Tornadoes · United States · Missouri · 2007

EF0 tornado, Roby, Missouri, August 20, 2007

This EF0 tornado ran 0.1 miles across Texas County on August 20, 2007, touching down at 2:45 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 mphthis tornado

    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. 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
EF0
Date
August 20, 2007
Touchdown
2:45 PM CDT (19:45 UTC)
Lifted
2:46 PM CDT (19:46 UTC)
On the ground
1 minutes
Path length
0.1 miles (0.2 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
County
Texas County
Touchdown point
37.520, -92.095
Lift-off point
37.520, -92.095
Record number
0708201345-01

What the Weather Service recorded

The remnants of Tropical Storm Erin produced significant flash flooding along a line from northern Jasper County to northern Laclede County. Numerous roads were washed out across Lawrence, Greene, Polk, Dallas, and Webster counties. This prompted several water rescues. One man was killed in Laclede County as he attempted to cross a section of a road that had been washed out from flood water.

A National Weather Service storm survey revealed that an EF-0 tornado briefly touched down in a rural area three miles east of Roby. A few trees experienced minor damage.

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

The warnings

8 minutes of warning. NWS SGF issued a tornado warning for this county at 19:37 UTC, 8 minutes before the tornado touched down, in force until 20:15 UTC.

Issued (UTC)ExpiredProductOffice
18:31 UTC03:00 UTCFlash Flood WarningSGF
19:37 UTC20:15 UTCTornado WarningSGF
20:41 UTC22:00 UTCSevere Thunderstorm WarningSGF

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 General Thunderstorms Risk. The outlook in force was issued at 16:27 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.

Springfield, MO (KSGF), 12:00Z

7.8 hours before the tornado, 166 km from the path. August 20, 2007.

Skew-T log-pSkew-T log-p diagram, Springfield, MO at 12:00Z on 2007-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 671 joules per kilogram, CIN -30, lifted condensation level 560 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, Springfield, MO at 12:00Z on 2007-08-20The 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 225 square meters per square second, 0 to 6 km bulk shear 38 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
671 J/kg
Mixed-layer CIN
-30 J/kg
Surface CAPE
320 J/kg
Mixed-layer LCL
560 m above ground
0-6 km bulk shear
38 kt
0-1 km bulk shear
49 kt
0-1 km storm-relative helicity
225 m²/s²
0-3 km storm-relative helicity
254 m²/s²
Significant tornado parameter
0.6
Supercell composite
8.4
0-3 km lapse rate
4.9 K/km

Open this sounding in Storm Lab

Springfield, MO (KSGF), 00:00Z

4.2 hours after it, 166 km from the path. August 21, 2007.

Skew-T log-pSkew-T log-p diagram, Springfield, MO at 00:00Z on 2007-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 2097 joules per kilogram, CIN -7, lifted condensation level 1187 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, Springfield, MO at 00:00Z on 2007-08-21The 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 43 square meters per square second, 0 to 6 km bulk shear 21 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
2097 J/kg
Mixed-layer CIN
-7 J/kg
Surface CAPE
3265 J/kg
Mixed-layer LCL
1187 m above ground
0-6 km bulk shear
21 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
43 m²/s²
0-3 km storm-relative helicity
147 m²/s²
Significant tornado parameter
0.8
Supercell composite
7.2
0-3 km lapse rate
6.7 K/km

Open this sounding in Storm Lab

The radar

The Springfield radar (KSGF), 120 km away, was scanning. The volume nearest the touchdown began at 19:45 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
17:25 UTCFLASH FLOODLebanonLaclede, MOROAD FLOODED. EAST HIGHWAY 32 NEAR PINETREE IN THE LEBANON AREA.
18:00 UTCFLASH FLOODLebanonLaclede, MOWEST ELM ROAD IS CLOSED BETWEEN DRURY AND SPRINGFIELD ROAD IN LEBANON DUE TO FLOOD WATERS.
19:05 UTCFUNNEL CLOUDFalconLaclede, MO
19:15 UTCTSTM WND DMG5 Sw FalconLaclede, MOSEVERE THUNDERSTORM WIND GUSTS DOWNED A FEW TREES NEAR NEBO.
19:40 UTCTSTM WND DMG2 W LynchburgLaclede, MOSEVERE THUNDERSTORM WIND GUSTS DOWNED A FEW TREES WEST OF LYNCHBURG.
19:45 UTCTORNADO3 E RobyTexas, MOTHE PUBLIC REPORTED A BRIEF TORNADO TOUCHDOWN. A NWS SURVEY INDICATED SOME TREE DAMAGE IN THE AREA. BRIEF TOUCHDOWN WITH A 50 YARD WIDE DAMAGE PATH. EF-0. MOST OF THE SHORT PATH WAS IN AN OPEN FIELD.
19:46 UTCFLASH FLOOD7 S Wet GlaizeCamden, MOLOW WATER CROSSINGS AT ROUTE BB JUST SOUTH OF HIGHWAY 7 AND ROUTE H WEST OF ROUTE T WERE FLOODED AND IMPASSABLE.
20:00 UTCFLASH FLOOD4 Nnw SleeperLaclede, MOROUTE BB, NORTHWEST OF SLEEPER AND NORTH OF ROUTE F IS CLOSED DUE TO FLOOD WATERS.
20:32 UTCFLASH FLOOD3 Nw FalconLaclede, MOFLASH FLOODING IS INUNDATING THE INTERSECTION OF HIGHWAYS 32 AND K. THIS INTERSECTION IS IMPASSABLE TO MOTORISTS.
22:26 UTCFLASH FLOOD6 Ne WaynesvillePulaski, MOEVACUATING THE GASCONADE HILLS RESORT. WATER RAPIDLY RISING.
22:30 UTCFLASH FLOOD2 Se StoutlandLaclede, MOINTERSECTION OF ROUTE T AND FF CLOSED DUE TO FLOODING
22:30 UTCFLASH FLOOD3 Nw SleeperLaclede, MOINTERSECTION OF ROUTE BB AND F CLOSED DUE TO FLOODING
22:30 UTCFLASH FLOOD3 Sw WaynesvillePulaski, MOROUTE H 2 MILES SOUTH OF INTERSTATE 44 CLOSED DUE TO FLOODING
22:30 UTCFLASH FLOOD6 Nw Dry KnobLaclede, MOOUTER ROAD OF INTERSTATE 44 AT ROUTE N CLOSED DUE TO FLOODING

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

This ground now

The live radar over the trackEvery 2007 tornado in MissouriEvery tornado in Missouri since 1950Warnings in force in Missouri nowThe forecast where you are

The other tornadoes of August 20, 2007

2 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 202:55 PM EDTEF1Richland, OH4.950$150,000
August 206:35 PM CDTEF0Colfax, NE5.3100

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.