Tornado outbreak of April 9–11, 2011

Tornado outbreak of April 9–11, 2011
NEXRAD loop of storms across eastern Nebraska and western Iowa on April 9.
Meteorological history
DurationApril 9–11, 2011
Tornado outbreak
Tornadoes49 confirmed
Maximum ratingEF4 tornado
Duration54 hours, 31 minutes
Highest windsTornadic – 170 mph (270 km/h)
(Pocahontas, Iowa EF4 on April 9)
Overall effects
Fatalities0
Injuries21
Damage$2.2 billion (2011 USD)
Areas affectedMidwestern United States, Southern United States
Part of the tornado outbreaks of 2011

A tornado outbreak took place on April 9-11, 2011. The outbreak was one of several tornado outbreaks in the United States to take place during the record month of April of that year, 49 tornadoes were produced across the Midwest and Southeast from April 9–11. Widespread damage took place; however, no fatalities resulted from the event due to timely warnings. In Wisconsin, 16 tornadoes touched down, ranking this outbreak as the state's largest April event on record as well as one of the largest single-day events during the course of any year. The strongest tornado of the outbreak was an EF4 tornado that touched down west of Pocahontas, Iowa on April 9, a short-lived satellite to a long-track EF3 tornado. Between 9:56 to 9:58 p.m. CDT (02:56 to 02:58 UTC) that day, five tornadoes were on the ground simultaneously in Pocahontas County, Iowa, all of which were from one supercell thunderstorm. Other tornadoes impacted parts of eastern Kentucky and Tennessee on April 9, hours before the event in Iowa.

Throughout Iowa, damage from the storms was estimated at $78.6 million, much of which likely took place in and around Mapleton, which was struck by an EF3 tornado on April 9.[1] In addition to the tornadoes, Texas experienced a widespread straight-line wind and hail event, leaving $100 million in damage. Overall, losses from the storm system reached $2.2 billion, making it the third of a record sixteen billion dollar disasters in 2011.[2]

Meteorological synopsis

A large storm system with an associated frontal boundary moved northward and eastward across the central United States beginning on April 8. While initial severe weather was limited, a lone supercell broke out ahead of a mesoscale convective system in Pulaski County, Virginia on the eastern end of the warm front that evening. Two tornadoes were confirmed, one of which was an EF2 that caused severe damage in Pulaski, Virginia. Numerous houses were damaged and eight people were injured.[3] An outbreak began across the United States during the afternoon of April 9; supercells developed along the warm front and tracked through parts of Kentucky, Tennessee, Virginia, and North Carolina, generating softball sized hail and eight more tornadoes.[4]

At the same time, a progressive upper-level trough moved east out of the Rocky Mountains and over the Midwest. Owing to early morning thunderstorms, moisture levels in the central Great Plains increased; however, capping in the region would limit daytime activity before atmospheric instability allowed for severe weather. Forecast models indicated that the low-level jetstream would produce significant wind shear, aiding in the formation of possible tornadic supercell thunderstorms, and convective available potential energy (CAPE) values could exceed 3,000 J/kg. In light of this, the Storm Prediction Center (SPC) stated a moderate risk of severe weather for areas around the Minnesota-Iowa border. A slight risk was also defined for a broader region surrounding the moderate as well as a narrow line extending southward to Texas.[5] A warm front began developing along the southeastern side of the low pressure area as it moved over The Dakotas.[6]

During the evening hours of April 9, the SPC issued a tornado watch for western and northern Iowa, eastern Nebraska and southeast South Dakota. Conditions within this region were favorable for the development of multiple tornadic storms and there was a 70 percent chance of multiple touchdowns.[7] Around 22:50 UTC (5:50 p.m. CDT), a strong thunderstorm developed over Burt/Cuming Counties in northeastern Nebraska. This cell slowly tracked east-northeastward and developed into a supercell as it moved into Monona County, Iowa. At 00:20 UTC (7:20 p.m. CDT), a small tornado touched down roughly two miles (3.2 km) southwest of Mapleton. Within minutes, this storm quickly grew and intensified as it moved closer to the city. The tornado passed directly over the city at low-end EF3 strength. Turning northward, the tornado dissipated about one mile (1.6 km) north of Mapleton. A separate EF2 tornado struck the town of Early, where considerable damage occurred to homes and businesses.[8]

Tracking northeastward, the supercell moved into Ida County, another tornado touched down around 01:20 UTC (8:20 p.m. CDT) to the west of Arthur.[4] This storm remained on the ground for eight minutes, during which it damaged a few structures, before dissipating two miles (3.2 km) northwest of Arthur.[9] Around the same time, the cell entered Sac County and the first in a series of multiple tornadoes touched down northwest of Odebolt. Over the following three hours, 14 tornadoes touched down across Sac, Buena Vista, and Pocahontas counties. At 02:08 UTC (9:08 p.m. CST), a 1.5-mile (2.4 km) wide EF3 tornado touched down in northern Sac County. Remaining on the ground for an hour, this tornado meandered along a 30-mile (48 km) path, producing several satellite tornadoes, including a short-lived EF4 tornado west of Pocahontas.[10]

