November 17

With the overall upper-level system expected to track eastward across the United States High Plains on November 17, the SPC issued a slight risk for severe thunderstorm activity for an area surrounding the confluence of the Mississippi and Missouri rivers, valid for the early morning hours of the day on November 17. Model data indicated the weakening of the capping inversion coinciding with increasing instability and wind shear, which would lead to the enhanced potential for storms and tornadoes as the night progressed and the low-level jet strengthened.^[18] This overnight severe weather largely failed to develop, leading to only a very few isolated reports. However, at 0600 UTC on November 17, the SPC upgraded to a high risk for severe weather on the 17th (the second latest date in the year a high risk has been issued since 2000, and the latest in the Midwest) for regions of Illinois, Indiana, southwestern Michigan, and western Ohio, in anticipation of conditions becoming increasingly favorable for a significant tornado outbreak;^[19] this area of high risk was expanded at 1300 UTC to encompass a roughly circular region of the United States Midwest containing nearly 19 million people.^[20] Those same regions were listed as having at least a 30% chance of tornadoes, coupled with a 45% chance for wind. The issuance of a high-risk zone reflected the anticipation of an intense upper-level trough and a strong mid-level jet stream producing highly conducive conditions for the development and prolonging of severe weather.^[19]

The first signs of convection associated with the broad weather system began to form around dawn on November 17 over portions of Illinois, Iowa, and Missouri, triggered by a propagating cold front.^[21] At 1440 UTC, the SPC issued a PDS tornado watch concentrated mostly around Illinois, citing the nearly certain likelihood for severe weather over the region.^[22] Throughout the morning, discrete supercell thunderstorms developed ahead of the cold front across the length of Illinois;^[23] their expected persistence eastward prompted the SPC to issue a second PDS tornado watch at 1621 UTC, this time for areas of Indiana, Michigan, and Ohio.^[24] One of these storms would maintain a mesocyclone over a 50 mi (80 km) path.^[25] The first tornado during the outbreak touched down 1652 UTC and tracked across Peoria and Tazewell counties in Illinois; the twister was later rated EF2.^[26] This was followed shortly after by a long-tracked EF4 tornado, the strongest and costliest of the day, which tracked through multiple Illinois counties.^[27]

By around 1730 UTC on November 17, the system associated with the tornado outbreak had become centered near Milwaukee, Wisconsin. As intense storm cells propagated across Illinois and Indiana, strong low-level wind shear in the vicinity of a warm front coupled with the weather system made areas as far north as Northern Michigan a viable environment for tornado development.^[28][29] Numerous tornadoes touched down as a result of the supercells, several of which were strong to violent. In addition to spreading northward and eastward,^[30] severe thunderstorms later spread southward into the Cairo, Illinois area and later Kentucky as a result of falling barometric pressures paving the way for the spread of moisture over the area. Additional significant tornadoes occurred in that area as well.^[31][32] At around the same time, preexisting storms over Indiana and Illinois had begun to consolidate into a somewhat disorganized albeit extensive squall line.^[30] As a result of the merging, the threat of tornadoes generally decreased slowly as the storms moved from Indiana into Ohio while the development of a major wind event seemed more apparent, particularly in Ohio. Despite the change in storm mode, additional strong tornadoes still occurred as far east as Western Ohio due to circulations embedded in the squall line.^[33] This trend in severe weather also took place in other areas as clusters of isolated supercells began to coalesce into singular lines of storms.^[34]

By the 0100 UTC update of the convective outlook on November 18, storms had cleared the high risk area from the previous outlooks. However, a moderate risk for severe weather was maintained across parts of central/eastern Ohio, western Pennsylvania, and western New York ahead of the rapidly moving convective system. In addition to a 45% probability of wind, up to a 10% probability of tornadoes was maintained, with the highest threat in central/eastern Ohio, although owing to extremely marginal surfaced based instability, only one or two further isolated tornadoes were reported in this area beyond 0100 UTC. By the late evening, most of the discrete storms that existed earlier in the day had merged into squall lines and bow echoes, with any remaining mesocyclones embedded within these bands rather than individual storms.^[35] Forced along the extent of a cold front,^[36] the primary squall line raced eastward across Ohio at approximately 60 mph (97 km/h), reaching Pennsylvania by 0200 UTC.^[37] As a result of decreased atmospheric instability, the threat for tornadoes and hail had greatly diminished by this time, while the probability for damaging winds remained elevated to high; as a result, watches issued east of Ohio were severe thunderstorm watches rather than tornado watches.^[38] The final tornado associated with the outbreak was an EF0 that dissipated at 0340 UTC in Lincoln County, Tennessee (south of the area impacted by the main outbreak of tornadoes); based on Central Standard Time, this would have still occurred on November 17.^[39] By around 0800 UTC, the line of storms was quickly approaching the United States East Coast before entering the Atlantic Ocean.^[40]

