Tornadoes · United States · Alabama · 2017

EF1 tornado, River Bend to Blocton Jct, Alabama, August 31, 2017

From River Bend to Blocton Jct, this EF1 tornado ran 0.6 miles across Bibb County on August 31, 2017, touching down at 7:28 PM CDT and reaching 200 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.

  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
August 31, 2017
Touchdown
7:28 PM CDT (00:28 UTC)
Lifted
7:30 PM CDT (00:30 UTC)
On the ground
2 minutes
Path length
0.6 miles (0.9 km)
Path width
200 yards (183 m)
Deaths
0
Injuries
0
County
Bibb County
Touchdown point
33.101, -87.172
Lift-off point
33.107, -87.165
Record number
1708311828-01

The damage survey

59 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 95 mph.

  • looking west. approx come from 220 deg
  • looking east. healthy tree uprooted.
  • roughly 300 degrees. trees snapped/uprooted
  • roof detached tossed behind shed

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

The remnants of Hurricane Harvey tracked northeast across Louisiana and along the Mississippi River. Feeder bands on the east side of Harvey produced four tornadoes across central Alabama.

NWS meteorologists surveyed damage in northern Bibb County and determined that the damage was consistent with an EF1 tornado. The tornado spun up along a hunting road south of Hopewell Church Road, where a couple of trees were downed. It paralleled Hopewell Church Road and reached its greatest intensity near a pond. Numerous trees were snapped and uprooted on both sides of the pond. The tornado dissipated north of the pond, prior to reaching Hopewell Church Road.

NWS meteorologists surveyed damage in northern Bibb County and determined that the damage was consistent with an EF0 tornado. The tornado developed just south of Old Woodstock Road along the northern side of the Colonial Pipeline with light tree damage observed. The tornado briefly intensified as it crossed Old Woodstock Road, uprooting several trees. Another batch of uprooted trees was seen toward the northeast, as the tornado moved through a stand of trees. The circulation then quickly weakened roughly 1.5 miles south of the Tuscaloosa County line.

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

The warnings

33 minutes of warning. NWS BMX issued a tornado warning for this county at 23:55 UTC, 33 minutes before the tornado touched down, in force until 01:00 UTC.

The county was under a tornado watch, issued at 16:15 UTC and running to 03:00 UTC.

Issued (UTC)ExpiredProductOffice
16:15 UTC03:00 UTCTornado WatchBMX
23:55 UTC01:00 UTCTornado WarningBMX
00:12 UTC00:33 UTCTornado WarningBMX
01:31 UTC03:30 UTCFlood AdvisoryBMX
01:39 UTC23:00 UTCWind AdvisoryBMX
01:41 UTC02:30 UTCSevere Thunderstorm WarningBMX

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 Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:57 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), 00:00Z

0.5 hours before the tornado, 37 km from the path. September 1, 2017.

Skew-T log-pSkew-T log-p diagram, Birmingham, AL at 00:00Z on 2017-09-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 545 joules per kilogram, CIN -7, lifted condensation level 1112 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 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 00:00Z on 2017-09-01The 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 258 square meters per square second, 0 to 6 km bulk shear 41 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
545 J/kg
Mixed-layer CIN
-7 J/kg
Surface CAPE
1975 J/kg
Mixed-layer LCL
1112 m above ground
0-6 km bulk shear
41 kt
0-1 km bulk shear
29 kt
0-1 km storm-relative helicity
258 m²/s²
0-3 km storm-relative helicity
347 m²/s²
Significant tornado parameter
0.6
Supercell composite
11.0
0-3 km lapse rate
6.9 K/km

Open this sounding in Storm Lab

Birmingham, AL (KBMX), 12:00Z

11.5 hours after it, 37 km from the path. September 1, 2017.

Skew-T log-pSkew-T log-p diagram, Birmingham, AL at 12:00Z on 2017-09-01Temperature 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 -70240, lifted condensation level 797 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 2017-09-01The 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 89 square meters per square second, 0 to 6 km bulk shear 35 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
-70240 J/kg
Surface CAPE
6 J/kg
Mixed-layer LCL
797 m above ground
0-6 km bulk shear
35 kt
0-1 km bulk shear
28 kt
0-1 km storm-relative helicity
89 m²/s²
0-3 km storm-relative helicity
116 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.8 K/km

