Tornadoes · United States · Texas · 2018

Unrated tornado, Oakalla, Texas, April 6, 2018

This Unrated tornado ran 0.6 miles across Burnet County on April 6, 2018, touching down at 7:51 PM CDT and reaching 50 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 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 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. Unratedthis tornado

    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
Unrated
Date
April 6, 2018
Touchdown
7:51 PM CDT (00:51 UTC)
Lifted
7:54 PM CDT (00:54 UTC)
On the ground
3 minutes
Path length
0.6 miles (0.9 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
County
Burnet County
Touchdown point
30.980, -98.020
Lift-off point
30.980, -98.010
Record number
1804061851-01

What the Weather Service recorded

Thunderstorms developed as a cold front moved into a warm, moist airmass. A few of these storms produced severe hail and a short lived tornado.

A trained spotter reported a tornado northwest of Briggs north of US 183 in northeastern Burnet County. The tornado was short lived and there wasn't any damage reported.

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

The warnings

1 minute of warning. NWS EWX issued a tornado warning for this county at 00:50 UTC, 1 minute before the tornado touched down, in force until 01:15 UTC.

Issued (UTC)ExpiredProductOffice
00:34 UTC01:15 UTCSevere Thunderstorm WarningEWX
00:50 UTC01:15 UTCTornado WarningEWX

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 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 19:50 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.

Fort Worth, TX (KFWD), 00:00Z

0.9 hours before the tornado, 217 km from the path. April 7, 2018.

Skew-T log-pSkew-T log-p diagram, Fort Worth, TX at 00:00Z on 2018-04-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 690 joules per kilogram, CIN -42, lifted condensation level 1896 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°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, Fort Worth, TX at 00:00Z on 2018-04-07The 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 -40 square meters per square second, 0 to 6 km bulk shear 18 knots.193958Sfc1 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
690 J/kg
Mixed-layer CIN
-42 J/kg
Surface CAPE
2914 J/kg
Mixed-layer LCL
1896 m above ground
0-6 km bulk shear
18 kt
0-1 km bulk shear
14 kt
0-1 km storm-relative helicity
-40 m²/s²
0-3 km storm-relative helicity
44 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.2
0-3 km lapse rate
6.9 K/km

Open this sounding in Storm Lab

Fort Worth, TX (KFWD), 12:00Z

11.1 hours after it, 217 km from the path. April 7, 2018.

Skew-T log-pSkew-T log-p diagram, Fort Worth, TX at 12:00Z on 2018-04-07Temperature 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 0, lifted condensation level 485 meters above ground. Wind barbs in knots down the right edge.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°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, Fort Worth, TX at 12:00Z on 2018-04-07The 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 109 square meters per square second, 0 to 6 km bulk shear 35 knots.1939587897Sfc1 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
0 J/kg
Surface CAPE
10 J/kg
Mixed-layer LCL
485 m above ground
0-6 km bulk shear
35 kt
0-1 km bulk shear
24 kt
0-1 km storm-relative helicity
109 m²/s²
0-3 km storm-relative helicity
602 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6
0-3 km lapse rate
1.4 K/km

Open this sounding in Storm Lab

The radar

The Ft Hood radar (KGRK), 67 km away, was scanning. The volume nearest the touchdown began at 00:49 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
00:51 UTCTORNADO8 Nw BriggsBurnet, TXTRAINED SPOTTER REPORTS TORNADO NW OF BRIGGS JUST NORTH OF US 183 IN NORTHEASTERN BURNET COUNTY.
00:55 UTCHAIL 1.758 N BriggsBurnet, TXDELAYED REPORT OF GOLF BALL SIZED HAIL IN NORTHEASTERN BURNET COUNTY.
00:58 UTCHAIL 17 E LampasasLampasas, TX$$
03:34 UTCHAIL 0.75BeltonBell, TXNEAR THE JUNCTION OF I-14 AND I-35
03:40 UTCHAIL 1BeltonBell, TXNEAR THE JUNCTION OF I-14 AND I-35

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

This ground now

The live radar over the trackEvery 2018 tornado in TexasEvery tornado in Texas since 1950Warnings in force in Texas nowThe forecast where you are

The other tornadoes of April 6, 2018

12 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 66:05 PM CDTEF0Madison Parish, LA1.125
April 66:40 PM CDTEF0Richland Parish, LA7.850$15,000
April 67:31 PM CDTEF2Red River Parish, LA10.11,800$225,000
April 68:03 PM CDTEF0Rankin, MS2.625$15,000
April 68:12 PM CDTEF1Warren, MS2.875$15,000
April 69:14 PM CDTEF1Natchitoches Parish, LA0.750$6,000
April 69:27 PM CDTEF1Claiborne, MS1.2360$25,000
April 69:32 PM CDTEF1Claiborne, MS5.8880$200,000
April 69:46 PM CDTEF1Copiah, MS2.4700$20,000
April 611:01 PM CDTEF1Jefferson Davis, MS4.7350$25,000
April 611:18 PM CDTEF1Jefferson Davis, MS2.9440$60,000
April 611:33 PM CDTEF1Covington, MS1.7125$30,000

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.