Tornado outbreak in the United States
From April 14–16, 2011, a tornado outbreak, among the largest recorded tornado outbreaks in U.S. history, produced 178 confirmed tornadoes across 16 states, resulting in severe destruction on all three days of the outbreak. A total of 38 people were killed from tornadoes and an additional five people were killed as a result of straight-line winds associated with the storm system. The outbreak of severe weather and tornadoes led to 43 deaths in the Southern United States. This was the largest number of fatalities in an outbreak in the United States since the 2008 Super Tuesday tornado outbreak. It is locally referred to as the "Forgotten Outbreak" in Alabama as it was vastly overshadowed by the 2011 Super Outbreak less than two weeks later.
Meteorological synopsis.
April 14.
On April 14, a strong storm system in the southern section of the Rocky Mountains moved east to the central and southern Great Plains region during the afternoon and to the mid and lower Mississippi River Valley during the overnight hours. The system was accompanied by strong winds in the middle and high levels of the atmosphere along with cold upper air temperatures. With these elements coming together with moisture moving north from the Gulf of Mexico, it resulted in conditions favorable for severe weather. A moderate risk of severe weather was issued for that day by the Storm Prediction Center as a result across eastern Oklahoma and neighboring parts of Arkansas, Kansas, Missouri and Texas. With a dryline extending from southern Kansas to Texas, thunderstorms began developing along the dryline across north and south central areas of Oklahoma by 3:10 pm CDT (2010 UTC). These storms would form into supercells and move into eastern Oklahoma by 4:00 pm CDT (2100 UTC).
Storm chasers in the region reported multiple funnel clouds and two touchdowns, neither of which resulted in damage. Several tornadoes were confirmed through storm chaser video and local emergency management services. A large, intense tornado later caused severe damage in and around the towns of Atoka and Tushka. Many houses were destroyed or flattened from what was at times a double tornado with two well-defined vortices. Numerous injuries were reported in the latter of these areas. Two died and 43 more were injured in Tushka. In Arkansas, strong winds produced by thunderstorms killed at least seven people. Of those deaths, five were confirmed to have been from straight-line winds and two were as a result of a weak tornado embedded in an overnight squall line that tracked across the state.
April 15.
A moderate risk of severe weather also existed for April 15 across much of Alabama and Mississippi. During the pre-dawn hours into the morning of April 15, tornadic activity temporarily waned with only isolated activity. However, by late that morning, supercell thunderstorms developed again over parts of Mississippi, and tornadoes began to touch down again. A tornado emergency was declared for the northern Jackson metropolitan area shortly after 11:00 am CDT (1600 UTC), as a result of a widely photographed tornado that moved through parts of the city and the adjoining city of Clinton. The destructive tornado moved across the area producing severe damage and numerous injuries according to WLBT coverage. That afternoon, Mississippi State University spotters confirmed another large tornado in east-central Mississippi and west-central Alabama and the second tornado emergency of the outbreak was issued. ABC 33/40 coverage reported that the tornado was 3/4 mile (1.2 km) in width.
Two additional tornado emergencies were also issued that afternoon for other storms in Attala County, Mississippi, and Choctaw County, Alabama, and a fifth such issuance occurred near Leakesville, Mississippi, that evening, where a large EF3 wedge tornado produced severe damage and 4 fatalities. Local storm reports report at least 7 fatalities from the storms on April 15.
April 16.
The next day, a moderate risk of severe weather was issued for April 16 for the Carolinas and southern Virginia as the cold front tracked eastward and a mesolow developed across the Appalachians. As storms began moving into areas of strong atmospheric instability, a PDS Tornado Watch was issued shortly after noon and a high risk, the first of 2011, was issued shortly thereafter at 12:30 pm EDT (1630 UTC) for central and eastern North Carolina and immediate adjacent areas in South Carolina and Virginia. A squall line descended the Blue Ridge, and rapidly intensified along the Interstate 77 corridor.
As this line tracked eastward, wind damage was reported in Salisbury and Lexington, where tree and roof damage was widespread. The Salisbury storm - an EF1 - became the first confirmed tornado from the outbreak in North Carolina, followed shortly thereafter by tornadoes near Monroe (EF0) and north of Burlington (EF1). The Burlington area storm would mature into the first of multiple long-tracked, multi-tornado tornadic supercells, producing additional tornadoes near Roxboro and South Hill, Virginia.
Moving rapidly to the east, the squall line entered areas that had experienced sunnier weather earlier in the day, and the squall line began to rapidly fragment into powerful discrete supercells by early afternoon. Explosive wind shear also made the atmosphere extremely prime for tornadic development. At about 3:15 pm EDT (1915 UTC), a tornado emergency - the sixth of the outbreak - was issued for an especially intense tornado in the Raleigh-Durham metropolitan area. This cell had developed in Moore County, and had at one point been a very strong tornado - a high-end EF3 twister - in the city of Sanford. A very prominent hook echo was easily visible on local radar returns, with a hail core and debris aloft also reflected in radar imagery.
This storm, which may have been a mile wide, tracked through the southeast edge of downtown Raleigh, on a southwest-to-northeast trajectory that passed through miles of suburbs surrounding the city. While damage in Wake County fluctuated between EF0 and EF2, it was accompanied by debris fallout from the Sanford area, when the storm was far more violent. Tracking through Raleigh, the tornado crossed three interstate highways, and narrowly missed a nuclear power plant as it moved from southwest to northeast through the densely populated (900,000+ population) county. The campus of Shaw University in downtown Raleigh was so severely damaged that classes were suspended for the remainder of the semester.