Washington, Illinois

Tracking 46.36 mi (74.61 km) across four counties in Illinois,^[151] the EF4 tornado that caused major damage in Washington, Illinois was the strongest tornado documented in the state for the month of November since reliable records began in 1950.^[152] Up until that point, two other tornadoes in 1988 and 1991 were the strongest for that month.^[153] The first tornado warning on the storm cell that produced the tornado was issued at 16:50 UTC for portions of Peoria, Tazewell, and Woodford counties,^[154] nine minutes before the tornado was estimated to have touched down.^[27] By the time the tornado had developed, the tornado warning was still in effect for those areas, and at 17:06 UTC, the Particularly Dangerous Situation wording was included into the tornado warning text.^[154] Several tornado warnings were issued as the tornado tracked towards the northeast, with the final warning expiring at 1818 UTC, well after the tornado dissipated.^[155]

The tornado initially touched down at 16:59 UTC roughly 2.4 mi (3.9 km) southeast of East Peoria in Tazewell County before moving directly into town. Damage was considerable in East Peoria, where the tornado accrued $110 million in damage costs. Thousands of trees and power poles were destroyed, along with 20 houses. Major damage was sustained by 75 houses, seven businesses, and five apartment buildings, while 137 other houses and three other businesses sustained minor damage. Over 400 vehicles were damaged in East Peoria. The tornado then strengthened and broadened to its peak intensity as a high-end EF4 with winds estimated at 190 mph (310 km/h) and a damage width extending 0.5 mi (0.80 km) in diameter as it moved into the nearby town of Washington.^[42] A debris ball was detected on weather radar in association with the tornado as it moved over the city.^[156] Entire neighborhoods in Washington were leveled, and some homes were swept clean from their foundations. The Georgetown Common Apartments were severely damaged, and a pickup truck in the parking lot was found wrapped around a tree. Trees in Washington were denuded and partially debarked, vehicles were thrown, and an auto parts store was completely leveled.^[157] A total of 633 homes, seven more businesses and apartment buildings, and 2,500 vehicles were destroyed in Washington, while minor to significant damage was sustained by numerous other structures. Though 5,000 people were in the path of the tornado, only one person was killed during the storm's initial passage, while two others died of injuries sustained during the tornado in the days following November 17. The low fatality count was attributed to people successfully seeking shelter. Damage costs in Washington amounted to $800 million. Alongside the three fatalities were 121 injuries throughout Tazewell County.^[27]

The tornado then moved into Woodford County, where it maintained its size but slightly weakened to EF3 intensity as it passed near the towns of Roanoke, Benson, and Minonk. The tornado passed very close to the Parsons manufacturing plant that was destroyed in the 2004 Roanoke tornado.^[157] Despite tracking mostly across open fields, 70 farm buildings and seven homes were destroyed, with major damage sustained to 17 more. One unanchored farmhouse near Benson was swept away at EF3 intensity, and a car parked in the driveway was thrown into the basement.^[157] Roughly 100 vehicles were damaged, including several semis at a truck stop located north of Minonk, where three people were injured. Hundreds of power lines and trees were snapped, and a cell tower collapsed. Damage in Woodford County totaled $25 million.^[42] The EF3 tornado weakened further to EF2 status as it briefly tracked over LaSalle County, where damage totaled $150,000. Numerous power poles were snapped in this area, and two homes sustained significant damage. Various small outbuildings and a machine shed were also destroyed. Similar damage occurred in Livingston County, where in addition to outbuilding and power pole damage, an extensive swath of trees was sheared off, and a fire engine that was being stored in a garage was blown over as the structure was destroyed. The tornado finally dissipated 2 mi (3.2 km) east-northeast of Long Point at 17:47 UTC, after remaining on the ground for 48 minutes.^[43] In total, the tornado caused three fatalities and 125 injuries in two counties and $935 million in damage across four counties. This made it the 10th costliest tornado in United States history.^{[citation needed]} This was the first violent tornado in Illinois in November, but Illinois has seen violent tornadoes in December.^[158]

