EF4 Cordova tornado, Alabama, April 27, 2011

1. EF065 to 85 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mph

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mphthis tornado

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF4

Date

April 27, 2011

Touchdown

3:40 PM CDT (20:40 UTC)

Lifted

5:56 PM CDT (22:56 UTC)

On the ground

136 minutes

Path length

127.8 miles (205.6 km)

Path width

1,408 yards (1287 m)

Deaths

13

Injuries

54

Property damage

$170 million

Counties

Pickens, Tuscaloosa and Fayette counties

Touchdown point

33.251, -88.181

Lift-off point

34.283, -86.349

Record number

1104271440-01

99 damage points were recorded along this path by NWS BMX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF4. The highest wind the damage implies is 170 mph.

• Edge of EF1 trees, not in pic.
• hundreds of trees snapped or uprooted as well.
• Start Point of Mountain Woods Lake EF-2 Tornado.
• End point of Mountain Woods Lake EF-2 Tornado.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

A powerful storm system crossed the Southeast United States on Wednesday, April 27, 2011, resulting in a large and deadly tornado outbreak. This epic event broke the record for number of tornadoes in a day for the state of Alabama, becoming the most significant tornado outbreak in the state���s history. ||Central Alabama had two rounds of severe weather that day. During the early morning hours, a Quasi-Linear Convective System quickly moved across the northern half of the National Weather Service, Birmingham county warning area. Straight line winds of 90 mph (78kts) or greater and 11 tornadoes lead to widespread damage and power outages. During the afternoon, long-lived supercell thunderstorms produced long-track, strong and violent tornadoes. Destruction and loss of life across many towns and communities was devastating. ||The hardest hit areas included Shottsville and Hackleburg, both in Marion County, where winds of 160 mph and 210 mph respectively, caused unimagineable damage. Cordova, in Walker County, was hit twice; by a tornado along the Quasi-Linear Convective System during the early morning hours and again in the afternoon by a long-track EF4 tornado. A long track tornado moved across the city of Tuscaloosa and the western suburbs of Birmingham, resulting in the complete destruction of whole neighborhoods and numerous injuries and fatalities in those heavily populated areas. The same parent supercell produced another violent tornado in east Central Alabama as it tracked across St. Clair and Calhoun Counties, resulting in additional fatalities and incredible damage to a number of neighborhoods. Another violent EF4 tornado tracked across portions of Elmore and Tallapoosa Counties, including Lake Martin, destroying numerous homes and a large section of a mobile home park. ||Most of the violent tornadoes from this day were captured on video by a number of people, including storm spotters and chasers, as well as numerous television news crews and remotely controlled web-enabled video cameras. This allowed unprecedented coverage and viewing of this historic event in real time from people worldwide.

The second segment of this long track tornado crossed into Tuscaloosa County south of Pleasant Ridge Church Rd. This tornado began in Pickens County, 5 miles northeast of Pickensville, and tracked northeastward into Tuscaloosa County. It continued through portions of Fayette, Walker, Cullman (See Storm Data for Huntsville), and Blount Counties, before it dissipated in Marshall (See Storm Data for Huntsville) County. While the average path width of this tornado in this portion of Tuscaloosa County was around 0.5 mile (880 yds), the maximum path width maximum was 0.8 mile (1408 yds), which occurred along AL Hwy 171. The tornado strengthened as it entered west Tuscaloosa County to an EF3 rating with winds of 140 mph. It produced significant tree damage along AL Hwy 171. Trees were debarked with only bare large limbs left. Other trees at this location were snapped. The tornado moved northeast weakening to an EF0 rating, but continued to produce tree damage across northwest Tuscaloosa County. The tornado moved into southeast Fayette county 0.5 mile east of Fayette Rd.

The fifth segment of this long track tornado entered Fayette County for the second time at CR 83, south of Boley Springs, and moved northeast where it exited Fayette County south of Blue Water Trace Rd . This tornado began in Pickens County, 5 miles northeast of Pickensville, and tracked through Tuscaloosa, Fayette, Walker, Cullman (See Storm Data for Huntsville), and Blount Counties, before it dissipated in Marshall (See Storm Data for Huntsville) County. While the average path width of this tornado in this portion of Fayette County was around 0.5 mile (880 yds), the tornado maximum path width was 0.75 mile (1320 yds) as it entered the county. The tornado strengthened to an EF3 rating, with winds of 140 mph, as it crossed CR 83 in Fayette County, where a mobile home was completely destroyed, with the remaining debris thrown a considerable distance, which resulted in 2 fatalities. The tornado continued northeast, where it crossed Wilcutt Road and CR 46, where several additional mobile homes were completely destroyed and the debris thrown a considerable distance. This resulted in two additional fatalities. Along this path, two homes sustained complete roof loss or partial roof loss, respectively. In addition, several cars were thrown and destroyed, and a building sustained extensive damage to the exterior brick veneer. The tornado caused considerable damage to trees, completely debarked trees with only stubs of largest branches as it continued northeast toward the Walker County line.

The deaths

4 direct deaths are recorded for this tornado, each with what Storm Data knows of it.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

25 minutes of warning. NWS BMX issued a tornado warning for this county at 20:15 UTC, 25 minutes before the tornado touched down, in force until 21:15 UTC.

The county was under a tornado watch, issued at 18:45 UTC and running to 01:28 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a High Risk, with a 0.45 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:12 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

The Birmingham radar (KBMX), 81 km away, was scanning. The volume nearest the touchdown began at 20:37 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2011 tornado in AlabamaEvery tornado in Alabama since 1950Warnings in force in Alabama nowThe forecast where you are

209 more were confirmed in the United States that day.

All 210 of them

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.