Officials blocked off the town and Governor Terry Branstad issued a disaster proclamation for the town. Early estimates indicated that 60% of the town was damaged and 20% was nearly flattened. Despite the damage, only three people sustained minor injuries.[11]

On April 10, another moderate risk was issued. A PDS Tornado Watch was issued for parts of Minnesota, Michigan, and Iowa, as well as most of Wisconsin. With 16 confirmed tornadoes in Wisconsin, the outbreak ranked as the largest single-day event in April in the state. Severe damage occurred in the towns of Merrill, Kaukauna, and Cottonville.[12] On the evening of April 10, a number of tornado watches and warning were issued stretching from southern Oklahoma to Sault. Ste. Marie, Michigan as well as central Ontario which became Canada's first tornado watch of the season. Thunderstorm watches and warnings were also reported as far away as northern and northwestern Ontario.[13]

Confirmed tornadoes

Confirmed tornadoes by Enhanced Fujita rating
EFU EF0 EF1 EF2 EF3 EF4 EF5 Total
0 12 25 7 4 1 0 49

April 9 event

List of confirmed tornadoes – Saturday, April 9, 2011[nb 1]
EF# Location County / Parish State Start Coord. Time (UTC) Path length Max width Damage
[nb 2]
EF0 W of Valeria Menifee, Wolfe KY 37°50′N 83°37′W / 37.83°N 83.62°W / 37.83; -83.62 (Valeria (Apr. 9, EF0)) 18:00–18:04 0.25 mi (0.40 km) 250 yd (230 m) $10,000
Hundreds of trees were damaged in the Daniel Boone National Forest. The path may have been longer but was unable to be surveyed.[14]
EF0 Valeria Wolfe KY 37°49′50″N 83°30′59″W / 37.8305°N 83.5164°W / 37.8305; -83.5164 (Valeria (Apr. 9, EF0)) 18:05–18:09 0.25 mi (0.40 km) 100 yd (91 m) $30,000
A well-constructed barn lifted and moved, a well-anchored carport was destroyed, and many large trees were twisted or uprooted. Two houses and a vehicle were also damaged.[15]
EF0 Norton Norton (city) VA 36°56′03″N 82°37′58″W / 36.9343°N 82.6329°W / 36.9343; -82.6329 (Norton (Apr. 9, EF0)) 19:45–19:48 0.37 mi (0.60 km) 40 yd (37 m) $50,000
Two old buildings sustained roof damage and partial wall collapse, and several trees were downed.[16]
EF0 Milligan College Carter TN 36°17′50″N 82°19′03″W / 36.2971°N 82.3174°W / 36.2971; -82.3174 (Milligan College (Apr. 9, EF0)) 20:35–20:40 0.89 mi (1.43 km) 50 yd (46 m) $20,000
Several trees were downed in the community of Milligan College, just west of Milligan College.[17]
EF0 NNE of Shelby Cleveland NC 35°22′05″N 81°30′43″W / 35.368°N 81.512°W / 35.368; -81.512 (Shelby (Apr. 9, EF0)) 20:50–20:51 0.53 mi (0.85 km) 75 yd (69 m) $50,000
Two mobile homes were flipped over, injuring three of the occupants in one. Several houses sustained minor structural damage, and other mobile homes received mainly minor underskirting and roof damage. The roof was blown off a vehicle shed, and trees were downed.[18]
EF1 E of Jonesborough Washington TN 36°18′00″N 82°26′03″W / 36.3000°N 82.4341°W / 36.3000; -82.4341 (Jonesborough (Apr. 9, EF1)) 22:00–22:05 3 mi (4.8 km) 150 yd (140 m) $75,000
Three barns were heavily damaged, and numerous trees and power lines were downed.[19]
EF1 Johnson City Washington TN 36°18′13″N 82°23′32″W / 36.3037°N 82.3923°W / 36.3037; -82.3923 (Johnson City (Apr. 9, EF1)) 22:08–22:11 0.61 mi (0.98 km) 100 yd (91 m) $10,000
Several large trees were knocked down.[20]
EF0 NNE of Flag Pond Unicoi TN 36°02′33″N 82°33′24″W / 36.0424°N 82.5568°W / 36.0424; -82.5568 (Flag Pond (Apr. 9, EF0)) 22:15–22:20 1.04 mi (1.67 km) 50 yd (46 m) $15,000
Several trees were downed.[21]
