT (UTC−05:00)
F2 tornado
on the Fujita scale
Overall effects
Casualties4 injuries
Damage$250,000 ($5,370,000 in 2024 USD)[46]

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]

Aftermath

Outbreak death toll
State Total County County
total
Kansas 19 Butler 13
Cowley 1
Elk 1
Sedgwick 4
Oklahoma 2 Pawnee 1
Washington 1
Totals 21
All deaths were tornado-related

In the wake of the tornado outbreak, Kansas Governor Joan Finney requested that President George H.W. Bush supply Sedgwick, Butler, and Cowley counties with federal disaster aid, a move that the president later approved. Under the $2.6 million program,[103] the Federal Emergency Management Agency (FEMA) paid 75 percent of the cost for disaster cleanup, while the local government paid 15 percent, and the state paid the remaining 10 percent.[104] Oklahoma Governor David Walters likewise requested federal assistance for six counties in his state. American Red Cross and civil defense officials scoured devastated homes and rendered aid to about 370 families affected by the storms.[105] After two Oklahoma counties were not granted disaster assistance, local officials in Garfield and Washington counties criticized FEMA's decision. The organization responded by noting that additional counties could be added to the list in the future but that damage in those counties was marginal for a presidential declaration.[106] Two days later, federal assistance was made available to both counties.[107]

In the Oologah–Talala school district of Oklahoma, which was all but devastated during the tornado outbreak, the Oklahoma State Department of Education voted to forgive the remaining 23 days of classes, the largest number of instructional days forgiven in a single school year on record at the time. Individual student conferences were held at a local church. About 170 construction workers worked double shifts to repair the school grounds, which were tentatively set to reopen on August 12. Of the district's 24 buses, 15 were repaired in the weeks following the tornado outbreak, while 9 were rendered inoperable.[108] The school district reopened on August 15.[109]

The 1991 outbreak occurred during a period of modernization for the National Weather Service and helped highlight the value of radar imagery for detecting tornadoes. In April 1991, the WSR-88D NEXRAD radar in Norman, Oklahoma, was the only radar of its kind with Doppler capabilities, and even then it had not been cleared for use in day-to-day operations. In Oklahoma, the higher resolution radar displayed important storm-scale characteristics such as mesocyclones, some of which were seen over 125 miles (200 km) away in Kansas. For comparison, the outdated radars in that state, though closer, did not depict significant features indicative of an ongoing tornado. Instead, forecasters in Kansas were forced to rely on reports from the public and storm chasers. In an internal assessment of the event, the National Weather Service concluded that "The NWS should continue to implement the Next Generation Radar (NEXRAD) network across the Nation. This event illustrates the usefulness of the WSR-88D velocity fields and better azimuthal resolution reflectivity data." The implementation of these radars have improved tornado lead times in modern years.[110]

The outbreak was featured in two different documentaries: Enemy Wind, a documentary produced by The Weather Channel, and Cyclone, a documentary produced and distributed by National Geographic under its National Geographic Home Video series.

See also

Notes

  1. ↑ All losses are in 1991 USD unless otherwise noted.
  2. ↑ All dates are based on the local time zone where the tornado touched down; however, all times are in Coordinated Universal Time and dates are split at midnight CST/CDT for consistency.
  3. ↑ Prior to 1994, only the average widths of tornado paths were officially listed.[10]