New Minden, Illinois

At around noon on November 17, an EF4 tornado tracked across portions of Washington County, Illinois and resulted in the deaths of two people, becoming the second tornado that day to cause fatalities. The St. Louis, Missouri Weather Forecast Office first issued a tornado warning for areas of Clinton County and northern Washington County, Illinois at 1753 UTC, due to the tornadic threat of a rapidly moving severe thunderstorm in the region.^[159] A tornado was estimated to have touched down 4.4 mi (7.1 km) southwest of New Minden near I-64 at 18:04 UTC, 11 minutes after the issuance of the initial tornado warning. A semi-trailer truck was blown off of the highway near this point, injuring the driver.^[160] Just past the interstate, a farm home sustained EF1 damage and a man sustained minor cuts at that location. A nearby hay barn was destroyed at EF2 intensity.^[161][162] The tornado rapidly intensified as it tracked northeastward, striking a small farm at mid-range EF4 intensity with maximum winds estimated to have been 180 mph (290 km/h).^[163] The homestead there was completely swept away with little debris left behind, and other buildings on the farm grounds sustained various degrees of damage. Several vehicles on the property were rolled as well. An elderly couple were killed in the house as it was swept from its foundation.^{[160][161][162]}

By 18:07 UTC, the tornado continued through rural areas towards New Minden at EF2 strength, snapping power poles, destroying outbuildings, and removing much of the roof from a site-built home and a garage. A truck was overturned as well.^[162] The tornado then struck the north side of New Minden directly,^[162][163] inflicting significant damage to a church and several homes, two of which sustained EF3 damage with total roof loss and collapse of exterior walls. East of New Minden, a farm sustained EF2 damage, where outbuildings were completely destroyed and the farmhouse was shifted from its foundation. Trees were snapped and a grain bin was destroyed in this area as well. Moderate damage continued as the tornado crossed through rural areas northwest of Hoyleton. A mobile home 2 mi (3.2 km) north of Hoyleton was completely destroyed at EF2 intensity and a nearby outbuilding was damaged before the tornado dissipated at 18:13 UTC, 2.6 mi (4.2 km) north-northeast of Hoyleton.^[160] In total, the twister, which peaked at EF4 intensity, lasted for nine minutes and tracked across 10.59 mi (17.04 km).^[49] Though initial damage surveys suggested a much longer damage path associated with one tornado, the damage was later reassessed to indicate the existence of two separate albeit consecutive tornadoes,^[163] with the EF4 tornado followed by an EF1 tornado that lasted for five minutes and had a path 4.76 mi (7.66 km) long.^[161][50] The tornado warning for Washington and Clinton counties expired at 1830 UTC, after both tornadoes dissipated.^[163]

Paducah, Kentucky/Brookport–Shady Grove–Unionville, Illinois

The final killer tornado of the outbreak was a long-tracked, heavily rain-wrapped EF3 that moved along the Ohio River through parts of Kentucky and Illinois and devastated the small town of Brookport, along with nearby rural communities.^[164][106]

The tornado initially touched down just inside western McCracken County, Kentucky northeast of Kevil and moved across the northern fringes of Paducah. The tornado was at EF2 strength in McCracken County, demolishing an abandoned mobile home, causing roof and siding damage to many structures (most of them being homes), destroying the foyer of a church, bending road signs, ripping a wooden fence out of the ground, and blowing over chain-link fences. At one building, three metal roll-up doors were blown in and part of a wall was blown out. The tops of three steel power transmission towers were bent over, power lines were downed, train car covers were blown off, and a sports utility vehicle was blown 30 yards (27 m) into a ditch as well. Some damage to buildings and cooling towers at the Paducah Gaseous Diffusion Plant was noted, though no hazardous materials were released. The tornado crossed the Ohio River into Massac County, Illinois where it went through Brookport at low-end EF3 strength and completely destroyed dozens of mobile homes, many of which were blown over 100 feet (30 m). Also in Brookport, a frail site-built home was leveled, and dozens of homes, garages, storage buildings, and businesses sustained structural damage. Hundreds of trees were downed and cars were tossed as well. The tornado caused some minor damage to guard rails on the Ohio River bridge that carries traffic from Paducah to Brookport on U.S. Highway 45. East of Brookport, the tornado maintained EF3 strength as it impacted the small rural community of Shady Grove. Mobile homes in Shady Grove were obliterated, with their frames wrapped around trees. An empty school bus was picked up and thrown, and a two-story home was pushed off of its foundation and had many of its first floor walls ripped off, along with its porch. Past Shady Grove, the tornado struck the neighboring community of Unionville, where additional low-end EF3 damage occurred. Many trees in Unionville were snapped, and a large double-wide mobile home was obliterated and swept away, with debris scattered 500 feet. The home's heavy 7-by-12-foot concrete porch slab was lifted and moved by the tornado. The tornado weakened to EF2 strength as it moved briefly through Pope County and then back across the Ohio River into Livingston County, Kentucky, destroying several mobile homes and barns in this area and snapping numerous trees. In Lyon County the tornado downed additional trees before dissipating. Three people were killed and 33 additional people were injured along the tornado's 42 mi (68 km) long path. All fatalities occurred in mobile homes that were destroyed in Brookport. Snow that fell in the area during the days following the tornado hindered cleanup efforts.^{[136][164][161][106]}