EF2 tornado, Central City to Monticello Muni Arpt, Iowa, June 28, 2017

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.

Rating

EF2

Date

June 28, 2017

Touchdown

6:38 PM CDT (23:38 UTC)

Lifted

7:01 PM CDT (00:01 UTC)

On the ground

23 minutes

Path length

11.7 miles (18.8 km)

Path width

200 yards (183 m)

Deaths

0

Injuries

1

Counties

Linn and Jones counties

Touchdown point

42.192, -91.527

Lift-off point

42.287, -91.341

Record number

1706281738-01

4 damage points were recorded along this path by NWS DVN, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 107 mph.

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

Low pressure moving along a cold front helped produce supercell thunderstorms with large hail, damaging winds, and tornadoes over much of Iowa the afternoon and evening of June 28th, 2017. This event produced two EF2 tornadoes between Cedar Rapids and Dubuque, Iowa, and a few other weak tornadoes in eastern Iowa.

The tornado touched down south of Central City in the county fairgrounds outfield area, and tracked about 12 miles northeast through Prairieburg before lifting in rural Jones County. The most intense damage occurred near and in Prairieburg. At a farmstead just southwest of town, a woman was injured when her garage collapsed on her. In Prairieburg, the grain elevator sustained severe damage, one mobile home was lofted and destroyed, and another mobile home severely damaged. On the east edge of town, a horse barn was destroyed. One horse was killed and two others sustained injuries. Northeast of town, a hog building was destroyed, killing several young hogs. This EF2 tornado continued into Jones County, Iowa.

The tornado touched down south of Central City in the county fairgrounds outfield area, and tracked about 12 miles northeast through Prairieburg before lifting in rural Jones County. The most intense damage occurred near and in Prairieburg. At a farmstead just southwest of town, a woman was injured when her garage collapsed on her. In Prairieburg, the grain elevator sustained severe damage, one mobile home was lofted and destroyed, and another mobile home severely damaged. On the east edge of town, a horse barn was destroyed. One horse was killed and two others sustained injuries. Northeast of town, a hog building was destroyed, killing several young hogs. This EF2 tornado moved in from Linn County.

A narrow EF2 tornado with winds estimated at 120 mph touched down in a field about 4 miles north of Monticello and tracked east northeast from Jones County crossing into Delaware County. The tornado struck neighboring farmsteads at the junction of 148th Ave. and Jones-Delaware County Road. Two grain bins and seven outbuildings were destroyed. Two garages had the doors blown in and five wooden power poles were snapped, including three larger transmission lines. The most unusual damage was an 18 foot missile that was formed from four sections of a grain bin roof that were folded into a narrow cone shape and propelled into the garage attic over 100 yards away. This EF2 tornado began in Jones County, and moved into Delaware County.

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

2 minutes of warning. NWS DVN issued a tornado warning for this county at 23:36 UTC, 2 minutes before the tornado touched down, in force until 00:15 UTC.

The county was under a tornado watch, issued at 19:55 UTC and running to 03:00 UTC.

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 Storm Prediction Center had this point in a Enhanced Risk, with a 0.05 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 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.

Monticello Municipal (MXO), 23 km from the path, in the two hours either side.

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

The Quad Cities radar (KDVN), 99 km away, was scanning. The volume nearest the touchdown began at 23:35 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.

Local storm reports within 60 km of the path, in the three hours either side.

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

The live radar over the trackEvery 2017 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

25 more were confirmed in the United States that day.

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.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.