Tornadoes · United States · Alabama · 2011

EF1 tornado, Mertz to Blocton, Alabama, April 15, 2011

From Mertz to Blocton, this EF1 tornado ran 21.8 miles across Bibb County on April 15, 2011, touching down at 4:00 PM CDT and reaching 1,760 yards wide. It killed nobody, and did $89,000 of property damage.

The rating scale

Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  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 mphthis tornado

    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 mph

    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.

The record

Rating
EF1
Date
April 15, 2011
Touchdown
4:00 PM CDT (21:00 UTC)
Lifted
4:34 PM CDT (21:34 UTC)
On the ground
34 minutes
Path length
21.8 miles (35.0 km)
Path width
1,760 yards (1609 m)
Deaths
0
Injuries
0
Property damage
$89,000
County
Bibb County
Touchdown point
32.904, -87.362
Lift-off point
33.109, -87.077
Record number
1104151500-01

The damage survey

15 damage points were recorded along this path by NWS BMX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 105 mph.

  • Several hardwood limbs snapped off and several softwood trees uprooted along cahaba river road. Damage likely extends northeast but no road access.
  • Numerous trees snapped and uprooted. One tree on a mobile home. width of damage one mile.
  • Numerous trees snapped and uprooted.
  • .numerous trees uprooted and snapped. Partial metal roof peeled of house.

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

What the Weather Service recorded

A potent storm system, which wreaked havoc across the eastern half of the United States on April 14-16, produced a significant and historic tornado outbreak across Central Alabama on April 15. Forty tornadoes, 30 of which touched down in Central Alabama, occurred in the state. At the time, this set a new record for number of tornadoes within the state from one event. This record was broken on April 27, 2011. ||A surface low developed across the Central Plains on Thursday, April 14, and strengthened as it moved into the mid-Mississippi River Valley. In response, surface dew points in the middle to upper 60s surged northward into Central Alabama and deep vertical wind shear increased, providing support for tornadic supercell development. A weakening line of thunderstorms moved into northwest Central Alabama early Friday morning. The southern end of this line intensified by mid day as it encountered a more unstable airmass. South of the line, supercells formed in Mississippi and tracked eastward into west Central Alabama. The entire system pushed east across the area over the course of about twelve hours, exiting east Central Alabama in the early morning hours on Saturday, April 16. In addition to the thirty tornadoes, the storm system produced widespread straight line wind damage and numerous large hail reports.

A tornado touched down in Bibb County, along State Highway 25. The tornado has been rated an EF-1, with maximum winds at 105 mph. As the tornado moved northeast, it crossed Highway 5 south of West Blocton where several homes sustained moderate roof damage. Along the path, hundreds of trees were either snapped or uprooted. The tornado lifted along County Road 24, 3 miles east of West Blocton.

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

The warnings

21 minutes of warning. NWS BMX issued a tornado warning for this county at 20:39 UTC, 21 minutes before the tornado touched down, in force until 21:45 UTC.

The county was under a tornado watch, issued at 16:21 UTC and running to 00:51 UTC.

Issued (UTC)ExpiredProductOffice
15:00 UTC06:00 UTCWind AdvisoryBMX
16:21 UTC00:51 UTCTornado WatchBMX
20:39 UTC21:45 UTCTornado WarningBMX
21:28 UTC21:59 UTCTornado WarningBMX
21:33 UTC22:15 UTCSevere Thunderstorm WarningBMX
21:42 UTC22:15 UTCTornado WarningBMX
22:13 UTC22:48 UTCTornado WarningBMX
00:51 UTC03:21 UTCTornado WatchBMX

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 forecast that day

The Storm Prediction Center had this point in a Moderate Risk, with a 0.15 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:56 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 air that afternoon

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.

Birmingham, AL (KBMX), 12:00Z

9.0 hours before the tornado, 45 km from the path. April 15, 2011.

Skew-T log-pSkew-T log-p diagram, Birmingham, AL at 12:00Z on 2011-04-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -86056, lifted condensation level 1553 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Birmingham, AL at 12:00Z on 2011-04-15The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 282 square meters per square second, 0 to 6 km bulk shear 46 knots.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-86056 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1553 m above ground
0-6 km bulk shear
46 kt
0-1 km bulk shear
28 kt
0-1 km storm-relative helicity
282 m²/s²
0-3 km storm-relative helicity
365 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5
0-3 km lapse rate
4.6 K/km

Open this sounding in Storm Lab

The radar

The Birmingham radar (KBMX), 46 km away, was scanning. The volume nearest the touchdown began at 21:01 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.