References

  1. ↑ Iowa Event Report: Thunderstorm Wind (Report). National Centers for Environmental Information. 1991. Retrieved April 25, 2022.
  2. ↑ Iowa Event Report: Thunderstorm Wind (Report). National Centers for Environmental Information. 1991. Retrieved April 25, 2022.
  3. ↑ "Storm Events Database for April 26–27, 1991". National Centers for Environmental Information. 1991. Retrieved April 25, 2022.
  4. ↑ "Storm Events Database for April 26–27, 1991". National Centers for Environmental Information. 1991. Retrieved April 25, 2022.
  5. 1 2 3 4 "The Kansas-Oklahoma Tornado Outbreak of April 26, 1991". Oklahoma Climatological Survey. Retrieved April 20, 2022.
  6. 1 2 3 "25th Anniversary of April 26th, 1991 Tornado Outbreak". National Weather Service. National Weather Service in Wichita, Kansas. Retrieved April 20, 2022.
  7. ↑ Cody Moore. "Andover, KS Tornado Outbreak April 26, 1991" (PDF). University of Louisville. Retrieved April 20, 2022.
  8. ↑ Dan McCarthy (April 26, 1991). "Day 1 Convective Outlook". Iowa Environmental Mesonet. Retrieved April 25, 2022.
  9. 1 2 "The April 26, 1991 Great Plains Tornado Outbreak". National Weather Service. National Weather Service in Norman, Oklahoma. Retrieved April 20, 2022.
  10. ↑ Brooks 2004, p. 310.
  11. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 William Angel; Jay Hollifield; Jeanette King; Sara Lackey (April 1991). Storm Data: April 1991 (PDF) (Report). Vol. 33. National Center for Environmental Information. Retrieved April 25, 2022.
  12. ↑ Oklahoma Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  13. ↑ Kansas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  14. ↑ Kansas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  15. ↑ Nebraska Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  16. ↑ Nebraska Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  17. ↑ Kansas Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  18. ↑ Nebraska Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  19. ↑ Kansas Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  20. ↑ Kansas Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  21. ↑ Kansas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  22. ↑ Kansas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  23. ↑ Kansas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  24. ↑ Nebraska Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  25. ↑ Nebraska Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  26. ↑ Kansas Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  27. ↑ Kansas Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  28. ↑ Kansas Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  29. ↑ Kansas Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  30. ↑ Kansas Event Report: F5 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  31. ↑ Kansas Event Report: F5 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  32. ↑ Oklahoma Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  33. ↑ Kansas Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  34. ↑ Kansas Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  35. ↑ Nebraska Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  36. ↑ Oklahoma Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  37. ↑ Oklahoma Event Report: F4 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  38. ↑ Oklahoma Event Report: F4 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  39. ↑ Oklahoma Event Report: F4 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  40. 1 2 3 4 Thomas Grazulis (November 1990). Significant Tornadoes, 1880-1989. Vol. 2. St. Johnsbury, Vermont: Environmental Films. ISBN 1-879362-02-3. Retrieved April 22, 2022 – via Google Books.
  41. ↑ — (2001b). F5-F6 Tornadoes. St. Johnsbury, Vermont: The Tornado Project of Environmental Films. p. 9.
  42. ↑ Kansas Event Report: F4 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  43. ↑ "Review of major tornadoes across south central Kansas on April 26 1991". National Weather Service. National Weather Service in Wichita, Kansas. Retrieved April 22, 2022.
  44. ↑ Kansas Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  45. ↑ Texas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  46. 1 2 3 4 Kansas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  47. ↑ Kansas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  48. ↑ Texas Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  49. ↑ Kansas Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  50. ↑ Kansas Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  51. ↑ Oklahoma Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  52. ↑ Kansas Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  53. ↑ Texas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  54. ↑ Texas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  55. ↑ Iowa Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  56. ↑ Texas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  57. ↑ Iowa Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  58. ↑ Iowa Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  59. 1 2 3 The April 26 Great Plains Tornado Outbreak (Report). NWS Norman. Retrieved February 28, 2022.