Open this sounding in Storm Lab

The surface observations

Bessemer (EKY), 32 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
22:30 UTC150° 10 kt1009.5
22:35 UTC160° 9 kt141009.5
22:39 UTC78.871.6150° 10 kt151009.5TS
22:40 UTC160° 10 kt161009.5
22:45 UTC160° 8 kt1009.5
22:50 UTC160° 9 kt141009.5
22:54 UTC80.671.6150° 10 kt161009.5
22:55 UTC150° 10 kt1009.5
22:56 UTC8072160° 10 kt161009.5
23:00 UTC160° 10 kt1009.1
23:05 UTC150° 9 kt1009.1
23:10 UTC150° 9 kt151009.1
23:15 UTC150° 11 kt161009.1
23:20 UTC150° 9 kt1009.1
23:25 UTC180° 8 kt1008.8
23:30 UTC160° 9 kt1008.8
23:35 UTC160° 10 kt151008.8
23:40 UTC150° 8 kt1008.5
23:45 UTC160° 9 kt1008.5
23:50 UTC150° 9 kt1008.5
23:55 UTC150° 11 kt1008.1
23:56 UTC8072150° 11 kt191008.1
00:00 UTC150° 10 kt1008.1
00:05 UTC150° 12 kt1008.1
00:10 UTC150° 10 kt1008.1
00:20 UTC150° 11 kt161007.8-RA
00:25 UTC150° 10 kt1007.8-RA
00:30 UTC150° 14 kt191007.8
00:35 UTC160° 12 kt181007.8-RA
00:39 UTC78.871.6160° 10 kt221007.8VCTS RA
00:40 UTC150° 10 kt161007.8RA
00:45 UTC150° 12 kt1007.8RA
00:50 UTC150° 12 kt1007.5-RA
00:55 UTC160° 10 kt1007.5-RA
00:56 UTC7872160° 9 kt211007.5TSRA
01:00 UTC150° 10 kt1007.5RA
01:05 UTC150° 11 kt1007.1-RA
01:10 UTC160° 11 kt1007.1-RA
01:15 UTC130° 11 kt1007.1-RA
01:20 UTC 211007.8-RA
01:25 UTC240° 14 kt1008.5-RA
01:26 UTC75.273.4230° 12 kt251008.5TSRA BR
01:30 UTC220° 6 kt1007.8+RA BR
01:35 UTC220° 9 kt161008.1-RA BR
01:40 UTC240° 11 kt1008.5RA
01:45 UTC170° 5 kt1008.1+RA
01:50 UTC 1009.1+RA BR
01:55 UTC210° 10 kt151009.1+RA BR
01:56 UTC7474200° 10 kt231009.1TSRA BR
02:00 UTC 1009.1RA BR
02:05 UTC 1009.1+RA BR
02:10 UTC 1008.8+RA BR
02:12 UTC71.671.6200° 16 kt271008.8TSRA
02:15 UTC 201009.1RA
02:20 UTC190° 12 kt181009.1-RA
02:25 UTC71.671.6180° 9 kt191009.1VCTS -RA

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

The radar

The Birmingham radar (KBMX), 38 km away, was scanning. The volume nearest the touchdown began at 00:30 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
23:57 UTCTORNADO1 Se HarmonBibb, ALNWS METEOROLOGISTS SURVEYED DAMAGE IN SOUTHWEST BIBB COUNTY AND FOUND THAT THE DAMAGE WAS CONSISTENT WITH AN EF1 TORNADO, WITH MAXIMUM SUSTAINED WINDS NEAR 90. NO INJURIES OR FATALITIES.
00:09 UTCTSTM WND DMG2 Wsw EolineBibb, ALTREES AND POWER LINES DOWN ACROSS PORTIONS OF WARD SCHOOL ROAD, WEST EOLINE ROAD AND BEAR CREEK ROAD. POSSIBLE TORNADO. REPORT RELAYED BY SOCIAL MEDIA. LOCATION APPROXIMATE.
00:11 UTCTORNADO1 Se HarmonBibb, ALSTORM CHASER TOOK VIDEO OF TORNADO CROSSING U.S. HIGHWAY 82 IN BIBB COUNTY NEAR EOLINE. TIME APPROXIMATE.
00:28 UTCTORNADO3 Wsw West BloctonBibb, ALNWS METEOROLOGISTS SURVEYED DAMAGE NEAR HOPEWELL CHURCH ROAD AND DETERMINED THAT IT WAS CAUSED BY AN EF1 TORNADO WITH 95 MPH WINDS.
00:42 UTCTORNADO1 E North BibbBibb, ALNWS METEOROLOGISTS SURVEYED DAMAGE NEAR OLD WOODSTOCK ROAD AND DETERMINED THAT IT WAS CAUSED BY AN EF0 TORNADO WITH 75 MPH WINDS.
01:55 UTCTSTM WND DMG1 Nw AlabasterShelby, ALTREE DOWN AT HIGHWAY 95 AND BIG CLOUD CIRCLE.
02:56 UTCTSTM WND DMG1 S ShelbyShelby, ALTREE DOWN AT COUNTY 46 AND COUNTY 47.

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

This ground now

The live radar over the trackEvery 2017 tornado in AlabamaEvery tornado in Alabama since 1950Warnings in force in Alabama nowThe forecast where you are

The other tornadoes of August 31, 2017

15 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 318:19 AM CDTEF0Phillips, AR1.750$15,000
August 3111:57 AM CDTEF0Benton, MS0.330$25,000
August 311:13 PM CDTEF0Lee, MS1.140
August 311:23 PM CDTEF1Itawamba, MS2.5150$150,000
August 311:43 PM CDTEF0Prentiss, MS0.330$50,000
August 313:07 PM CDTEF0Hardin, TN1.350$10,000
August 313:40 PM CDTEF2Pickens, AL31.26006
August 314:19 PM CDTEF0Perry, TN0.350$10,000
August 314:37 PM CDTEF0Hardin, TN0.870$10,000
August 315:11 PM CDTEF0Maury, TN3.475$10,000
August 316:57 PM CDTEF1Bibb, AL6.5100
August 317:42 PM CDTEF0Bibb, AL0.335
August 318:58 PM CDTEF2Cullman, AL13.6300
August 3111:21 PM CDTEF1Davidson, TN0.675$25,000
August 3111:47 PM CDTEF0Davidson, TN0.950$15,000

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.