Tornadoes · United States · Missouri · 2013

EF0 tornado, Gerster, Missouri, May 20, 2013

This EF0 tornado ran 0.5 miles across St. Clair County on May 20, 2013, touching down at 6:56 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 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
May 20, 2013
Touchdown
6:56 PM CDT (23:56 UTC)
Lifted
6:57 PM CDT (23:57 UTC)
On the ground
1 minutes
Path length
0.5 miles (0.8 km)
Path width
200 yards (183 m)
Deaths
0
Injuries
0
County
St. Clair County
Touchdown point
37.938, -93.636
Lift-off point
37.939, -93.627
Record number
1305201756-01

What the Weather Service recorded

A strong negatively titled upper level trough developed over the central portions of the country. A slow moving cold front moved into the Missouri Ozarks. This setup caused for several rounds of severe and slow moving thunderstorms which lead to widespread wind damage, large hail, and several low end tornadoes along with isolated flooding due to heavy rainfall.

An EF-0 tornado produced up to 80 mph winds and uprooted trees along a half mile long path.

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

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

The county was under a tornado watch, issued at 17:49 UTC and running to 01:37 UTC.

Issued (UTC)ExpiredProductOffice
17:49 UTC01:37 UTCTornado WatchSGF
20:16 UTC20:35 UTCSevere Thunderstorm WarningSGF
23:11 UTC23:29 UTCSevere Thunderstorm WarningSGF
23:47 UTC00:30 UTCSevere Thunderstorm WarningSGF
01:00 UTC04:09 UTCFlash Flood WatchSGF

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 0.10 chance of a tornado within 25 miles. The outlook in force was issued at 19:58 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

11.9 hours before the tornado, 116 km from the path. May 20, 2013.

Skew-T log-pSkew-T log-p diagram, Springfield, MO at 12:00Z on 2013-05-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 4 joules per kilogram, CIN -445, lifted condensation level 1092 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 2013-05-20The 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 81 square meters per square second, 0 to 6 km bulk shear 69 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
4 J/kg
Mixed-layer CIN
-445 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1092 m above ground
0-6 km bulk shear
69 kt
0-1 km bulk shear
17 kt
0-1 km storm-relative helicity
81 m²/s²
0-3 km storm-relative helicity
208 m²/s²
Significant tornado parameter
0.0
Supercell composite
4.4
0-3 km lapse rate
3.5 K/km

Open this sounding in Storm Lab

Springfield, MO (KSGF), 00:00Z

0.1 hours after it, 116 km from the path. May 21, 2013.

Skew-T log-pSkew-T log-p diagram, Springfield, MO at 00:00Z on 2013-05-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 2135 joules per kilogram, CIN -10, lifted condensation level 780 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 2013-05-21The 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 236 square meters per square second, 0 to 6 km bulk shear 49 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
2135 J/kg
Mixed-layer CIN
-10 J/kg
Surface CAPE
2535 J/kg
Mixed-layer LCL
780 m above ground
0-6 km bulk shear
49 kt
0-1 km bulk shear
31 kt
0-1 km storm-relative helicity
236 m²/s²
0-3 km storm-relative helicity
265 m²/s²
Significant tornado parameter
3.2
Supercell composite
13.9
0-3 km lapse rate
5.7 K/km

