Tornadoes · United States · Alabama · 2013

EF1 tornado, Harrisburg to Brierfield, Alabama, April 11, 2013

Name: EF1 tornado, Harrisburg to Brierfield, Alabama, April 11, 2013
Start: 2013-04-11T21:18:00.000Z
End: 2013-04-11T21:41:00.000Z
Location: Harrisburg to Brierfield, Alabama

From Harrisburg to Brierfield, this EF1 tornado ran 20.2 miles across Bibb County on April 11, 2013, touching down at 4:18 PM CDT and reaching 800 yards wide. It killed nobody.

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.

EF065 to 85 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mphthis tornado
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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 11, 2013
Touchdown: 4:18 PM CDT (21:18 UTC)
Lifted: 4:41 PM CDT (21:41 UTC)
On the ground: 23 minutes
Path length: 20.2 miles (32.4 km)
Path width: 800 yards (732 m)
Deaths: 0
Injuries: 0
County: Bibb County
Touchdown point: 32.846, -87.171
Lift-off point: 33.003, -86.879
Record number: 1304111518-01

The damage survey

9 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 90 mph.

Small section of siding torn off a house. 50 yards wide. Start point of Gully Creek EF-1 Tornado.
A few trees snapped and uprooted. 100 yards wide.
Numerous snapped and uprooted softwoods and hardwoods laying to the north. 200 yards wide. Worst tree damage noted at this location.
North edge of damage. Trees snapped and uprooted laying at 50 degrees.

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

Severe thunderstorms ahead of and along a cold front moved across Central Alabama on Thursday, April 11th. Storms along the cold front formed into a quasi-linear convective system, causing wind damage and producing seven tornadoes across the area. Ahead of the line, strong daytime heating and increasing instabilities coupled with strong diffluence aloft created prime conditions for discrete thunderstorms to form. These storms caused wind damage across portions of northeast Central Alabama during the late afternoon.

National Weather Service meteorologists surveyed damage in southern Bibb County and have determined that the damage was due to an EF-1 tornado, with winds of 90 mph. The tornado touched down near the intersection of Abercrombie Road (County Road 51) and Harrisburg Road in the Talladega National Forest of southern Bibb County. The only structural damage occurred at the beginning of the path where a home had siding torn off. Otherwise, the damage was confined to trees. The tornado strengthened as it paralleled County Road 51, snapping or uprooting numerous trees about 3 miles along the path. The tornado continued northeast and crossed Highway 219 and Highway 82. The tornado weakened as it continued northeast across Antioch Road (County Road 20) and Highway 139. The tornado eventually lifted immediately west of the Chilton County Line on County Road 2.

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

What forecasters said that day

The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Birmingham, AL wrote its last area forecast discussion before the tornado touched down at Apr 11, 3:59 PM CDT, 19 minutes earlier.

Area forecast discussion, Apr 11, 3:59 PM CDT, 19 minutes before

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Hazardous weather outlook, Apr 11, 2:55 PM CDT, 1 hour 23 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BIRMINGHAM AL
255 PM CDT THU APR 11 2013

ALZ011>015-017>050-121955-
MARION-LAMAR-FAYETTE-WINSTON-WALKER-BLOUNT-ETOWAH-CALHOUN-CHEROKEE-
CLEBURNE-PICKENS-TUSCALOOSA-JEFFERSON-SHELBY-ST. CLAIR-TALLADEGA-
CLAY-RANDOLPH-SUMTER-GREENE-HALE-PERRY-BIBB-CHILTON-COOSA-
TALLAPOOSA-CHAMBERS-MARENGO-DALLAS-AUTAUGA-LOWNDES-ELMORE-
MONTGOMERY-MACON-BULLOCK-LEE-RUSSELL-PIKE-BARBOUR-
255 PM CDT THU APR 11 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE COUNTIES SERVED BY THE
NATIONAL WEATHER SERVICE OFFICE IN BIRMINGHAM.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SEVERE WEATHER CHANCES ARE TWO FOLD TODAY. FIRST...SEVERE
THUNDERSTORMS ARE POSSIBLE ACROSS ALL OF CENTRAL ALABAMA THROUGH
TONIGHT AS A LINE OF SHOWERS AND THUNDERSTORMS AHEAD OF A FRONT MOVE
WEST TO EAST ACROSS THE AREA. LOOK FOR THE ACTIVITY TO PROGRESS
ACROSS THE WEST HALF OF THE STATE THROUGH SUNSET AND CONTINUE INTO
THE EASTERN HALF THROUGH MIDNIGHT. SECOND...DISCRETE SUPERCELLS MAY
DEVELOP DURING THE REMAINDER OF THE AFTERNOON AND EVENING HOURS
AHEAD OF THE LINE ACROSS CENTRAL ALABAMA WITH THE BEST CHANCES
GENERALLY ALONG AND EAST OF INTERSTATE 65.  DAMAGING WINDS...
TORNADOES...LOCALLY HEAVY RAIN AND HAIL WILL ALL BE POSSIBLE AS THE
STORM SYSTEM SLIDES THROUGH THE AREA.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

MINOR RIVER FLOODING IS FORECAST TO OCCUR ALONG THE TOMBIGBEE RIVER
FOR FRIDAY INTO SUNDAY. PLEASE SEE THE LATEST RIVER STATEMENT FOR
DETAILS.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT WILL BE
NEEDED THROUGH TONIGHT.