EF3 Mapleton Monona IA 42°09′13″N 95°49′42″W / 42.1535°N 95.8283°W / 42.1535; -95.8283 (Mapleton (Apr. 9, EF3)) 00:20–00:26 3.38 mi (5.44 km) 1,200 yd (1,100 m) Unknown
See section on this tornado – 14 people were injured.[22]
EF1 NW of Ricketts Crawford IA 42°11′44″N 95°38′57″W / 42.1956°N 95.6493°W / 42.1956; -95.6493 (Ricketts (Apr. 9, EF1)) 00:37–00:38 0.69 mi (1.11 km) 75 yd (69 m) $25,000
This tornado, which was produced by the same storm as the Mapleton EF3 tornado, knocked down power lines.[23]
EF2 W of Arthur Ida IA 42°19′18″N 95°23′49″W / 42.3217°N 95.3969°W / 42.3217; -95.3969 (Arthur (Apr. 9, EF2)) 01:20–01:28 4.13 mi (6.65 km) 440 yd (400 m) $50,000
This tornado occurred between Arthur and Ida Grove, where two grain bins and two outbuildings on a farmstead were either heavily damaged or destroyed, and a house and garage sustained shingle damage. Several trees were downed, and power poles and lines were damaged.[24]
EF3 NW of Odebolt to E of Schaller Sac IA 42°21′18″N 95°17′10″W / 42.3549°N 95.2860°W / 42.3549; -95.2860 (Odebolt (Apr. 9, EF3)) 01:23–01:55 10.14 mi (16.32 km) 1,760 yd (1,610 m) $2,000,000
A large wedge tornado damaged or destroyed several houses and downed power lines. It initially moved northeast toward Early before making a sharp turn north-northwest to just east of Schaller. This tornado occurred simultaneously to and just west of the following tornado.[25][26]
EF2 N of Odebolt to N of Early Sac IA 42°22′29″N 95°14′33″W / 42.3746°N 95.2424°W / 42.3746; -95.2424 (Odebolt (Apr. 9, EF2)) 01:29–01:54 8.34 mi (13.42 km) 660 yd (600 m) $1,000,000
Numerous houses were damaged or destroyed. The tornado dissipated immediately after passing through Early.[25][27]
EF0 SSW of Early Sac IA 42°23′41″N 95°12′10″W / 42.3948°N 95.2027°W / 42.3948; -95.2027 (Early (Apr. 9, EF2)) 01:38–01:40 0.75 mi (1.21 km) 100 yd (91 m) $1,000
This tornado formed as a satellite to the previous tornado. It executed a brief loop and then moved due north before dissipating. It remained primarily over open country.[25][28]
EF1 S of Galva Ida IA 42°26′11″N 95°27′00″W / 42.4364°N 95.4499°W / 42.4364; -95.4499 (Galva (Apr. 9, EF1)) 01:42–01:47 4.21 mi (6.78 km) 200 yd (180 m) $100,000
A farmstead was severely damaged, with numerous outbuildings destroyed and a home losing its roof. Outbuildings at another farmstead were damaged, as was an outbuilding at an ethanol plant. At least five power poles were snapped, and trees were downed as well.[29]
EF3 NNE of Early to NW of Pocahontas Sac, Buena Vista, Pocahontas IA 42°31′09″N 95°07′45″W / 42.5191°N 95.1291°W / 42.5191; -95.1291 (Sac Co.–Pocahontas Co. (Apr. 9, EF3)) 02:08–03:07 29.37 mi (47.27 km) 2,640 yd (2,410 m) $13,000,000
See section on this tornado – A very large and long lived wedge tornado traversed through three counties, causing severe damage to several farmsteads and the communities of Varina and Ware.[30]
EF0 S of Sulphur Springs Buena Vista IA 42°35′N 95°05′W / 42.58°N 95.09°W / 42.58; -95.09 (Sulphur Springs (Apr. 9, EF0)) 02:14–02:15 0.53 mi (0.85 km) 50 yd (46 m) $0
This brief tornado occurred just a few miles north of the long-track EF3 tornado that began at 02:08 UTC. No damage was reported.[31]
EF1 SSE of Cherokee Cherokee IA 42°36′24″N 95°32′37″W / 42.6067°N 95.5435°W / 42.6067; -95.5435 (Cherokee (Apr. 9, EF1)) 02:20–02:30 5.17 mi (8.32 km) 300 yd (270 m) $100,000