What was reported nearby

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

Time (UTC)ReportWhereCountyRemark
20:16 UTCTORNADO 33 Se RalphGreene, ALAN EF-3 TORNADO TOUCHED DOWN NEAR RALPH IN NORTHEAST GREENE COUNTY AND MOVED NORTHEAST TO NEAR 1.5 MILES EAST OF UNIVERSITY MALL IN TUSCALOOSA. HUNDREDS OF TREES WERE SNAPPED OR UPROOTED AND A POWER TRANSMISSION TOWER WA
20:31 UTCTORNADO 22 Nnw GreensboroHale, ALAN EF-2 TORNADO TOUCHED DOWN NEAR STATE HIGHWAY 14 AND LIFTED NEAR STATE HIGHWAY 69. THERE WERE NO KNOWN INJURIES...BUT ONE PERSON WAS TRAPPED IN AN OVERTURNED MOBILE HOME FOR SEVERAL HOURS. THERE WAS SIGNIFICANT DAMAGE
20:36 UTCTORNADOTuscaloosaTuscaloosa, ALTUSCALOOSA FIRE DEPARTMENT REPORTED TORNADO ON THE GROUND ON HWY 69 SOUTH NEAR SHELTON STATE WITH DEBRIS ON ROADWAY.
20:38 UTCTORNADOTuscaloosaTuscaloosa, ALOLD DAYCARE CENTER ON HWY 69 SOUTH RECIEVED MAJOR STRUCTUAL DAMAGE. HILLCREST CENTER RECIEVED STRUCTURAL DAMAGE TO SIGNS.
20:39 UTCTORNADOTuscaloosaTuscaloosa, ALDAMAGE AT THE TOKYO RESTAURANT ON 69 SOUTH. SEVERAL TRAILER HOMES AT A DEALERSHIP TURNED OVER AND SPEEDY OIL CHANGE NORTH OF DEALERSHIP WAS HEAVILY DAMAGED. ON 82 SEVERAL TREES DOWN AND MOTEL 6 WAS HEAVILY DAMAGED.
20:42 UTCTORNADO8 N GreensboroHale, ALROOFS OFF OF HOUSES
20:42 UTCTORNADOTuscaloosaTuscaloosa, ALSTUCTURAL DAMAGE TO SEVERAL HOMES IN THE BEACH HILL AREA.
20:45 UTCTORNADO9 N GreensboroHale, ALPUBLIC REPORTS TORNADO ON THE GROUND CROSSING HIGHWAY 25 NORTH OF GREENSBORO. AT LEAST 50 HOMES DAMAGED AND 10 DESTROYED PER EMA.
20:45 UTCTORNADO9 N GreensboroHale, ALPUBLIC REPORTS TORNADO ON THE GROUND CROSSING HIGHWAY 25 NORTH OF GREENSBORO.
20:48 UTCTORNADO2 Sw WateroakHale, ALTORNADO CROSSED RTE 69 AND CR 53...TREES DOWN OR SNAPPED...POWER LINES DOW.
20:48 UTCTORNADO8 Nne GreensboroHale, ALTORNADO CROSSED RTE 69 AND CR 53...TREES DOWN OR SNAPPED...POWER LINES DOW.
20:56 UTCTORNADON GreensboroHale, ALROOFS OFF OF HOUSES
20:59 UTCTORNADO 11 E MertzBibb, ALAN EF-1 TORNADO TOUCHED DOWN ALONG STATE HIGHWAY 25...3 MILES WEST OF COUNTY ROAD 16...WHERE THOUSANDS OF TREES WERE SNAPPED AND UPROOTED ALONG THE PATH. THERE WAS SOME STRUCTURE DAMAGE AS THE TORNADO CROSSED HIGHWAY 5 S
21:03 UTCTORNADOTuscaloosaTuscaloosa, ALSTRUCTURAL DAMAGE TO SKYLAND PARK AREA. TREES DOWN. HOUSES IMPACTED ON 10TH AVENUE EAST.
21:05 UTCTORNADOTuscaloosaTuscaloosa, ALSTUCTURAL DAMAGE TO SEVERAL HOMES IN THE BEACH HILL AREA.
21:09 UTCFLASH FLOODNorthportTuscaloosa, ALBRIDGE CLOSED ON HUNTER CREEK ROAD NEAR 28TH STREET DUE TO WATER OVERFLOWING IT.
21:12 UTCTORNADOMoundvilleHale, ALDAMAGE AT THE TOKYO RESTAURANT ON 69 SOUTH. SEVERAL TRAILER HOMES AT A DEALERSHIP TURNED OVER AND SPEEDY OIL CHANGE NORTH OF DEALERSHIP WAS HEAVILY DAMAGED. ON 82 SEVERAL TREES DOWN AND MOTEL 6 WAS HEAVILY DAMAGED.