Soon afterwards, two additional tornado emergencies were issued farther south and east, as radar images of the developing supercells indicated very prominent hook echoes. Of the larger cities in eastern North Carolina, Fayetteville, Jacksonville, and Wilson all endured direct hits from EF2 or EF3 tornadoes. A tornado or tornado family that began in the city of Fayetteville, briefly closed interstate 95 in Johnston County, due to debris blocking the highway.
Late in the outbreak and farther into northeastern North Carolina, another EF3 tornado in Askewville, North Carolina, in rural Bertie County caused 12 fatalities and extensive damage in the towns of Askewville and Colerain, just west of the Chowan River. Additional destructive tornadoes - produced by the same line of supercells - caused damage northwest of the Charleston metropolitan area, and at several locations in the northeastern part of South Carolina, including Dillon County and multiple locations in Georgetown County.
Tornadoes also struck several locations in Virginia, including a destructive tornado in Gloucester County and a brief tornado 300 miles to the west in Rockbridge County. A tornado touched down in the switchyard of the Surry Nuclear Power Plant in southeastern Virginia, cutting off external power to the plant and leading its two reactors to trip. Because of this, a NRC Unusual Event, the lowest level of emergency, was declared. Diesel backup power was restored after a brief outage and the shutdown and cooling of the plant proceeded as designed with no physical damage to the reactors or release of radiation. A fuel oil leak occurred at an above-ground storage tank near the station's garage. The supercells finally emerged into the Atlantic Ocean late that evening, ending the tornado outbreak after over 52 hours.
Confirmed tornadoes.
De Kalb, Mississippi–Geiger, Alabama.
This strong long-tracked EF3 wedge tornado first touched down southeast of Philadelphia, Mississippi, in Neshoba County at 12:53 p.m. CDT (17:53 UTC). In the area of County Road 450, the tornado downed numerous trees, including many pine, before it pushed a mobile home over and damaged the roof of a house. Crossing MS 491, the tornado began to intensify, destroying a large portion of two chicken houses and causing extensive tree damage. It weakened slightly as it crossed County Road 729 and then moved into Kemper County soon after. A home sustained minor to moderate damage along County Road 729 just inside Neshoba County. The tornado intensified again, to EF3 intensity, as it approached Little Rock Road and MS 495. At this location, there was extensive structural damage to two frame homes, two mobile homes were completely destroyed (with debris being carried some distance away), several power poles were snapped, and some trees were debarked and denuded.
The tornado weakened a little but continued to cause extensive tree damage and downed power lines and poles as it moved east-northeast toward De Kalb, Mississippi. As the tornado crossed MS 16 west of De Kalb, it destroyed several mobile homes, heavily damaged the second story of a frame home, and caused roof damage to other frame homes. Extensive tree and power line damage also occurred in this area. Passing just north of the town of De Kalb, it again produced EF3-strength damage, completely destroying a double-wide mobile home (wrapping the frame around trees several hundred yards away and carrying remnants across a road a considerable distance away), causing intense tree damage, including denuded trees, and snapping power poles. Another mobile home was destroyed and nearby site-built homes sustained roof damage.
As the tornado crossed MS 39, it continued causing extensive tree damage, with large swaths of land where nearly every tree was snapped, many of which were debarked. In addition, a site-built home suffered heavy roof and structural damage, another home sustained heavy roof damage, and several outbuildings were destroyed. Here, the tornado reached its maximum width at , before weakening and narrowing a little and crossing Mississippi Highway 16 again, just west of Scooba. Numerous trees and a couple of power poles were snapped in this area. The tornado then crossed US 45 to the south of Scooba with a relatively narrow but intense damage swath that was rated high-end EF2 to low-end EF3. A large warehouse building was completely destroyed, three homes sustained roof damage, and a pickup truck was thrown a considerable distance. More intense tree damage occurred in this area with debarking and denuding. The tornado widened again east of Scooba, causing heavy damage along Mississippi Highway 16 near Giles Road. Several homes sustained heavy roof damage, power poles were snapped, and more trees were denuded. About 3200 acres of pine and hardwood forest were damaged in Kemper County.
The storm crossed into Sumter County, Alabama, as a wedge tornado at EF3 strength. The tornado immediately struck Geiger, causing extensive damage to numerous homes and businesses. According to ABC 33/40 coverage, numerous houses and many mobile homes were reported to be destroyed or flattened. East of town, thousands of trees were either snapped or uprooted before the tornado lifted at the Tombigbee River just prior to crossing into Greene County at 2:05 p.m. CDT (19:05 UTC). The tornado traversed across three counties, reaching maximum estimated winds of . Five people were injured, all in Kemper County, Mississippi.
Sanford–Raleigh, North Carolina.
At 2:53 p.m. EDT (18:53 UTC) on April 16, a moderately large and very intense tornado developed around Sanford, North Carolina, in Lee County. A Lowe's Home Improvement Warehouse store in Sanford was destroyed, however, there were no fatalities or serious injuries there as staff spotted the approaching storm, and rushed staff and customers to safety in time. Several retailers adjacent to Lowe's were also heavily damaged. In a nearby residential area, two people were killed, and 30 homes were destroyed. Some homes were reduced to rubble by the tornado. Aerial footage broadcast on WRAL showed a very wide debris path through the area. The most severe damage was in this area, rated as a high-end EF3, where three other warehouses were destroyed and two apartment buildings lost their upper levels. Mobile homes in the area were destroyed and vehicles were thrown by the tornado.
Generally maintaining its size and strength, the storm then paralleled U.S. Route 1. It weakened southeast of the community of