Several outbuildings were damaged or destroyed on two farmsteads, a camper was flipped into a garage, causing damage to both, a large anchored empty tank was flipped, and several buildings in a livestock confinement area were heavily damaged. A house sustained roof damage and broken windows, a grain bin was blown into a semi truck, and a semi trailer was flipped onto another grain bin. Several trees were snapped or uprooted, corn stubble was scoured, and power poles and lines were damage.[32]
EF2 SE of Newell Sac, Buena Vista IA 42°33′20″N 94°58′28″W / 42.5556°N 94.9744°W / 42.5556; -94.9744 (Newell (Apr. 9, EF2)) 02:24–02:27 1.6 mi (2.6 km) 220 yd (200 m) $510,000
See section on this tornado – First satellite tornado of the EF3 tornado that touched down at 02:08 UTC.[25][33]
EF1 ESE of Newell Buena Vista IA 42°34′30″N 94°56′38″W / 42.5751°N 94.9438°W / 42.5751; -94.9438 (Newell (Apr. 9, EF1)) 02:25–02:27 1.08 mi (1.74 km) 150 yd (140 m) $10,000
Several outbuildings and farm structures were damaged. This tornado tracked over the same track of the EF3 tornado that began at 02:08 UTC.[34]
EF0 SW of Alta Buena Vista IA 42°38′N 95°20′W / 42.64°N 95.34°W / 42.64; -95.34 (Alta (Apr. 9, EF0)) 02:50–02:51 0.17 mi (0.27 km) 50 yd (46 m) $0
A storm chaser reported two simultaneous brief tornadoes with no damage.[35]
EF0 SW of Alta Buena Vista IA 42°39′N 95°21′W / 42.65°N 95.35°W / 42.65; -95.35 (Alta (Apr. 9, EF0)) 02:50–02:51 0.17 mi (0.27 km) 50 yd (46 m) $0
A storm chaser reported two simultaneous brief tornadoes with no damage.[36]
EF4 W of Pocahontas Pocahontas IA 42°43′45″N 94°51′21″W / 42.7293°N 94.8557°W / 42.7293; -94.8557 (Pocahontas (Apr. 9, EF4)) 02:54–03:01 3.2 mi (5.1 km) 587 yd (537 m) $2,500,000
See section on this tornado – Second satellite tornado of the EF3 tornado that touched down at 02:08 UTC. One farmstead was completely devastated by this violent tornado.[25][37][38]
EF1 WSW of Pocahontas Pocahontas IA 42°41′22″N 94°48′51″W / 42.6895°N 94.8141°W / 42.6895; -94.8141 (Pocahontas (Apr. 9, EF1)) 02:55–02:58 1.58 mi (2.54 km) 100 yd (91 m) $10,000
See section on this tornado – Third satellite tornado of the EF3 tornado that touched down at 02:08 UTC. This was the cyclonic counterpart of the following, fourth satellite tornado.[25][39]
EF1 WSW of Pocahontas Pocahontas IA 42°41′28″N 94°48′51″W / 42.6912°N 94.8141°W / 42.6912; -94.8141 (Pocahontas (Apr. 9, EF1)) 02:55–02:58 1.64 mi (2.64 km) 100 yd (91 m) $10,000
See section on this tornado – Fourth satellite tornado of the EF3 tornado that touched down at 02:08 UTC. This was the anticyclonic counterpart of the previous, third satellite tornado.[25][40]
EF2 W of Pocahontas Pocahontas IA 42°42′38″N 94°48′52″W / 42.7105°N 94.8144°W / 42.7105; -94.8144 (Pocahontas (Apr. 9, EF2)) 02:56–02:58 0.9 mi (1.4 km) 146 yd (134 m) $100,000
See section on this tornado – Fifth satellite tornado of the EF3 tornado that touched down at 02:08 UTC. This tornado was quickly absorbed by the second, violent EF4 satellite tornado.[25][41]
EF1 WNW of Pocahontas Pocahontas IA 42°44′02″N 94°44′39″W / 42.7340°N 94.7442°W / 42.7340; -94.7442 (Pocahontas (Apr. 9, EF1)) 03:08–03:13 2.42 mi (3.89 km) 250 yd (230 m) $10,000
One house was damaged as the tornado remained over mostly open fields. This tornado occurred east of the track of the 02:08 UTC EF3 tornado that had just dissipated to the northwest.[25][42]
EF1 WNW of St. Joseph Kossuth IA 42°55′23″N 94°16′38″W / 42.9231°N 94.2771°W / 42.9231; -94.2771 (St. Joseph (Apr. 9, EF1)) 04:19–04:21 0.79 mi (1.27 km) 100 yd (91 m) $150,000
A hog barn was damaged, numerous windows were blown out, and a shed was partially collapsed.[25]

