Tornadoes · United States · Iowa · 2015

EF0 tornado, Swedesburg, Iowa, July 16, 2015

This EF0 tornado ran 1.5 miles across Henry County on July 16, 2015, touching down at 5:14 PM CDT and reaching 10 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
July 16, 2015
Touchdown
5:14 PM CDT (22:14 UTC)
Lifted
5:15 PM CDT (22:15 UTC)
On the ground
1 minutes
Path length
1.5 miles (2.4 km)
Path width
10 yards (9 m)
Deaths
0
Injuries
0
County
Henry County
Touchdown point
41.083, -91.579
Lift-off point
41.088, -91.551
Record number
1507161614-01

What the Weather Service recorded

A wave on a northward moving warm front produced scattered thunderstorms along the boundary. Low level wind shear was favorable for severe weather and tornadoes.

An EF0 tornado with maximum winds estimated at 80 mph touched down 1.9 miles southwest of Swedesburg, IA. It traveled 1.51 miles and lifted 0.8 miles south of Swedesburg. The average path width was 10 yards. No damage was reported.

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 severe thunderstorm watch, issued at 21:58 UTC and running to 02:11 UTC.

Issued (UTC)ExpiredProductOffice
09:00 UTC06:00 UTCFlash Flood WatchDVN
21:58 UTC02:11 UTCSevere Thunderstorm WatchDVN
22:13 UTC22:45 UTCSevere Thunderstorm WarningDVN

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.

Davenport, (KDVN), 12:00Z

10.2 hours before the tornado, 107 km from the path. July 16, 2015.

Skew-T log-pSkew-T log-p diagram, Davenport, at 12:00Z on 2015-07-16Temperature 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 -54138, lifted condensation level 1260 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 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, Davenport, at 12:00Z on 2015-07-16The 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 44 square meters per square second, 0 to 6 km bulk shear 17 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
0 J/kg
Mixed-layer CIN
-54138 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1260 m above ground
0-6 km bulk shear
17 kt
0-1 km bulk shear
11 kt
0-1 km storm-relative helicity
44 m²/s²
0-3 km storm-relative helicity
229 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.5 K/km

Open this sounding in Storm Lab

Davenport, (KDVN), 00:00Z

1.8 hours after it, 107 km from the path. July 17, 2015.

Skew-T log-pSkew-T log-p diagram, Davenport, at 00:00Z on 2015-07-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 883 joules per kilogram, CIN -30, lifted condensation level 796 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 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, Davenport, at 00:00Z on 2015-07-17The 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 141 square meters per square second, 0 to 6 km bulk shear 24 knots.1939Sfc1 km3 km6 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
883 J/kg
Mixed-layer CIN
-30 J/kg
Surface CAPE
1247 J/kg
Mixed-layer LCL
796 m above ground
0-6 km bulk shear
24 kt
0-1 km bulk shear
22 kt
0-1 km storm-relative helicity
141 m²/s²
0-3 km storm-relative helicity
181 m²/s²
Significant tornado parameter
0.5
Supercell composite
3.0
0-3 km lapse rate
5.4 K/km

Open this sounding in Storm Lab

The surface observations

Mount Pleasant (MPZ), 16 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
20:15 UTC82.472.5150° 8 kt1009.5
20:25 UTC83.373150° 9 kt1009.1
20:35 UTC8473160° 10 kt1009.1
20:45 UTC84.5673.22160° 8 kt1009.1
20:55 UTC85.6473.58160° 8 kt141009.1
21:05 UTC86.1873.76170° 8 kt1008.8
21:15 UTC85.2873.4150° 11 kt1008.8
21:25 UTC85.2873.4170° 11 kt1008.5
21:35 UTC8573160° 11 kt1008.1
21:45 UTC84.3873.4160° 10 kt1007.5RA
21:55 UTC8473.76160° 9 kt1007.5-RA
22:05 UTC84.274.12150° 9 kt1007.5-RA
22:15 UTC84.3874.3150° 8 kt1007.5
22:25 UTC84.3874.66180° 8 kt1007.5
22:35 UTC84.5674.84200° 5 kt1007.1
22:45 UTC84.3875.2200° 5 kt1006.8
22:55 UTC84.275.2160° 6 kt1006.8
23:00 UTC8475.2170° 5 kt1006.8-RA
23:10 UTC83.4875.2270° 4 kt1006.8
23:25 UTC82.5869.8210° 16 kt311007.5-RA
23:35 UTC80.4269.26220° 7 kt1007.1
23:45 UTC79.771240° 6 kt1007.1
23:55 UTC79.771.78230° 6 kt1007.1
00:00 UTC79.772230° 4 kt1007.5

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

The radar

The Quad Cities radar (KDVN), 101 km away, was scanning. The volume nearest the touchdown began at 22:12 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
21:07 UTCHEAVY RAIN 1.55 E CantrilVan Buren, IA24 HOUR RAINFALL
22:07 UTCTORNADO 03 E TrentonHenry, IARATING EF-0. ESTIMATED PEAK WIND 75 MPH. PATH LENGTH 1.9 MILES. MAX WIDTH 25 YARDS. START TIME 507 PM CDT. START LOCATION 2.8 MILES E TRENTON IA. END TIME 512 PM CDT. END LOCATION 2.1 MILES S SWEDESBURG IA.
22:15 UTCTORNADO 03 E TrentonHenry, IARATING EF-0. ESTIMATED PEAK WIND 75 MPH. PATH LENGTH 1.9 MILES. MAX WIDTH 25 YARDS. START TIME 514 PM CDT. START LOCATION 2.8 MILES E TRENTON IA. END TIME 515 PM CDT. END LOCATION 2.1 MILES S SWEDESBURG IA.
22:18 UTCFUNNEL CLOUDOldsHenry, IA
22:44 UTCHAIL 2.751 N BurlingtonDes Moines, IAVIA SOCIAL MEDIA
22:45 UTCHAIL 1.752 Wnw BurlingtonDes Moines, IA
22:49 UTCFUNNEL CLOUDW BurlingtonDes Moines, IASTARTING TO DISSIPATE...NOT TOUCHING THE GROUND.
22:55 UTCTORNADOBurlingtonDes Moines, IAPOSSIBLE TORNADO OVER BURLINGTON MOVING TOWARD GULFPORT
22:57 UTCFUNNEL CLOUD1 S BurlingtonDes Moines, IA2 FUNNEL CLOUDS. OVER HILLSIDE DISTRICT THE OTHER SOUTH OF BURLINGTON MOVING TOWARD THE RIVER.

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

This ground now

The live radar over the trackEvery 2015 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

The other tornadoes of July 16, 2015

8 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 166:09 PM CDTEF1Henderson, IL0.8100$25,000
July 166:49 PM CDTEF1Warren, IL1.450$2,000
July 167:00 PM CDTEF1Rock Island, IL1.1200$2,000
July 167:09 PM CDTEF2Warren, IL1.7300$150,000
July 167:13 PM CDTEF2Warren, IL6.07001$1.5 million
July 168:34 PM CDTEF0Mitchell, IA2.140$40,000
July 168:48 PM CDTEF0Whiteside, IL0.610
July 1611:39 PM CDTEF2Tazewell, IL2.42501$1.2 million

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.