21:14 UTCTORNADOW EolineBibb, ALTREES DOWN ON HWY 25. MULTIPLE TREES DOWN SOUTH OF LITTLE HOPE RD COMPLETELY BLOCKED. TREES DOWN ON HWY 82. TREE ACROSS ROAD ON HWY 5. FRIENDSHIP ROAD BLOCKED. ABOUT 10 TREES DOWN SOUTH OF 300. TREE DOWN ON EOLINE ROAD.
21:19 UTCTORNADOTuscaloosaTuscaloosa, ALSEVERAL TREES DOWN AND STRUCTURAL DAMAGE TO HOMES ON LOOP ROAD IN THE CIRCLEWOOD BAPTIST CHURCH VICINITY. HEAVY SMELL OF NATURAL GAS IN THE AIR.
21:23 UTCTORNADOEolineBibb, ALTREES AND POWERLINES DOWN ON HWY 82.
21:24 UTCTORNADOEolineBibb, ALLINES AND TREES SNAPPED AND SHREDDED. HWY 82 BLOCKED.
21:38 UTCTORNADO3 S West BloctonBibb, ALNUMEROUS TREES DOWN ON HWY 5.
21:44 UTCTORNADO 21 Ese ForklandGreene, ALAN EF-2 TORNADO TOUCHED DOWN THE TORNADO TOUCHED DOWN ABOUT 2.2 MILES EAST OF FORKLAND ALONG COUNTY ROAD 20. THE TORNADO MAINLY TRAVELED IN FOREST LAND SNAPPING AND UPROOTING THOUSANDS OF TREES. JUST NORTH OF GREENSBORO
21:45 UTCTORNADO5 N DemopolisGreene, ALTORNADO ON THE GROUND CROSSED HWY 43 5 MILES NORTH OF DEMOPOLIS.
21:50 UTCHAIL 1HelenaShelby, ALQUARTER SIZE HAIL IN ROCKY RIDGE AT JCT HWYS 17 AND 58.
21:58 UTCTSTM WND DMGHooverJefferson, ALLARGE MAGNOLIA TREE DOWN ALONG AL HWY 150 NEAR THE HOOVER MET.
21:59 UTCTORNADO 0AlabasterShelby, ALAN EF-0 TORNADO TOUCHED DOWN IN ALABASTER NEAR EVANGEL CHURCH ON THOMPSON RD LIFTING A FEW MINUTES LATER NEAR CITY HALL ON HWY 31. SEVERAL TREES WERE KNOCKED DOWN...SOME ON HOMES. THE PATH LENGTH WAS 1.36 MILES LONG WITH
22:00 UTCTSTM WND DMGAlabasterShelby, ALTREES DOWN ON A COUPLE OF HOMES ALONG HWY 31 NEAR THE FIRE STATION.
22:00 UTCTORNADOAlabasterShelby, ALTREES DOWN ON A COUPLE OF HOMES ALONG NEAR 8TH STREET SW NEAR THE FIRE STATION. LAW ENFORCEMENT WITNESSED THE TORNADO.
22:05 UTCTSTM WND DMGGreensboroHale, ALPOSSIBLE TORNADO. 20 TO 25 HOMES DAMAGED. ROADS CLOSED DUE TO MAJOR DAMAGE NORTH OF GREENSBORO. SEVERAL HUNDRED TREES DOWN IN THE COUNTY.
22:06 UTCFUNNEL CLOUDPelhamShelby, ALHAM ALERT TEAM MEMBER REPORTS A FUNNEL OVER HY 11 IN PELHAM.
22:10 UTCHAIL 1AlabasterShelby, ALQUARTER SIZE HAIL AT CITY HALL IN DOWNTOWN ALABASTER,
22:10 UTCHAIL 1AlabasterShelby, ALQUARTER SIZE HAIL IN ALABASTER.
22:11 UTCHAIL 0.5HooverJefferson, AL
22:17 UTCFLOODHooverJefferson, ALROAD FLOODING AT 1777 CHASE DRIVE IN HOOVER.
22:17 UTCFLASH FLOODHooverJefferson, ALROAD FLOODING AT 1777 CHASE DRIVE IN HOOVER.
22:17 UTCHAIL 1PelhamShelby, AL
22:20 UTCHAIL 1PelhamShelby, ALQUARTER SIZE HAIL OFF CR 52 IN DEERING DOWNS SUBDIVISION.
22:20 UTCHAIL 1PelhamShelby, ALQUARTER SIZE HIAL OFF CR 52 IN DEERING DOWNS SUBDIVISION.
22:25 UTCHAIL 11 S Shelby County AirpoShelby, ALNICKLE TO QUARTER SIZE HAIL REPORTED IN THE SCOTTSVILLE SUBDIVISION.