April 10 event

List of confirmed tornadoes – Sunday, April 10, 2011[nb 1]
EF# Location County / Parish State Start Coord. Time (UTC) Path length Max width Damage
[nb 2]
EF1 SW of Augusta Eau Claire WI 44°38′N 91°11′W / 44.63°N 91.19°W / 44.63; -91.19 (Augusta (Apr. 10, EF1)) 21:57–22:03 1.58 mi (2.54 km) 200 yd (180 m) $200,000
Two farmsteads were impacted, with many trees downed. At one, a garage was destroyed, and a barn was heavily damaged as well. This was the earliest tornado to touch down in Eau Claire County on record; the previous earliest was May 10.[43]
EF1 NW of Augusta Eau Claire WI 44°41′N 91°08′W / 44.69°N 91.14°W / 44.69; -91.14 (Augusta (Apr. 10, EF1)) 22:04–22:06 0.74 mi (1.19 km) 150 yd (140 m) $250,000
Two outbuildings destroyed, three more were heavily damaged, and numerous trees and power poles were snapped.[44]
EF3 N of Hamburg to NE of Merrill Marathon, Lincoln WI 45°06′41″N 89°53′09″W / 45.1113°N 89.8858°W / 45.1113; -89.8858 (Merrill (Apr. 10, EF3)) 23:08–23:41 21.15 mi (34.04 km) 1,050 yd (960 m) $11,158,000
Severe damage occurred on the north side of Merrill, especially at and around the Merrill Municipal Airport, where hangars and airplanes were destroyed. Throughout Merrill, 65 houses and 12 businesses were damaged or destroyed, with several homes losing nearly all exterior and some interior walls. One person was thrown 200 feet (61 m) after the tornado destroyed his home; he sustained serious injuries. Another person sustained minor injuries. An industrial park sustained heavy damage, and a few other homes and barns were damaged outside of Merrill. Many trees were downed along the path as well.[45][46][47]
EF2 W of Arkdale to ENE of Cottonville Adams WI 44°01′18″N 89°57′18″W / 44.0216°N 89.9549°W / 44.0216; -89.9549 (Cottonville (Apr. 10, EF2)) 23:12–23:30 17.08 mi (27.49 km) 800 yd (730 m) $3,300,000
Numerous houses sustained roof and structural damage, and mobile homes were either heavily damaged or destroyed, along with barns and sheds. A camping trailer was also overturned and sheet metal was wrapped around trees. A lake association building was completely destroyed, a cement silo was knocked over, vehicles were flipped, and numerous center-pivot irrigation systems were twisted or destroyed. Numerous trees were downed along the path.[45][48][49]
EF1 S of Necedah Juneau WI 43°59′43″N 90°05′37″W / 43.9954°N 90.0936°W / 43.9954; -90.0936 (Necedah (Apr. 10, EF1)) 23:14–23:21 4.37 mi (7.03 km) 150 yd (140 m) $30,000
A mobile home was rolled over, and pine trees were snapped.[50]
EF1 SW of Hancock Adams, Waushara WI 44°04′31″N 89°37′06″W / 44.0754°N 89.6184°W / 44.0754; -89.6184 (Hancock (Apr. 10, EF1)) 23:30–23:42 11.73 mi (18.88 km) 140 yd (130 m) $601,000
Several houses sustained roof damage, the roof was torn off a mobile home, and several center-pivot irrigation systems were destroyed. Trees and power poles were downed as well.[51]
EF1 SE of Parrish Langlade WI 45°20′59″N 89°22′56″W / 45.3496°N 89.3822°W / 45.3496; -89.3822 (Parrish (Apr. 10, EF1)) 23:50–23:58 5.3 mi (8.5 km) 400 yd (370 m) $1,000,000
This tornado produced extensive tree damage along the path, affecting over 1,600 acres (6.5 km2) and knocking down or damaging over one million trees. One cabin was destroyed by falling trees.[52]
EF1 Saxeville to Fremont to SE of Hortonville Waushara, Waupaca, Outagamie WI 44°10′07″N 89°08′08″W / 44.1687°N 89.1356°W / 44.1687; -89.1356 (Saxeville (Apr. 10, EF1)) 00:06–00:43 27.68 mi (44.55 km) 200 yd (180 m) Unknown
Multiple barns and other farm buildings were heavily damaged or destroyed, and highway signs were damaged. The roof was torn off a house in Readfield, and the steeple was torn off a church. Many trees were snapped or uprooted along the path.[53]
EF2 SE of Argonne to SE of Popple River Forest, Florence WI 45°38′19″N 88°49′24″W / 45.6386°N 88.8233°W / 45.6386; -88.8233 (Argonne (Apr. 10, EF2)) 00:30–00:51 11.97 mi (19.26 km) 600 yd (550 m) $215,000
Hundreds of trees were snapped or uprooted, some of which fell on cabins. A roof was torn off of a home, several barns and garages were destroyed, and power lines were downed as well.[54]
EF1 Poy Sippi to W of Winchester Waushara, Winnebago WI 44°07′58″N 89°00′16″W / 44.1327°N 89.0045°W / 44.1327; -89.0045 (Poy Sippi (Apr. 10, EF1)) 00:53–01:07 14.93 mi (24.03 km) 150 yd (140 m) $1,470,000
Near Poy Sippi, a house was damaged, and a barn was destroyed. Along the north shore of Lake Poygan, another barn was flattened. Near Boom Bay in Winnebago County, two homes lost portions of their roofs, while several other houses sustained minor damage. Two small mobile homes were rolled as well. Many trees were snapped or uprooted along the path.[55]
EF1 W of Armstrong Creek Forest WI 45°39′00″N 88°31′31″W / 45.6500°N 88.5253°W / 45.6500; -88.5253 (Armstrong Creek (Apr. 10, EF1)) 01:03–01:08 3.29 mi (5.29 km) 250 yd (230 m) $50,000
A garage was destroyed, and two houses were damaged, one of which sustained significant roof damage. Many trees were snapped or uprooted as well.[56]
EF0 SE of Berlin Green Lake WI 43°55′11″N 88°54′47″W / 43.9198°N 88.9130°W / 43.9198; -88.9130 (Berlin (Apr. 10, EF0)) 01:27–01:29 1.83 mi (2.95 km) 50 yd (46 m) $300
Lawn furniture was sucked from under a porch and thrown against a fence, an outdoor spa was damaged, and a wooden structure received light damage. Trees and tree branches were snapped as well.[57]
EF2 Kaukauna Outagamie WI 44°15′28″N 88°17′17″W / 44.2578°N 88.2881°W / 44.2578; -88.2881 (Kaukauna (Apr. 10, EF2)) 01:43–01:46 1.52 mi (2.45 km) 175 yd (160 m) $6,700,000
Over 180 houses were impacted in Kaukauna, several of them losing large sections of their roofs. In total, seven homes were destroyed, 24 homes and four businesses sustained major damage, and 160 other homes sustained minor damage. A church sustained roof damage and had air conditioning units torn off, and large trees were snapped or uprooted.[58]
EF1 S of Greenleaf Brown WI 44°15′28″N 88°17′17″W / 44.2578°N 88.2881°W / 44.2578; -88.2881 (Greenleaf (Apr. 10, EF1)) 01:53–01:55 1.2 mi (1.9 km) 75 yd (69 m) $15,000
The tops of two silos were damaged, and a barn roof was ripped off.[59]
EF1 S of Stockbridge Calumet WI 44°02′16″N 88°19′17″W / 44.0378°N 88.3214°W / 44.0378; -88.3214 (Stockbridge (Apr. 10, EF1)) 01:59–02:01 1.67 mi (2.69 km) 100 yd (91 m) $100,000
A waterspout moved onshore from Lake Winnebago and damaged two homes. A three-season room on one of the houses was ripped off the structure. It also tore off a section of the roof of a large metal outbuilding and snapped the tops of trees.[60]
EF0 NNE of Rogersville Webster MO 37°09′N 93°04′W / 37.15°N 93.06°W / 37.15; -93.06 (Rogersville (Apr. 10, EF0)) 03:55–04:03 6.67 mi (10.73 km) 100 yd (91 m) $10,000
Outbuildings were damaged, and trees were downed.[61]

