Английская Википедия:1991 Andover tornado outbreak

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Шаблон:Short description Шаблон:For Шаблон:Coord Шаблон:Infobox weather eventШаблон:Infobox weather event/Tornado outbreak Шаблон:Infobox weather event/Effects Шаблон:Infobox weather event/Footer 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 Шаблон:Convert 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

Файл:1991-04-26 radar animation.gif

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. 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 Шаблон:Convert was progressing northeast toward the Plains. Through the morning hours, an 850 mb or approximately Шаблон:Convert low-level jet of up to Шаблон:Convert overspread regions from south-central Kansas northward into eastern Nebraska. 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.

In the unstable atmosphere between those two boundaries, surface dewpoints rose above Шаблон:Convert. 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. A minimal capping inversion existed across Oklahoma even during the morning hours, and tornado-producing storms first developed across western Oklahoma around sunrise. These storms weakened as they moved northeast into Kansas. 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. 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. 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.

Confirmed tornadoes

List of confirmed tornadoes – Friday, April 26, 1991Шаблон:RefnШаблон:Refn

F#	Location	County / Parish	State	Start Шаблон:Abbr	Time (UTC)	Path length	Шаблон:Abbr width	Damage
color|cat2}}; border-bottom: 1px solid black"| F2	Tonkawa	Kay	OK	Шаблон:Sort	Шаблон:Coord	11:45	Шаблон:Convert	Шаблон:Convert
	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.
color|cat2}}; border-bottom: 1px solid black"| F2	Cherryvale	Montgomery	KS	Шаблон:Sort	Шаблон:Coord	15:45	Шаблон:Convert	Шаблон:Convert
	A large building at a nursery/greenhouse complex was destroyed.
color|cat2}}; border-bottom: 1px solid black"| F2	NW of Washington	Washington	KS	Шаблон:Sort	Шаблон:Coord	20:25	Шаблон:Convert	Шаблон:Convert
	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.
color|cat1}}; border-bottom: 1px solid black"| F1	Ohiowa	Fillmore	NE	Шаблон:Sort	Шаблон:Coord	20:40–20:45	Шаблон:Convert	Шаблон:Convert
	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.
color|storm}}; border-bottom: 1px solid black"| F0	N of Strong City	Chase	KS	Шаблон:Sort	Шаблон:Coord	20:45	Шаблон:Convert	Шаблон:Convert
	A few farm sheds were damaged.
color|cat3}}; border-bottom: 1px solid black"| F3	SE of Hollenberg, KS to S of Beatrice, NE	Washington (KS), Gage (NE)	KS, NE	Шаблон:Sort	Шаблон:Coord	20:50–21:40	Шаблон:Convert	Шаблон:Convert
	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.
color|storm}}; border-bottom: 1px solid black"| F0	NE of Council Grove	Morris, Wabaunsee	KS	Шаблон:Sort	Шаблон:Coord	21:10	Шаблон:Convert	Шаблон:Convert
	A weak tornado caused damage to trees, fences, several power poles, and a cabin.
color|cat2}}; border-bottom: 1px solid black"| F2	N of Bushong to NE of Grove	Wabaunsee, Shawnee, Jackson	KS	Шаблон:Sort	Шаблон:Coord	21:35	Шаблон:Convert	Шаблон:Convert
	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.
color|cat2}}; border-bottom: 1px solid black"| F2	E of Adams	Gage	NE	Шаблон:Sort	Шаблон:Coord	22:00–22:15	Шаблон:Convert	Шаблон:Convert
	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.
color|cat3}}; border-bottom: 1px solid black"| F3	NW of Douglas to NE of Palmyra	Otoe	NE	Шаблон:Sort	Шаблон:Coord	22:15–22:40	Шаблон:Convert	Шаблон:Convert
	Four farms were destroyed and three others were severely damaged. Thirteen houses were damaged as well. Two people were injured.
color|storm}}; border-bottom: 1px solid black"| F0	NE of Anthony	Harper	KS	Шаблон:Sort	Шаблон:Coord	22:20	Шаблон:Convert	Шаблон:Convert
	Part of a roof was torn off.
color|storm}}; border-bottom: 1px solid black"| F0	SE of Freeport to NE of Conway Springs	Harper, Sumner	KS	Шаблон:Sort	Шаблон:Coord	22:30	Шаблон:Convert	Шаблон:Convert
	A weak tornado skipped across open fields.
color|cat1}}; border-bottom: 1px solid black"| F1	N of Goddard	Sedgwick	KS	Шаблон:Sort	Шаблон:Coord	22:47	Шаблон:Convert	Шаблон:Convert
	A boat dealership sustained major damage in Goddard.
color|cat5}}; border-bottom: 1px solid black"| F5	SE of Clearwater to Andover to NE of El Dorado Lake	Sedgwick, Butler	KS	Шаблон:Sort	Шаблон:Coord	22:57	Шаблон:Convert	Шаблон:Convert
	17 deaths – See section on this tornado – 225 people were injured.