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

This ground now

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

The other tornadoes of April 15, 2011

74 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 151:13 AM CDTEF1Garland, AR7.3250$240,000
April 151:38 AM CDTEF1Saline, AR3.0250$40,000
April 151:47 AM CDTEF1Saline, AR16.9350$775,000
April 151:57 AM CDTEF1Pulaski, AR3.947522$39 million
April 152:01 AM CDTEF1Pulaski, AR6.6200$2.0 million
April 152:09 AM CDTEF1Pulaski, AR6.82001$455,000
April 152:17 AM CDTEF2Lonoke, AR7.0200$20 million
April 156:26 AM CDTEF0Issaquena, MS1.775$50,000
April 1510:11 AM CDTEF0Wayne, MS0.050
April 1510:51 AM CDTEF3Hinds, MS16.552810$8.0 million
April 1511:20 AM CDTEF1Clarke, AL3.3500$102,000
April 1511:22 AM CDTEF1Rankin, MS7.4200$6,000
April 1511:24 AM CDTEF0Choctaw, AL0.150$60,000
April 1511:26 AM CDTEF0Choctaw, AL4.7100$40,000
April 1511:41 AM CDTEF1Washington, MS to AL5.1200$312,000
April 1511:43 AM CDTEF1Rankin, MS7.6200$400,000
April 1511:48 AM CDTEF1Choctaw, AL16.7200$40,000
April 1511:58 AM CDTEF1Scott, MS7.0200$375,000
April 1512:04 PM CDTEF2Washington, AL0.91501$50,000
April 1512:53 PM CDTEF3Neshoba, MS to AL48.51,7605$19 million
April 151:35 PM CDTEF1Pike, MO3.050
April 151:39 PM CDTEF0Copiah, MS1.0200$2,000
April 151:47 PM CDTEF1Smith, MS3.8100$18,000
April 151:54 PM CDTEF1Holmes, MS6.1150$10,000
April 152:19 PM CDTEF2Attala, MS3.72002$35,000
April 152:23 PM CDTEF1Smith, MS6.9150$15,000
April 152:33 PM CDTEF0Attala, MS4.575
April 153:03 PM CDTEF2Sumter, AL4.5200$2.1 million
April 153:04 PM CDTEF1Jasper, MS1.2440$25,000
April 153:06 PM CDTEF1Monroe, AL0.8100
April 153:14 PM CDTEF3Greene, AL18.4500$7.1 million
April 153:33 PM CDTEF2Hale, AL2.2700$374,000
April 153:53 PM CDTEF2Sumter, AL8.9200$3.9 million
April 154:08 PM CDTEF1Clarke, MS to AL24.5470$200,000
April 154:35 PM CDTEF2Sumter, AL8.73251
April 154:44 PM CDTEF2Hale, AL24.1880$3.4 million
April 154:59 PM CDTEF1Jasper, MS1.6880$35,000
April 154:59 PM CDTEF0Shelby, AL1.450$15,000
April 155:04 PM CDTEF3Marengo, AL15.380014$4.0 million
April 155:11 PM CDTEF2Monroe, AL0.9150$200,000
April 155:19 PM CDTEF2Marengo, AL5.4575$1.0 million
April 155:29 PM CDTEF2Monroe, AL22.3300$390,000
April 155:30 PM CDTEF1Mason, IL3.11001$300,000
April 155:35 PM CDTEF2Marengo, AL10.9600$1.8 million
April 155:44 PM CDTEF1Shelby, AL4.4100$29,000
April 156:00 PM CDTEF0Perry, AL4.7150$23,000
April 156:12 PM CDTEF2Choctaw, AL38.8800$8.8 million
April 156:22 PM CDTEF0Menard, IL1.250$10,000
April 156:25 PM CDTEF2Perry, AL0.8500$38,000
April 156:25 PM CDTEF1Menard, IL1.7150$450,000
April 157:50 PM EDTEF0Harris, GA0.450$5,000
April 157:05 PM CDTEF1Dallas, AL0.175$21,000
April 157:23 PM CDTEF0Lowndes, AL2.775$21,000
April 157:45 PM CDTEF3Greene, MS to AL18.3500428$13 million
April 157:48 PM CDTEF1Dallas, AL0.2100$25,000
April 158:04 PM CDTEF1Dallas, AL1.6250$70,000
April 158:12 PM CDTEF0Trigg, KY0.350$8,000
April 158:14 PM CDTEF1Trigg, KY2.5125$30,000
April 158:48 PM CDTEF1Autauga, AL7.9200$440,000
April 158:56 PM CDTEF1Autauga, AL13.4200$458,000

All 75 of them

What this means

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.

Sources

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