April 11 event

List of confirmed tornadoes – Monday, April 11, 2011[nb 1]
EF# Location County / Parish State Start Coord. Time (UTC) Path length Max width Damage
[nb 2]
EF1 NNW of Rio Vista Johnson TX 32°16′13″N 97°24′57″W / 32.2702°N 97.4159°W / 32.2702; -97.4159 (Rio Vista (Apr. 11, EF1)) 06:09–06:13 1.51 mi (2.43 km) 100 yd (91 m) $150,000
Five houses were damaged, one of them heavily, and a wall was torn from a pharmacy. A garage was shifted off its foundation, and several trees were downed.[62]
EF1 Alvarado Johnson TX 32°24′51″N 97°13′59″W / 32.4143°N 97.2330°W / 32.4143; -97.2330 (Alvarado (Apr. 11, EF1)) 06:22–06:23 0.13 mi (0.21 km) 50 yd (46 m) $100,000
Five commercial buildings were damaged, and a mobile home was flipped. Two people were injured.[63]
EF1 Northern Forney Kaufman TX 32°46′20″N 96°28′18″W / 32.7721°N 96.4716°W / 32.7721; -96.4716 (Forney (Apr. 11, EF1)) 07:13–07:17 0.53 mi (0.85 km) 60 yd (55 m) $60,000
Five houses sustained roof damage, and a truck stop sign was blown over.[64]
EF1 Cash to NW of Lone Oak Hunt TX 32°59′20″N 96°06′45″W / 32.9888°N 96.1126°W / 32.9888; -96.1126 (Cash (Apr. 11, EF1)) 07:34–07:48 6.53 mi (10.51 km) 200 yd (180 m) $250,000
Eight homes, a pipe manufacturing plant, and two metal buildings were damaged in Cash, while four U-Haul trailers were blown across the highway. Several more homes sustain mainly minor roof damage to the northeast of Cash, although one home sustained significant damage to the roof and second story. Northwest of Lone Oak, five mobile homes were damaged or destroyed, and another site-built home sustained significant damage. Trees were downed along the path.[65]
EF1 Vestavia Hills Jefferson AL 33°26′59″N 86°47′18″W / 33.4496°N 86.7883°W / 33.4496; -86.7883 (Vestavia Hills (Apr. 11, EF1)) 00:30–00:31 0.38 mi (0.61 km) 100 yd (91 m) $65,000
This brief tornado was embedded in a larger microburst. Several homes and other buildings were damaged, mostly by falling trees, and the windows were blown out of a vehicle. Numerous trees were snapped or uprooted as well.[66]

Mapleton, Iowa

Mapleton, Iowa
Damage from the Mapleton, Iowa tornado.
Meteorological history
FormedApril 9, 2011
7:20 p.m. CDT (UTC−05:00)
DissipatedApril 9, 2011
7:26 p.m. CDT (UTC−05:00)
Duration6 minutes[22]
EF3 tornado
on the Enhanced Fujita scale
Max width1,200 yards (0.68 mi; 1.1 km)
Path length3.38 miles (5.44 km)
Highest winds155 mph (249 km/h)
Overall effects
Fatalities0
Injuries14
DamageUnknown
Areas affectedCity of Mapleton and surrounding areas

