On the afternoon of April 27, 2011, a large, long-tracked, and destructive EF4 tornado, known informally as the Section–Flat Rock EF4 by the National Weather Service, moved across portions of North Alabama and North Georgia, tracking near the towns of Section, Pisgah, Flat Rock, Higdon and Rosalie in Alabama and Trenton in Georgia along its track. The tornado directly killed 15 people, injured at least 50 more, and impacted hundreds of structures. It occurred as part of the largest tornado outbreak in modern history, and was one of multiple EF4-rated tornadoes to be confirmed that day.
The tornado first touched down near Section, initially producing EF0 and EF1-rated damage to trees and homes before becoming violent north of Pisgah. Several homes were heavily damaged in the area and trees were blown down; the tornado killed 13 people in Jackson County alone. The tornado maintained its intensity as it moved through Dekalb County before crossing into Dade County, Georgia at EF4 intensity, where two people would be killed and heavy damage was inflicted to the community of Trenton. The tornado lifted after 56 minutes on the ground. Damage from the tornado was rated EF4 on the Enhanced Fujita scale, and damage surveyors estimated that the tornado had maximum estimated wind speeds of approximately . WDEF-TV described the tornado as the "longest-running in our area".
Meteorological synopsis
Setup The environmental conditions leading up to the 2011 Super Outbreak were among the "most conducive to violent tornadoes ever documented". On April 25, a vigorous upper-level shortwave trough moved into the Southern Plains states. Ample instability, low-level moisture, and wind shear all fueled a significant tornado outbreak from Texas to Tennessee; at least 64 tornadoes touched down on this day. An area of low pressure consolidated over Texas on April 26 and traveled east while the aforementioned shortwave trough traversed the Mississippi and Ohio River valleys. Another 50 tornadoes touched down on this day. The multi-day outbreak culminated on April 27 with the most violent day of tornadic activity since the 1974 Super Outbreak. Multiple episodes of tornadic activity ensued with two waves of mesoscale convective systems in the morning hours followed by a widespread outbreak of supercells from Mississippi to North Carolina during the afternoon into the evening.
Tornadic activity on April 27 was precipitated by a 995 mbar (hPa; 29.39 inHg) surface low situated over Kentucky and a deep, negatively tilted (aligned northwest to southeast) trough over Arkansas and Louisiana. A strong southwesterly surface jet intersected these systems at a 60° angle, an ageostrophic flow that led to storm-relative helicity values in excess of 500 m2s−2—indicative of extreme wind shear and a very high potential for rotating updrafts within supercells. Ample moisture from the Gulf of Mexico was brought north across the Deep South, leading to daytime high temperatures of and dewpoints of . Furthermore, convective available potential energy (CAPE) values reached 2,500–3,000 J/kg−1.
Forecast
On the morning of April 27, a strong cold front with several areas of embedded low pressure extended from the Texas Hill Country northeastward towards the Arklatex and the Ozarks, and later into the lower Ohio Valley. Warm moist air was in place due to strong southerly flow ahead of the front over Mississippi, Alabama, and Tennessee. An upper level disturbance sparked a broad area of showers and thunderstorms as it moved across the frontal boundary on the previous evening. The eastern edge of the line of showers and storms continued to move eastward, in concert with the upper disturbance, reaching the northwest Alabama border around 2:00 a.m. CDT.
This produced the last and most violent round of severe weather, which began around 2:30 p.m. CDT for northern Alabama as supercells began to line up to the southwest of the area. During the early afternoon hours, the potential for destructive tornadoes was highlighted by the Storm Prediction Center's upgrade to a high risk for severe weather around 1:00 p.m. CDT. This prompted a particularly dangerous situation (PDS) tornado watch, which was issued for northern Alabama and portions of southern Tennessee at 1:45 p.m. CDT. The bulletin that accompanied the watch read:
The potential for tornadoes ramped up from noon through 9:00 p.m. CDT. During this period, much of Alabama experienced numerous supercell thunderstorms that produced numerous tornadoes, including the Trenton tornado.
Morning EF1 tornado in Trenton and New England, Georgia On the morning of April 27, an EF1 tornado touched down a short distance to the north of where the EF4 tornado would later impact. The tornado touched down at around 8:40 a.m. CDT on top of an interchange in the western portions, moving to the northeast. West of Wolverine Drive the tornado reached EF1 intensity, impacting the Dade Elementary before crossing 1st Street and John Street. It weakened to EF0 strength shortly before passing over Wren Avenue. The tornado moved through a neighborhood between North Main Street and Interstate 59 before moving directly parallel to Highway 11. It reached EF1 intensity for a second time as it impacted the northwest portions of New England, before weakening again as it crossed Squirrel Town Creek. The tornado continued northeast through unpopulated areas in Dade County to the west of Morganville. It remained relatively thin as it moved over the Slygo Ridge, part of the Slygo Valley region. Several roads were hit at EF0 intensity as the tornado continued, eventually crossing Interstate 24 and lifting a short distance to the west of Hooker. The tornado caused no fatalities or injuries.