08

In the hours before

Local storm report, Apr 11, 3:30 PM CDT, 48 minutes before

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Local storm report, Apr 11, 3:42 PM CDT, 36 minutes before

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Special weather statement, Apr 11, 3:43 PM CDT, 35 minutes before

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Local storm report, Apr 11, 3:56 PM CDT, 22 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
356 PM CDT THU APR 11 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0325 PM     TSTM WND DMG     1 N NESMITH             34.20N 87.12W
04/11/2013                   WINSTON            AL   EMERGENCY MNGR

            UNKNOWN STRUCTURAL DAMAGE ALONG CR 45 NEAR CR 3734 WITH
            POSSIBLE INJURIES. TIME ESTIMATED FROM RADAR.

&&

TGOGGINS

Local storm report, Apr 11, 3:57 PM CDT, 21 minutes before

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE BIRMINGHAM AL
357 PM CDT THU APR 11 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1257 PM     TORNADO          4 SSW ETHELSVILLE       33.35N 88.24W
04/11/2013                   PICKENS            AL   TRAINED SPOTTER

            TREES AND POWER LINES DOWN ALONG PINE GROVE ROAD NEAR THE
            PINE GROVE COMMUNITY. STATE POLICE REPORT DAMAGE TO ONE
            HOUSE AND POSSIBLY A SECOND HOUSE...AND A LARGE NUMBER OF
            TREES DOWN ALONG CR 75. RADAR INDICATED TORNADO.

0200 PM     TSTM WND DMG     1 E FAYETTE             33.69N 87.82W
04/11/2013                   FAYETTE            AL   EMERGENCY MNGR

            POWER LINES DOWN ALONG 7TH STREET NE AND ALSO ACROSS FROM
            WALMART. TIME ESTIMATED FROM RADAR.

0203 PM     TSTM WND DMG     FAYETTE                 33.69N 87.83W
04/11/2013                   FAYETTE            AL   BROADCAST MEDIA

            A TREE AND POWER POLE BLOWN DOWN ON 7TH STREET SE.

0230 PM     TSTM WND DMG     3 SE GLEN ALLEN         33.89N 87.70W
04/11/2013                   FAYETTE            AL   EMERGENCY MNGR

            TREE DOWN ON HOUSE ALONG CR 53N. TIME ESTIMATED FROM
            RADAR.

0243 PM     TSTM WND DMG     4 WNW CARBON HILL       33.91N 87.59W
04/11/2013                   WALKER             AL   PUBLIC

            TREES DOWN BLOCKING ROAD NEAR INTERSECTION OF NAUVOO AND
            NIX ROADS. TIME ESTIMATED FROM RADAR.

0325 PM     TSTM WND DMG     1 N NESMITH             34.20N 87.12W
04/11/2013                   WINSTON            AL   EMERGENCY MNGR

            UNKNOWN STRUCTURAL DAMAGE ALONG CR 45 NEAR CR 3734 WITH
            POSSIBLE INJURIES. TIME ESTIMATED FROM RADAR.

0338 PM     HAIL             6 N JASPER              33.94N 87.27W
04/11/2013  E0.25 INCH       WALKER             AL   PUBLIC

            PEA SIZE HAIL AND HIGH WINDS IN THE FARMSTEAD COMMUNITY.

&&

Local storm report, Apr 11, 4:13 PM CDT, 5 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
413 PM CDT THU APR 11 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0359 PM     TSTM WND DMG     3 NNW TALLADEGA         33.47N 86.12W
04/11/2013                   TALLADEGA          AL   EMERGENCY MNGR

            POWER LINES DOWN ON PETERS ROAD OFF HWY 77.

&&

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

9.3 hours before the tornado, 36 km from the path. April 11, 2013.

Skew-T log-p

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.

Hodograph

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: 35 J/kg
Mixed-layer CIN: -291 J/kg
Surface CAPE: 0 J/kg
Mixed-layer LCL: 635 m above ground
0-6 km bulk shear: 31 kt
0-1 km bulk shear: 28 kt
0-1 km storm-relative helicity: 143 m²/s²
0-3 km storm-relative helicity: 169 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0
0-3 km lapse rate: 4.2 K/km

Open this sounding in Storm Lab

The surface observations

Alabaster (EET), 36 km from the path, in the two hours either side.

Time (UTC)	Temp (°F)	Dew point (°F)	Wind	Gust (kt)	Pressure (mb)	Weather
00:00 UTC

From the Iowa Environmental Mesonet's archive of airport observations.

The radar

The Birmingham radar (KBMX), 36 km away, was scanning. The volume nearest the touchdown began at 21:18 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.

This ground now

The live radar over the track Every 2013 tornado in Alabama Every tornado in Alabama since 1950 Warnings in force in Alabama now The forecast where you are

The other tornadoes of April 11, 2013

13 more were confirmed in the United States that day.

Date	Time	Rating	Where	Path (mi)	Width (yd)	Deaths	Injuries	Damage
April 11	11:35 AM CDT	EF3	Kemper, MS to AL	66.3	1,320	1	9	$1.2 million
April 11	1:05 PM CDT	EF1	Saint Tammany Parish, LA	8.8	120			$100,000
April 11	2:45 PM CDT	EF1	Walker, AL	5.5	500
April 11	2:57 PM CDT	EF1	Winston, AL	2.6	250
April 11	3:10 PM CDT	EF1	Winston, AL	1.2	300
April 11	3:26 PM CDT	EF1	Winston, AL	0.4	50		1
April 11	4:20 PM CDT	EF1	Madison, AL	6.6	300
April 11	4:32 PM CDT	EF1	Madison, AL	1.3	75
April 11	6:23 PM EDT	EF0	Haralson, GA	5.7	150			$30,000
April 11	5:29 PM CDT	EF1	Mobile, AL	0.8	75			$1.5 million
April 11	7:01 PM EDT	EF0	Polk, GA	0.4	25			$15,000
April 11	9:23 PM EDT	EF1	Lumpkin, GA	4.1	250			$325,000
April 11	8:34 PM CDT	EF2	Macon, AL	5.1	200		1

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.