Tornadoes · United States · Iowa · 2014

EF0 tornado, Royal, Iowa, June 18, 2014

This EF0 tornado ran 0.2 miles across Clay County on June 18, 2014, touching down at 1:15 AM CDT and reaching 50 yards wide. It killed nobody, and did $5,000 of property damage.

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
June 18, 2014
Touchdown
1:15 AM CDT (06:15 UTC)
Lifted
1:16 AM CDT (06:16 UTC)
On the ground
1 minutes
Path length
0.2 miles (0.3 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
Property damage
$5,000
County
Clay County
Touchdown point
43.090, -95.330
Lift-off point
43.090, -95.326
Record number
1406180015-01

What the Weather Service recorded

Thunderstorms produced damaging winds and two brief tornadoes in Lyon, Clay, and Dickinson Counties in northwest Iowa from the late evening hours of June 17th to a little after midnight on June 18th.

A brief tornado damaged a few outbuildings.

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

The warnings

9 minutes of warning. NWS FSD issued a tornado warning for this county at 06:06 UTC, 9 minutes before the tornado touched down, in force until 06:30 UTC.

The county was under a tornado watch, issued at 04:41 UTC and running to 08:41 UTC.

Issued (UTC)ExpiredProductOffice
19:12 UTC03:00 UTCFlood WarningFSD
23:49 UTC04:41 UTCTornado WatchFSD
04:41 UTC08:41 UTCTornado WatchFSD
06:06 UTC06:30 UTCTornado WarningFSD
06:19 UTC06:48 UTCSevere Thunderstorm WarningFSD
06:26 UTC06:57 UTCTornado WarningFSD
18:01 UTC06:00 UTCFlood WarningFSD

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 06:10 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.

Omaha, NE (KOAX), 00:00Z

6.3 hours before the tornado, 215 km from the path. June 18, 2014.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2014-06-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 4092 joules per kilogram, CIN -70, lifted condensation level 1440 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, Omaha, NE at 00:00Z on 2014-06-18The 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 98 square meters per square second, 0 to 6 km bulk shear 28 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
4092 J/kg
Mixed-layer CIN
-70 J/kg
Surface CAPE
6297 J/kg
Mixed-layer LCL
1440 m above ground
0-6 km bulk shear
28 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
98 m²/s²
0-3 km storm-relative helicity
163 m²/s²
Significant tornado parameter
1.0
Supercell composite
14.4
0-3 km lapse rate
6.6 K/km

Open this sounding in Storm Lab

Omaha, NE (KOAX), 12:00Z

5.7 hours after it, 215 km from the path. June 18, 2014.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 2014-06-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 2189 joules per kilogram, CIN -404, lifted condensation level 1081 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, Omaha, NE at 12:00Z on 2014-06-18The 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 364 square meters per square second, 0 to 6 km bulk shear 25 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
2189 J/kg
Mixed-layer CIN
-404 J/kg
Surface CAPE
2884 J/kg
Mixed-layer LCL
1081 m above ground
0-6 km bulk shear
25 kt
0-1 km bulk shear
51 kt
0-1 km storm-relative helicity
364 m²/s²
0-3 km storm-relative helicity
327 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.2
0-3 km lapse rate
4.4 K/km

Open this sounding in Storm Lab

The radar

The Sioux Falls radar (KFSD), 126 km away, was scanning. The volume nearest the touchdown began at 06:14 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
04:27 UTCTORNADO5 S GeorgeLyon, IABRIEF TOUCHDOWN
06:08 UTCTSTM WND GST 593 Wnw SpencerClay, IA
06:13 UTCTSTM WND GST 663 Wnw SpencerClay, IA
06:15 UTCTORNADO3 Nw RoyalClay, IADAMAGE TO FARM OUTBUILDINGS
06:18 UTCTSTM WND DMGSpencerClay, IALARGE TREE LIMBS DOWN.
06:30 UTCTSTM WND DMGTerrilDickinson, IA6 TO 12 INCH LIMBS DOWN.
07:00 UTCTSTM WND DMGEmmetsburgPalo Alto, IATREES DOWN IN EMMETSBURG. TIME ESTIMATED

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

This ground now

The live radar over the trackEvery 2014 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

The other tornadoes of June 18, 2014

18 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
June 187:27 AM CDTEF0Dane, WI0.230
June 186:05 PM CDTEF1Hyde, SD0.740
June 186:07 PM CDTEF0Buffalo, SD2.0400
June 186:45 PM CDTEF0Buffalo, SD0.7250
June 186:58 PM CDTEF1Jerauld, SD0.750$15,000
June 187:00 PM CDTEF0Faulk, SD1.275
June 187:00 PM CDTEF0Hand, SD0.275
June 187:01 PM CDTEF1Jerauld, SD6.8150$50,000
June 187:08 PM CDTEF0McIntosh, ND0.020
June 187:08 PM CDTEF2Jerauld, SD0.8100$20,000
June 187:30 PM CDTEF2Jerauld, SD2.22001$5.2 million
June 187:43 PM CDTEF4Jerauld, SD11.58802$300,000
June 187:45 PM CDTEF2Jerauld, SD1.1100$25,000
June 188:49 PM EDTEF0Clarion, PA4.6150$25,000
June 188:16 PM MDTEF0Washington, CO0.150
June 188:26 PM MDTEF0Washington, CO0.150
June 188:36 PM MDTEF0Washington, CO0.150
June 1810:24 PM CDTEF0Lyon, MN0.350

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.