Prior to the first tornado of the evening in Iowa on April 9, a tornado warning was issued by the National Weather Service in Omaha, Nebraska at 7:08 p.m. CDT (12:08 UTC) for northeastern Monona County.[67] Approximately 16 minutes later, a tornado touched down 1.84 miles (2.96 km) southwest of Mapleton.[22][68]

This large, powerful and dusty tornado began at EF0 intensity, near IA 175. The tornado then steadily increased to EF1 intensity as it moved along the highway, just a few minutes before impacting the southwest side of Mapleton. Trees along this stretch of the highway were snapped or uprooted as the tornado encroached on the Maple River.[22][68]

After causing another instance of EF0 tree damage along 1st Street, the tornado intensified further and entered the city, causing EF2 damage to multiple metal buildings, with many of them buckling and collapsing as the winds passed through. Along South 1st Street, the tornado caused one localized spot of EF3 damage, as a metal auto service was completely collapsed and destroyed, with the steel beams blown over to the next city block. Moving up through much of the center of town, a brick building in the main part of Mapleton, right on the northwestern side of the intersection of Courtright and South 4th Streets was collapsed at EF2 intensity, as the large and damaging wedge tornado went through downtown before weakening.[22][68]

The tornado would exit the through the north side of the city, having only done EF1 damage to several structures and trees, before soon dissipating 1 mile (1.6 km) north of Mapleton.[22][68]

The intense EF3 tornado that struck Mapleton, while despite not the strongest of the evening, was the most notable event of April 9. Widespread damage occurred by this large wedge tornado, which destroyed 100 homes. Residents before the tornado struck received early warning of, and thus has this resulted in no deaths and 14 insignificant injuries, though one person suffered from a broken leg.[22][69] Much of the early warning was helped by storm chasers and spotters, giving many residents around 15 minutes of lead time to take cover before the tornado struck Mapleton.[70]

Nemaha–Varina–Ware, Iowa

Nemaha–Varina–Ware, Iowa
The EF3 tornado (right) seen in Pocahontas County alongside a satellite tornado (left).
Meteorological history
FormedApril 9, 2011
9:08 p.m. CDT (UTC−05:00)
DissipatedApril 9, 2011
10:07 p.m. CDT (UTC−05:00)
Duration59 minutes[30]
EF3 tornado
on the Enhanced Fujita scale
Max width2,640 yards (1.50 mi; 2.41 km)
Path length29.37 miles (47.27 km)
Highest winds145 mph (233 km/h)
Satellite tornadoes
Tornadoes5 confirmed
Maximum ratingEF4 tornado
Highest winds170 mph (270 km/h)
Overall effects
Fatalities0
Injuries0
Damage$16.12 million (2011 USD)
[30][33][38][40][39][41]
(Parent and satellite tornadoes)
Areas affectedSac, Buena Vista and Pocahontas counties; particularly Varina and Ware

Later after dusk settled, the supercell which produced the Mapleton tornado, and a few large and strong tornadoes, dropped this massive and long-lived EF3 wedge tornado at 9:08 p.m. CDT (02:08 UTC) to the west of Nemaha in northern Sac County, following the dissipation of an EF2 tornado that went through the small city of Early. The massive tornado at this point, reached a width of 2,200 yards (1.3 mi; 2.0 km) as it damaged one farmstead at EF2 intensity along an 8.42 mi (13.55 km) path within Sac County.[30][68]

After exiting Sac County into Buena Vista County, a narrow EF2 satellite tornado developed at 9:24 p.m. CDT (02:24 UTC) on the east flank of the main tornado tornado, south of the Sac-Buena Vista County line. This tornado, with estimated winds of 115 mph (185 km/h) lasted for 3 minutes, but damaged trees and buildings on a farm before dissipating along a 1.6 mi (2.6 km) path, and causing $510,000 USD in damage to the property.[33][25] The wedge tornado traversed along a 3.78 mi (6.08 km) path through extreme southeastern Buena Vista County, shrinking down to 1,320 yards (0.75 mi; 1.21 km) and causing EF2 damage to several farms and powerlines. Livestock shelters and farm equipment in this section of the path were destroyed as well southeast of Newell. The parent tornado then crossed Buena Vista County over into neighboring Pocahontas County afterwards.[68] In Pocahontas County, the large tornado grew to its maximum width of 2,640 yards (1.50 mi; 2.41 km). It continued northeast before erratically turning to the north, causing EF0 damage to a house northwest of Fonda. The tornado continued to the north and moved into the Sunken Island Lake and Grove Wild Life Management Area. Afterwards, the tornado impacted the community of Varina at EF2 intensity, causing heavy damage to homes and an elementary school gymnasium.[68] Despite the considerable damage, no deaths or injuries were reported as the storm passed through. The tornado then abruptly turned to the northeast, damaging a farmstead at EF1 intensity. Up ahead, extensive EF2 damage was inflicted to some structures and EF1 damage to a home, as the tornado was far west of Pocahontas.[30][68][25]