color|cat3}}; border-bottom: 1px solid black"| F3	E of Enid	Garfield	OK	Шаблон:Sort	Шаблон:Coord	23:00–23:09	Шаблон:Convert	Шаблон:Convert
	Two homes were destroyed. A pickup truck was rolled Шаблон:Convert and demolished as well.
color|cat1}}; border-bottom: 1px solid black"| F1	Valley Center to S of Putnam	Sedgwick, Harvey	KS	Шаблон:Sort	Шаблон:Coord	23:10	Шаблон:Convert	Шаблон:Convert
	No damage information is available for this tornado.
color|storm}}; border-bottom: 1px solid black"| F0	SW of Plainview	Pierce	NE	Шаблон:Sort	Шаблон:Coord	23:15	Шаблон:Convert	Шаблон:Convert
	A tornado briefly touched down in an open field.
color|storm}}; border-bottom: 1px solid black"| F0	W of Garber	Garfield	OK	Шаблон:Sort	Шаблон:Coord	23:15	Шаблон:Convert	Шаблон:Convert
	A weak, brief tornado caused only minor damage.
color|cat4}}; border-bottom: 1px solid black"| F4	E of Garber to NW of Pawhuska	Garfield, Noble, Osage	OK	Шаблон:Sort	Шаблон:Coord	23:30–00:55	Шаблон:Convert	Шаблон:Convert
	See section on this tornado – Six people were injured.
color|cat4}}; border-bottom: 1px solid black"| F4	W of Arkansas City to NW of Cambridge	Cowley	KS	Шаблон:Sort	Шаблон:Coord	23:30	Шаблон:Convert	Шаблон:Convert
	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.
color|storm}}; border-bottom: 1px solid black"| F0	W of Alma to N of Paxico	Wabaunsee	KS	Шаблон:Sort	Шаблон:Coord	23:35	Шаблон:Convert	Шаблон:Convert
	Trees were damaged.
color|cat2}}; border-bottom: 1px solid black"| F2	Reese	Cherokee	TX	Шаблон:Sort	Шаблон:Coord	00:00–00:01	Шаблон:Convert	Шаблон:Convert
	Four houses and two manufactured homes were destroyed, the roofs of additional structures were damaged, trees were uprooted, and television antennas were toppled.
color|cat2}}; border-bottom: 1px solid black"| F2	NE of El Dorado to E of Matfield Green	Butler, Chase	KS	Шаблон:Sort	Шаблон:Coord	00:10	Шаблон:Convert	Шаблон:Convert
	See section on this tornado – Four people were injured.
color|cat3}}; border-bottom: 1px solid black"| F3	S of Mount Selman	Cherokee	TX	Шаблон:Sort	Шаблон:Coord	00:11–00:16	Шаблон:Convert	Шаблон:Convert
	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.
color|cat3}}; border-bottom: 1px solid black"| F3	W of Howard to Severy	Elk, Greenwood	KS	Шаблон:Sort	Шаблон:Coord	00:26	Шаблон:Convert	Шаблон:Convert
	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.
color|cat2}}; border-bottom: 1px solid black"| F2	SW of Yale	Payne	OK	Шаблон:Sort	Шаблон:Coord	00:38–00:47	Шаблон:Convert	Шаблон:Convert
	This large tornado rolled a dump truck Шаблон:Convert, 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.
color|storm}}; border-bottom: 1px solid black"| F0	NE of Elmdale	Chase	KS	Шаблон:Sort	Шаблон:Coord	00:40	Шаблон:Convert	Шаблон:Convert
	A farm shed was destroyed.
color|cat2}}; border-bottom: 1px solid black"| F2	S of Turnertown	Smith, Rusk	TX	Шаблон:Sort	Шаблон:Coord	00:40–00:50	Шаблон:Convert	Шаблон:Convert
	Several trees were uprooted.
color|cat1}}; border-bottom: 1px solid black"| F1	NW of Westphalia	Shelby	IA	Шаблон:Sort	Шаблон:Coord	00:44–00:47	Шаблон:Convert	Шаблон:Convert
	No damage information is available.
color|cat2}}; border-bottom: 1px solid black"| F2	W of Henderson	Rusk	TX	Шаблон:Sort	Шаблон:Coord	01:00–01:01	Шаблон:Convert	Шаблон:Convert
	A barn and outbuildings were destroyed.
color|cat3}}; border-bottom: 1px solid black"| F3	Denison to Wall Lake	Crawford, Sac	IA	Шаблон:Sort	Шаблон:Coord	01:00–01:17	Шаблон:Convert	Шаблон:Convert
	Several farmsteads were damaged or destroyed. Windows were blown out a house, a tractor-semitrailer truck was overturned, and a pig was killed.
color|cat4}}; border-bottom: 1px solid black"| F4	SW of Terlton to NW of Skiatook	Pawnee, Osage	OK	Шаблон:Sort	Шаблон:Coord	01:10–01:27	Шаблон:Convert	Шаблон:Convert
	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 Шаблон:Convert 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.
color|cat1}}; border-bottom: 1px solid black"| F1	Henderson	Rusk	TX	Шаблон:Sort	Шаблон:Coord	01:22–01:23	Шаблон:Convert	Шаблон:Convert
	Several trees were snapped or uprooted.
color|cat1}}; border-bottom: 1px solid black"| F1	Osage Nation	Osage	OK	Шаблон:Sort	Шаблон:Coord	01:27	Шаблон:Convert	Шаблон:Convert
	A rope-shaped tornado picked up a car and tossed it Шаблон:Convert. Additional damage occurred to houses and manufactured homes.
color|storm}}; border-bottom: 1px solid black"| F0	SW of Derby	Sedgwick	KS	Шаблон:Sort	Шаблон:Coord	01:33	Шаблон:Convert	Шаблон:Convert
	Several outbuildings were damaged.
color|cat3}}; border-bottom: 1px solid black"| F3	W of Neal to SE of Virgil	Greenwood, Woodson	KS	Шаблон:Sort	Шаблон:Coord	01:35	Шаблон:Convert	Шаблон:Convert