Open this sounding in Storm Lab

The radar

The Springfield radar (KSGF), 81 km away, was scanning. The volume nearest the touchdown began at 23:57 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
22:37 UTCTORNADO3 S StocktonCedar, MOAN EF-0 TORNADO TOUCHED DOWN ABOUT 3 MILES SOUTH OF STOCKTON ALONG EAST 1674 ROAD. THIS TORNADO CONTINUED ON A 2.1 MILE LONG PATH THROUGH ORLEANS TRAIL PUBLIC USE AREA BEFORE LIFTING OVER STOCKTON LAKE. THERE WAS DAMAGE
23:34 UTCTSTM WND DMG2 Nnw WagonerCedar, MOBARN BLOWN INTO TRAILER HOME AND DAMAGED TRAILER.
23:37 UTCTORNADO3 S StocktonCedar, MOAN EF-0 TORNADO TOUCHED DOWN ABOUT 3 MILES SOUTH OF STOCKTON ALONG EAST 1674 ROAD. THIS TORNADO CONTINUED ON A 2.1 MILE LONG PATH THROUGH ORLEANS TRAIL PUBLIC USE AREA BEFORE LIFTING OVER STOCKTON LAKE. THERE WAS DAMAGE
23:43 UTCTSTM WND DMG5 Nnw StocktonCedar, MOROOF DAMAGE TO TRAILER HOME.
23:43 UTCTSTM WND DMGStocktonCedar, MOTREES AND POWER LINES REPORTED DOWN THROUGHOUT THE COUNTY.
23:56 UTCTORNADO3 Nnw CollinsSt. Clair, MOAN EF-0 TORNADO PRODUCED UP TO 80 MPH WINDS AND UPROOTED TREES ALONG A HALF MILE LONG AND 200 YARD WIDE PATH.
23:57 UTCTSTM WND DMGCollinsSt. Clair, MOTREES REPORTED DOWN.
23:57 UTCTSTM WND DMGWeaubleauHickory, MOREPORTS OF DAMAGE TO ROOF OF CITY HALL.
00:02 UTCTSTM WND DMG6 Se OsceolaSt. Clair, MOEMERGENCY MANAGER REPORTS HUNDREDS OF TREES DOWN THROUGHOUT THE EASTERN PORTION OF ST. CLAIR COUNTY DUE TO STRAIGHT LINE WINDS.
00:05 UTCTSTM WND DMGWheatlandHickory, MOSEVERAL LARGE TREES BLOWN DOWN AND MINOR STRUCTURAL DAMAGE TO ROOF TO CITY HALL. LARGE TREE FELL ON A HOUSE. WINDOWS BLOWN OUT TO AREA CAFE.
00:20 UTCTSTM WND DMG1 S WarsawBenton, MOPICTURE FROM SOCIAL MEDIA SHOWED A LARGE TREE BLOWN DOWN NEAR WARSAW. TIME WAS ESTIMATED BY RADAR.
01:04 UTCTSTM WND DMGBranchCamden, MODAMAGE TO SIDING AND SHINGLES TO A COUPLE HOTELS NEAR WHITE WATER PARK.

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

This ground now

The live radar over the trackEvery 2013 tornado in MissouriEvery tornado in Missouri since 1950Warnings in force in Missouri nowThe forecast where you are

The other tornadoes of May 20, 2013

35 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 202:56 PM CDTEF5Moore tornado, OK13.81,90024212$2.0 billion
May 202:58 PM CDTEF0Stephens, OK1.030
May 203:07 PM CDTEF1Stephens, OK4.0200$20,000
May 203:51 PM CDTEF1Washington, OK6.5500$5,000
May 204:12 PM CDTEF0Montgomery, KS0.550
May 204:21 PM CDTEF1Washington, OK4.5400$10,000
May 204:33 PM CDTEF1Washington, OK6.0500$30,000
May 204:35 PM CDTEF0Brown, TX1.250
May 204:40 PM CDTEF0Lincoln, OK1.2100
May 204:50 PM CDTEF0Stanton, KS0.450
May 204:57 PM CDTEF1Pettis, MO14.5200$20,000
May 205:05 PM CDTEF0Stanton, KS0.350
May 205:37 PM CDTEF0Cedar, MO3.2100$50,000
May 205:41 PM CDTEF0Montague, TX0.950
May 205:41 PM CDTEF1Brown, TX3.6350$100,000
May 204:53 PM MDTEF0Alamosa, CO0.175
May 206:00 PM CDTEF0Brown, TX0.250
May 206:03 PM CDTEF1Barton, MO6.8100$50,000
May 206:25 PM CDTEF2Ottawa, OK10.0800$1.0 million
May 206:32 PM CDTEF1Adair, OK to MO2.0150
May 206:32 PM CDTEF1Ottawa, OK to MO9.3600$250,000
May 206:35 PM CDTEF1Adair, OK2.5300$15,000
May 206:40 PM CDTEF1Adair, OK to AR8.0500$225,000
May 206:49 PM CDTEF1Benton, AR2.9500$50,000
May 206:49 PM CDTEF1Coal, OK5.9250$30,000
May 207:24 PM CDTEF1Benton, AR0.8270$50,000
May 207:24 PM CDTEF1Marion, MO1.250
May 207:25 PM CDTEF0Mills, TX1.1100
May 207:50 PM CDTEF1Stone, MO1.4200$50,000
May 208:05 PM CDTEF0Stone, MO0.6100
May 208:05 PM CDTEF1Stone, MO1.4100
May 208:33 PM CDTEF0LeFlore, OK0.7260
May 208:44 PM CDTEF1LeFlore, OK8.5500$5,000
May 208:46 PM CDTEF0Morgan, MO0.7100$50,000
May 2010:14 PM CDTEF2Macoupin, IL0.2753

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.