  60. ↑ Oklahoma Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  61. ↑ Oklahoma Event Report: F4 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  62. ↑ Texas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  63. ↑ Oklahoma Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  64. ↑ Kansas Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  65. ↑ Kansas Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  66. ↑ Kansas Event Report: F3 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  67. ↑ Kansas Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  68. ↑ Kansas Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  69. ↑ Iowa Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  70. ↑ Oklahoma Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  71. ↑ Kansas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  72. ↑ Kansas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  73. ↑ Oklahoma Event Report: F4 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  74. ↑ Grazulis, Thomas P. (January 1997). Significant Tornadoes Update, 1992–1995. St. Johnsbury, Vermont: The Tornado Project of Environmental Films. p. 1412. ISBN 1-879362-04-X.
  75. ↑ Texas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  76. ↑ Oklahoma Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  77. ↑ Missouri Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  78. ↑ Texas Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  79. ↑ Kansas Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  80. ↑ Texas Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  81. ↑ Iowa Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  82. ↑ Iowa Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  83. ↑ Missouri Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  84. ↑ Missouri Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  85. ↑ Missouri Event Report: F0 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  86. ↑ Iowa Event Report: F2 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  87. ↑ Texas Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  88. ↑ Iowa Event Report: F1 Tornado (Report). National Centers for Environmental Information. 2022. Retrieved April 22, 2022.
  89. 1 2 "Top Ten KS Tornadoes". National Weather Service. National Weather Service in Wichita, Kansas. Retrieved April 23, 2022.
  90. 1 2 3 4 5 "Timeline for supercell that produced the Wichita/Andover Tornado". National Weather Service. National Weather Service in Wichita, Kansas. Retrieved April 23, 2022.
  91. ↑ NWS Wichita [@NWSWichita] (May 3, 2016). "#Andover25th tornado struck Haysville as a strong F2/F3. #Outbreak1991" (Tweet). Retrieved April 23, 2022 – via Twitter.
  92. 1 2 3 "Review of major tornadoes across south central Kansas on April 26 1991". National Weather Service. National Weather Service in Wichita, Kansas. Retrieved April 23, 2022.
  93. ↑ NWS Wichita [@NWSWichita] (May 3, 2016). "When the #Andover25th tornado hit the McConnell AFB, it missed a lineup of B1-B bombers. #Outbreak1991" (Tweet). Retrieved April 23, 2022 – via Twitter.
  94. ↑ NWS Wichita [@NWSWichita] (May 3, 2016). "The #Andover25th damaged/destroyed 9 major facilities causing $62 million in damages. #Outbreak1991" (Tweet). Retrieved April 23, 2022 – via Twitter.
  95. ↑ NWS Wichita [@NWSWichita] (May 3, 2016). "On 4/26/91 @6:30p Tornado warning issued for Andover - tornado sirens in Andover failed #Andover25th #Outbreak1991" (Tweet). Retrieved April 23, 2022 – via Twitter.
  96. 1 2 Centers for Disease Control (CDC) (March 13, 1992). "Tornado Disaster — Kansas, 1991". Morbidity and Mortality Weekly Report. 41 (10): 181–183. JSTOR 23299145. PMID 1538688.
  97. ↑ Craig Torbenson; Sadonia Corns; Jessica Nellis; Keith Wondra (November 28, 2011). Kansas: In the Heart of Tornado Alley. Arcadia Publishing. ISBN 978-1-4396-4193-4. Retrieved April 23, 2022.
  98. ↑ Howard Bluestein; James Ladue; Herbert Stein; Douglas Speheger; Wesley Unruh (August 1, 1993). "Doppler Radar Wind Spectra of Supercell Tornadoes". Monthly Weather Review. 121 (8): 2, 200–2, 222. Retrieved April 25, 2022.
  99. ↑ Grazulis, Thomas P. (2001a). The Tornado: Nature's Ultimate Windstorm. Norman: University of Oklahoma Press. p. 109. ISBN 978-0-8061-3538-0.
  100. ↑ NWS Wichita [@NWSWichita] (May 4, 2016). "On 4/26/91 @7:15p Supercell produced a 4th tornado N of El Dorado Lake & moved NE. #Andover25th #Outbreak1991" (Tweet). Retrieved April 25, 2022 – via Twitter.
  101. ↑ NWS Wichita [@NWSWichita] (May 4, 2016). "On 4/26/91 @ ~7:30p The tornado continued to parallel the KS Turnpike before crossing it south of Cassoday. #Andover25th #Outbreak1991" (Tweet). Retrieved April 25, 2022 – via Twitter.
  102. 1 2 3 "Highway Overpasses as Tornado Shelters: Fallout From the 3 May 1999 Oklahoma/Kansas Violent Tornado Outbreak". National Weather Service. National Weather Service in Norman, Oklahoma. Retrieved April 25, 2022.
  103. ↑ "Governor requests disaster declaration". The Parsons Sun. May 1, 1991. p. 7. Retrieved April 25, 2022 – via Newspapers.com.
  104. ↑ "Bush approves aid for tornado relief". The Iola Register. Vol. 94, no. 176. May 21, 1991. p. 2. Retrieved April 25, 2022 – via Newspapers.com.
  105. ↑ Robby Trammell (April 30, 1991). "Walters Seeks Disaster Relief". The Oklahoman. p. 38. Retrieved April 25, 2022 – via Newspapers.com.
  106. ↑ "Left-Out Counties Told to Cool It". The Oklahoman. May 10, 1991. p. 7. Retrieved April 25, 2022 – via Newspapers.com.
  107. ↑ "Two counties added to disaster aid list". Sapulpa Daily Herald. Vol. 76, no. 205. May 12, 1991. p. 12. Retrieved April 25, 2022 – via Newspapers.com.
  108. ↑ Jim Killackey (May 24, 1991). "Oologah School Aims At August 12 Recovery". The Oklahoman. p. 89. Retrieved April 25, 2022 – via Newspapers.com.
  109. ↑ "Classmates Reunite After April Tornado". The Oklahoman. August 16, 1991. p. 112. Retrieved April 25, 2022 – via Newspapers.com.
  110. ↑ "April 26th, 1991 Plains Tornado Outbreak". National Oceanic and Atmospheric Administration. National Weather Service in Tulsa, Oklahoma. Retrieved April 25, 2022.
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