	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 Шаблон:Convert fuel truck was moved Шаблон:Convert. A farmhouse was lifted, rotated 90 degrees, and set back down. Two tractor-semitrailers were demolished, and fences were downed as well.
color|cat1}}; border-bottom: 1px solid black"| F1	SW of Meriden to SE of Rock Creek	Shawnee, Jefferson	KS	Шаблон:Sort	Шаблон:Coord	01:54	Шаблон:Convert	Шаблон:Convert
	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.
color|cat2}}; border-bottom: 1px solid black"| F2	SW of Milford to SE of Spirit Lake	Dickinson	IA	Шаблон:Sort	Шаблон:Coord	02:00–02:30	Шаблон:Convert	Шаблон:Convert
	Serious damage occurred to both the farm buildings and farmhouses on two farmsteads.
color|cat2}}; border-bottom: 1px solid black"| F2	E of Copan	Washington	OK	Шаблон:Sort	Шаблон:Coord	02:05–02:20	Шаблон:Convert	Шаблон:Convert
	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 Шаблон:Convert into a field, killing the passenger and critically injuring the driver. Nine other people were injured in Copan.
color|cat2}}; border-bottom: 1px solid black"| F2	E of Valley Falls to SW of Doniphan	Jefferson, Atchison	KS	Шаблон:Sort	Шаблон:Coord	02:25	Шаблон:Convert	Шаблон:Convert
	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.
color|cat4}}; border-bottom: 1px solid black"| F4	Oologah	Rogers	OK	Шаблон:Sort	Шаблон:Coord	02:45–02:53	Шаблон:Convert	Шаблон:Convert
	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 Шаблон:Convert 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.
color|cat2}}; border-bottom: 1px solid black"| F2	S of Detroit	Red River	TX	Шаблон:Sort	Шаблон:Coord	03:00–03:01	Шаблон:Convert	Шаблон:Convert
	Two manufactured homes and a barn were destroyed. Several homes and two automobiles sustained damage. Trees were uprooted.
color|cat1}}; border-bottom: 1px solid black"| F1	Chelsea	Rogers	OK	Шаблон:Sort	Шаблон:Coord	03:10–03:14	Шаблон:Convert	Шаблон:Convert
	A rope-like and brief tornado destroyed two houses and two manufactured homes in northwestern Chelsea. Three people suffered minor injuries.
color|cat1}}; border-bottom: 1px solid black"| F1	Helena	Andrew	MO	Шаблон:Sort	Шаблон:Coord	03:15	Шаблон:Convert	Шаблон:Convert
	Power lines and trees were downed along an intermittent path.
color|cat1}}; border-bottom: 1px solid black"| F1	NW of Bagwell	Red River	TX	Шаблон:Sort	Шаблон:Coord	03:19–03:20	Шаблон:Convert	Шаблон:Convert
	Trees were uprooted, and a bridge was damaged.
color|storm}}; border-bottom: 1px solid black"| F0	W of Coffeyville	Montgomery	KS	Шаблон:Sort	Шаблон:Coord	03:20	Шаблон:Convert	Шаблон:Convert
	A brief tornado damaged a building.
color|cat2}}; border-bottom: 1px solid black"| F2	SW of Negley	Red River	TX	Шаблон:Sort	Шаблон:Coord	03:30–03:31	Шаблон:Convert	Шаблон:Convert
	A barn was destroyed, a manufactured home was overturned, and several homes were damaged. Numerous trees were uprooted as well.
color|cat2}}; border-bottom: 1px solid black"| F2	Allerton to Millerton	Wayne	IA	Шаблон:Sort	Шаблон:Coord	04:10–04:22	Шаблон:Convert	Шаблон:Convert
	Two tornadoes in Wayne County collectively damaged 25 farmsteads and residences.
color|cat2}}; border-bottom: 1px solid black"| F2	SE of Sewal to SE of Confidence	Wayne	IA	Шаблон:Sort	Шаблон:Coord	04:10–04:28	Шаблон:Convert	Шаблон:Convert
	Two tornadoes in Wayne County collectively damaged 25 farmsteads and residences. A manufactured home was destroyed, and two people were injured.
color|storm}}; border-bottom: 1px solid black"| F0	S of Joplin	Newton	MO	Шаблон:Sort	Шаблон:Coord	04:39	Шаблон:Convert	Шаблон:Convert
	A possible tornado was reported.
color|cat1}}; border-bottom: 1px solid black"| F1	N of Cosby	Andrew	MO	Шаблон:Sort	Шаблон:Coord	04:57	Шаблон:Convert	Шаблон:Convert
	Trees and power lines were downed.
color|storm}}; border-bottom: 1px solid black"| F0	W of Joplin	Jasper	MO	Шаблон:Sort	Шаблон:Coord	05:05	Шаблон:Convert	Шаблон:Convert
	No damage information is available.
color|cat2}}; border-bottom: 1px solid black"| F2	SE of Victor	Iowa	IA	Шаблон:Sort	Шаблон:Coord	06:55–07:04	Шаблон:Convert	Шаблон:Convert
	Two tornadoes in Iowa County caused damage to several farmsteads, farm buildings, and a house.
color|cat1}}; border-bottom: 1px solid black"| F1	N of Detroit	Red River	TX	Шаблон:Sort	Шаблон:Coord	07:05–07:06	Шаблон:Convert	Шаблон:Convert
	The tops were snapped off several large trees.
color|cat1}}; border-bottom: 1px solid black"| F1	S of Marengo	Iowa	IA	Шаблон:Sort	Шаблон:Coord	07:09	Шаблон:Convert	Шаблон:Convert
	Two tornadoes in Iowa County caused damage to several farmsteads, farm buildings, and a house.

