Tornadoes · United States · Iowa · 2016

EF2 tornado, Vinton, Iowa, July 17, 2016

This EF2 tornado ran 1.6 miles across Benton County on July 17, 2016, touching down at 4:58 AM CDT and reaching 100 yards wide. It killed nobody and injured 5.

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 mphthis tornado

    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
EF2
Date
July 17, 2016
Touchdown
4:58 AM CDT (09:58 UTC)
Lifted
5:00 AM CDT (10:00 UTC)
On the ground
2 minutes
Path length
1.6 miles (2.6 km)
Path width
100 yards (91 m)
Deaths
0
Injuries
5
County
Benton County
Touchdown point
42.153, -92.033
Lift-off point
42.159, -92.002
Record number
1607170358-01

The damage survey

30 damage points were recorded along this path by NWS DVN, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF2. The highest wind the damage implies is 135 mph.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

What the Weather Service recorded

A nearly stationary frontal boundary spawned a line of thunderstorms that produced numerous reports of damaging winds and isolated tornadoes.

A tornado tracked across the southern parts of Vinton, with damage to over a dozen homes, an apartment complex and other buildings including some roofs removed. Numerous power poles and trees were down with damage to other structures like a cell phone tower and some corn fields.

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.

Issued (UTC)ExpiredProductOffice
09:37 UTC10:30 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 05:59 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), 00:00Z

10.0 hours before the tornado, 139 km from the path. July 17, 2016.

Skew-T log-pSkew-T log-p diagram, Davenport, at 00:00Z on 2016-07-17Temperature 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 -72488, lifted condensation level 1263 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 00:00Z on 2016-07-17The 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 71 square meters per square second, 0 to 6 km bulk shear 45 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
-72488 J/kg
Surface CAPE
197 J/kg
Mixed-layer LCL
1263 m above ground
0-6 km bulk shear
45 kt
0-1 km bulk shear
10 kt
0-1 km storm-relative helicity
71 m²/s²
0-3 km storm-relative helicity
182 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.1 K/km

Open this sounding in Storm Lab

Davenport, (KDVN), 12:00Z

2.0 hours after it, 139 km from the path. July 17, 2016.

Skew-T log-pSkew-T log-p diagram, Davenport, at 12:00Z on 2016-07-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 865 joules per kilogram, CIN -102, lifted condensation level 981 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, Davenport, at 12:00Z on 2016-07-17The 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 310 square meters per square second, 0 to 6 km bulk shear 52 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
865 J/kg
Mixed-layer CIN
-102 J/kg
Surface CAPE
540 J/kg
Mixed-layer LCL
981 m above ground
0-6 km bulk shear
52 kt
0-1 km bulk shear
39 kt
0-1 km storm-relative helicity
310 m²/s²
0-3 km storm-relative helicity
332 m²/s²
Significant tornado parameter
0.2
Supercell composite
2.3
0-3 km lapse rate
5.1 K/km

Open this sounding in Storm Lab

The radar

The Quad Cities radar (KDVN), 133 km away, was scanning. The volume nearest the touchdown began at 09:54 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
09:35 UTCTSTM WND DMG1 Nnw GilbertvilleBlack Hawk, IAA SHED AND A MORTON BUILDING PARTIALLY DESTROYED. NUMEROUS TREES AT LEAST 12 TO 18 INCHES IN DIAMETER SNAPPED NEAR THE BASE.
09:35 UTCTSTM WND DMG1 Sse Elk Run HeightsBlack Hawk, IANUMEROUS 2 TO 6 INCH DIAMETER TREE LIMBS DOWN IN RAYMAR. RELAYED BY KWWL. TIME ESTIMATED FROM RADAR.
09:49 UTCTSTM WND DMGJesupBuchanan, IAGRAIN BIN DESTROYED.
09:49 UTCTSTM WND DMGNw JesupBuchanan, IAGRAIN BIN DESTROYED AND BLOWN INTO ANOTHER STRUCTURE. THE GRAIN BIN WAS EMPTY
09:54 UTCTSTM WND DMGNe JesupBuchanan, IAGRAIN BIN DESTROYED WITH ANOTHER WITH THE SIDE PUSHED IN BY THE WIND.
09:55 UTCTSTM WND DMGS VintonBenton, IAROOF BLOWN OFF A LARGE APARTMENT BUILDING AND A HOUSE DAMAGED. TIME ESTIMATED FROM RADAR.
09:55 UTCTSTM WND GST 751 N IndependenceBuchanan, IAESTIMATED WINDS OF 70 TO 75 MPH BASED ON THE MOVEMENT OF THE TREES. NO DAMAGE WAS VISIBLE AT THE TIME OF THE REPORT.
10:10 UTCTSTM WND DMG2 E PaloLinn, IAREPORT WAS DELAYED....SPOTTER OBSERVED POWER FLAHES AROUND 510 AND THIS MORNING THERE WERE POWER LINES DOWN IN THE AREA WITH THE POWER OUT.
10:15 UTCTSTM WND GST 61W Cedar RapidsLinn, IAKCRG EQUIPMENT MEASUREMENT AT XAVIER HIGH SCHOOL ON THE WEST SIDE OF CEDAR RAPIDS. TIME OF THE EVENT IS ESTIMATED SINCE EXACT TIME IS UNKNOWN.
10:25 UTCTSTM WND DMG2 S ManchesterDelaware, IANUMEROUS TREE BRANCHES GREATER THAN 6 INCHES WERE OBSERVED DOWN IN THE AREA DURING A DAMAGE SURVEY. THESE TREES WERE DOWNED BY THE STORM ON 7/17. TIME IS BASED ON RADAR.
10:25 UTCTSTM WND GST 551 Sse Cedar RapidsLinn, IA50 TO 55 MPH GUSTS.
10:30 UTCHAIL 0.25SwisherJohnson, IA
10:46 UTCTSTM WND DMGWalfordBenton, IAMULTIPLE HOMES DAMAGE IN WALFORD WITH ONE COLLAPSED.

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

This ground now

The live radar over the trackEvery 2016 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

The other tornadoes of July 17, 2016

9 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 175:15 AM CDTEF2Benton, IA4.0754$275,000
July 176:03 AM CDTEF1Jackson, IA1.050$5.0 million
July 176:27 AM CDTEF0Scott, IA1.910
July 176:36 AM CDTEF1Scott, IA2.1100
July 178:30 AM CDTEF0Galveston, TX0.020
July 174:00 PM MDTEF0Bernalillo, NM0.05
July 178:18 PM CDTEF0Putnam, IL1.225
July 178:24 PM CDTEF0Putnam, IL0.225
July 179:41 PM CDTEF1Kankakee, IL2.2100

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.