Tornado summary
This multiple-vortex EF4 tornado that originated from the Cullman supercell, with maximum sustained winds of up to , devastated portions of Jackson and DeKalb counties in Alabama, as well as Dade and Walker counties in Georgia along a path at times up to wide, killing 14 people and injuring at least 50 others.
The tornado first touched down on Alabama State Highway 35, moving to the northeast. It moved parallel to County Road 390, before crossing over Alabama State Highway 40. Trees were blown down north of County Road 224, before the tornado briefly moved over an offshoot of the Tennessee River. It continued moving northeast through hilly areas of Marshall County, continuing to produce tree damage and damaging several homes near County Road 88. Off Alabama State Highway 88, several homes sustained damage and trees were blown down on the properties. The tornado then crossed County Road 432 and County Road 57, impacting the Dogwood Branch of the Tennessee River directly north of Pisgah. On County Roads 369, several homes were heavily damaged.
To their north the tornado tossed debris into a grove of trees and scattered debris from a property across a field. The tornado then passed over County Road 58 and County Road 357, where more damage was done to trees and homes. A home was destroyed as the tornado passed over County Road 58 before the tornado crossed over the Rocky Branch of the Tennessee River. It then impacted County Road 426 and County Road 126 north of the communities of Glenzaida and Rosalie. The tornado continued moving through areas a short distance south of the Coon Gulf and northwest to north of County Road 78. The tornado rapidly intensified to low-end EF4 strength in this area as it destroyed numerous mobile homes and brick-foundation homes, scattering debris hundreds of yards and killing three people.
Thousands of trees were snapped and debarked, vehicles were thrown up to in different directions, and barns and chicken houses were heavily damaged, along with the roof of a church. As it passed near Flat Rock and Higdon, the tornado reached high-end EF4 strength, mowing down thousands of trees in this rural area. As the tornado struck a farm, a home and two chicken houses were completely obliterated and swept away. A heavy propane tank was lofted and thrown from one of the chicken houses, and 19 cattle on the property were killed. Remarkably, a family of four taking shelter inside the house were completely unharmed. Three people were killed in a home southwest of Flat Rock. The Shiloh Community Church in the Higdon area was hit by the tornado; the same church would be struck by another tornado in 2020. Three tornadoes would move over this general area in a ten-hour span, the deadliest being the Flat Rock-Trenton EF4.
The tornado maintained EF4 strength as it tore through the rural community of Shiloh, sweeping away numerous mobile homes and block foundation homes and killing five people at that location. Thousands of trees were snapped, a log cabin was destroyed, livestock was killed, chicken houses were flattened, and a van was lofted and dropped into a field away from where it originated. The tornado then crossed then crossed into Georgia, immediately producing EF4-rated damage west of Workman Drive. As it crossed the road, more EF3 damage was inflicted to a home, which was completely destroyed. It maintained EF3 intensity as it passed over Bible Camp Road; the tornado's outer circulation struck the Vaught Lake area at EF0 to EF2 intensity. On County Road 301, the tornado destroyed another home with wind speeds that were estimated to have been as high as . To the northeast the tornado crossed Back Valley Road, where several homes were heavily damaged or destroyed.
The exterior walls of one home were collapsed inward by the tornado as it impacted the Whispering Pines Drive and Tanglewood Trail area. After crossing McKaig Road and Ashton Lane, the tornado impacted Interstate 59 and South Main Street. At this point along its track, the tornado was nearing downtown Trenton. It hit a neighborhood of homes on Pine Avenue, Oak Avenue and Walnut Avenue ease of the State Route; EF2 damage was inflcited to a residence located on Oak Wood Avenue. Dozens of homes in Trenton were either completely destroyed or sustained major damage, and tens of thousands of trees were downed in the area. A grocery store, two apartment complexes, and a funeral home were destroyed as well. The Dade Elementary School was damaged by the tornado, and the tornado left a path of damage that was visible several days after the event.
The tornado weakened to EF2 strength as it struck Flintstone further to the northeast, but still resulted in major damage. Numerous trees and power lines were downed, 7 homes were destroyed, 26 sustained major damage, and 35 sustained minor damage in the Flintstone area. The tornado continued northeast, weakening to EF0 strength before finally dissipating near Fort Oglethorpe. The tornado tracked along a path, at times up to wide.
Aftermath
Damage, recovery efforts and studies
Heavy damage was produced by the tornado in the Sand Mountain region of North Alabama. The Sand Mountain Bible Camp, located near Shiloh, was heavily damaged. Walker County Emergency Management and Walker County Emergency Services cleared debris from roadways and performed search-and-rescue operations in the Flintstone area; four EMA disaster centers were opened by the agency. In Trenton, the tornado resulted in the closure of several stores and businesses. the Trenton Ingles Supermarket remained closed for four months after the tornado, The Moore Funeral Home property was heavily affected by the tornado, although it was later rebuilt. In addition to business damage, several rental properties in Trenton suffered some form of damage from the tornado.