Haysville–McConnell AFB–Southern Wichita–Andover, Kansas

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. It produced strong F2 to F3 damage in Haysville while growing to a width of about Шаблон:Convert and acquiring multi-vortex characteristics. The tornado crossed the Kansas Turnpike about Шаблон:Convert south of the South Wichita Interchange. 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. 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. 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. As the tornado continued to move toward U.S. Route 54 in Kansas in the direction of Andover, 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.

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. 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. However, 13 people were killed, another 17 were hospitalized, and 9 sustained minor injuries among the group who remained in their structures. Additional homes were swept from their foundations to the west of this park, where the Andover tornado earned its F5 rating. Throughout the city, over 1,500 residences were devastated. 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. Along the tornado's path, 84 frame houses and 14 businesses were leveled. A total of 225 people were injured. 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.

Red Rock, Oklahoma

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 Шаблон:Convert, and reach a maximum width of Шаблон:Convert. The tornado began Шаблон:Convert 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 Шаблон:Convert foundation. It lifted west-northwest of that city. Along the tornado's path across sparsely populated areas, several county roads had portions of their asphalt stripped away. 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 Шаблон:Convert 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.

El Dorado Lake–Kansas Turnpike Underpass, Kansas

Шаблон:Infobox weather eventШаблон:Infobox weather event/TornadoШаблон:Infobox weather event/EffectsШаблон:Infobox weather event/Footer After causing widespread destruction in Andover, the parent supercell continued northeast and produced another strong tornado. This tornado, rated F2, tracked for Шаблон:Convert across Butler and Chase counties in Kansas. It paralleled the Kansas Turnpike for many miles before eventually crossing the road south of Cassoday, tossing vehicles up to Шаблон:Convert away from the turnpike. 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.

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.

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.

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, 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. 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. 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. Two days later, federal assistance was made available to both counties.

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. The school district reopened on August 15.

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 Шаблон:Convert 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.

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.Шаблон:Citation needed

See also

• Tornadoes of 1991
• List of North American tornadoes and tornado outbreaks
• List of Storm Prediction Center high risk days

References

• Шаблон:Cite journal

External links

• Gene Moore's April 26, 1991 Chase Account
• Шаблон:YouTube
• Шаблон:YouTube