Four satellite tornadoes touched down nearby to the west-southwest of Pocahontas, with the first of them being a relatively brief, but violent EF4 tornado that formed on the west flank of the main wedge tornado at at 9:54 p.m. CDT (02:54 UTC). Despite lasting for 7 minutes along a 3.2 mi (5.1 km) path, this destructive satellite tornado completely leveled a farmhouse while a family was sheltering in a storm cellar.[71][72] Barns and a machine shed were destroyed, as a combine harvester from the shed was tossed into a field 100 yards (91 m) away, before it was severely mangled. With estimated winds of 170 mph (270 km/h), was this the strongest tornado of the event.[38] The other satellites were an EF2 tornado with winds of 115 mph (185 km/h), and a pair of EF1 tornadoes, one cyclonic and the other anticyclonic. The EF2 tornado touched down at 9:56 p.m. CDT (02:56 UTC) lasted for 2 minutes and traveled for 0.9 mi (1.4 km), before being absorbed by the previous EF4 tornado.[39][40][41] The main tornado then intensified further and reached its peak intensity, causing EF3 damage to one farmhouse and demolishing several outbuildings on the farm. More homes to the north were impacted at EF2 intensity, including one in Ware. Right after causing considerable damage in the community of Ware, the main EF3 tornado would start weakening and dissipate southwest of Havelock at approximately 10:07 p.m. CDT (03:07 UTC).[30][68][25][73]

The EF3 tornado that struck Varina and Ware alongside rural areas across Sac, Buena Vista and Pocahontas counties was the largest, longest lived and costliest tornado of the event as it caused $13 million USD in damages.[30][73] The EF4 tornado in rural western Pocahontas County, was the strongest tornado of the night and of the entire outbreak from April 9–11. This violent satellite tornado caused $2.5 million USD in damage, tracked for 3.2 miles (5.1 km) and was 587 yards (0.33 mi; 0.54 km) wide.[38] It was the first EF4 tornado to strike Iowa, since one impacted near Sibley on June 25, 2010.[74] Two other pairs of satellite tornadoes, one group of two separate EF2 tornadoes, and a duo of cyclonic and anticyclonic EF1 twin tornadoes, also occurred and caused significant damage throughout the tri-county area.[33][40][39][41] Despite the excessive tornadic activity, no fatalities or injuries were reported by this unique tornado event.[73][25]

Non-tornadic events

Hail and wind event

Accompanying the tornadoes, large hail and high winds also impacted parts of the Midwest. Initially, these events associated with the outbreak were confined to Iowa and parts of Nebraska and Minnesota on April 9. In Iowa, hail was measured up to 3.5 in (8.9 cm) in diameter, resulting in some damage to homes and cars.[4] On April 10, a large line of severe storms produced damage from northern Minnesota southward to the Texas-Mexico border. Most damage along this line resulted from straight-line winds; however, Wisconsin, 2 to 2.5 in (5.1 to 6.4 cm) diameter hail in La Crosse broke windows, dented cars and damaged homes.[75] Roughly 3,200 insurance claims worth $12 million were later made in the city.[76] Elsewhere in the state, winds up to 65 mph (105 km/h) downed numerous trees and power lines and in some instances tore roofs of buildings.[77]

In Texas, winds as high as 95 mph (153 km/h) caused extensive damage to homes and businesses, resulting in roughly $100 million in damage.[78][79] Numerous trees were felled across the region and a few structures were destroyed. In Dallas County, a few carports collapsed. Near Venus, 82 mph (132 km/h) winds damaged five homes.[77]

Derecho event

On April 11, a strong derecho brought widespread damage to much of northern Alabama as well as parts of Mississippi, Georgia and Tennessee. Near Brent, Alabama, a wind gust of 110 mph (180 km/h) was recorded 70 ft (21 m) up on a radio tower.[77]

Aftermath

Within days of the tornadoes in Iowa, excavators were brought in to clear debris and tear down homes that were damaged beyond repair.[80] On May 5, nearly a month after the outbreak, President Barack Obama signed a federal disaster declaration for Buena Vista, Cherokee, Ida, Monona, Pocahontas and Sac Counties in Iowa. This allowed for government aid to be sent to the region and aid in recovery efforts.[81] The declaration remained in effect until May 1, 2012.[82] A disaster outreach center was opened on May 6 at the Mapleton City Hall and the American Legion Post in Varina and would remain open through May 26. At these places, residents would be allowed to apply for small business and homeowner loans up to $2 million and $200,000 respectively.[83]

In September 2019, Varina reopened their post office at a new location in the community eight years after the damaging EF3 tornado that tracked through Sac, Buena Vista and Pocahontas counties. Prior to its return, the community's postal office was temporarily relocated to Fonda for the time being.[84]

See also

Notes

  1. ^ a b c 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 CDT for consistency.
  2. ^ a b c All damage totals are in 2011 USD unless otherwise stated.

References

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