EF1 tornado, Highland Center to Cosgrove, Iowa, April 27, 2014

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 mphthis tornado

   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.

Rating

EF1

Date

April 27, 2014

Touchdown

3:20 PM CDT (20:20 UTC)

Lifted

4:06 PM CDT (21:06 UTC)

On the ground

46 minutes

Path length

45.7 miles (73.5 km)

Path width

1,600 yards (1463 m)

Deaths

2

Injuries

0

Property damage

$25,000

Counties

Wapello, Keokuk, Iowa and Johnson counties

Touchdown point

41.133, -92.312

Lift-off point

41.660, -91.782

Record number

1404271420-01

41 damage points were recorded along this path by NWS DMX and NWS DVN, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 110 mph.

• Outbuilding completely destroyed.
• 3 poles broken into multiple pieces
• A mobile home, which had been tied down, was pushed to the north about 4 feet.
• A large wooden shed was pushed 3 feet to the north and suffered other minor damage.

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

A strong upper low moved into the central United States. Surface low pressure was located over northwest Kansas into southwest Nebraska during the late afternoon. A warm front extended from the low across northern Missouri into southern Illinois. A strong push of moisture took place south of the front with dewpoints rising into the upper 50s to low 60s. Precipitable water values increased to around 1.3 inches. The freezing level was relatively low, around 11,000 feet. The atmosphere was strongly sheared with 50 to 60 kts of shear available. By the afternoon, the atmosphere became unstable with 1000 to 2000 J.kg of CAPE available. Downdraft CAPE was quite high in the 700 to 1000 J/kg. CAPE in the -10 to -30 C layer of the atmosphere was around 200 J/kg. A strong line of thunderstorms formed on the east edge of the dry slot as it pushed into Iowa. Thunderstorms remained below severe levels through the morning, however, they intensified as the moved into south central and southeast Iowa. One tornado touched down in Wapello County before racing northward into Keokuk County. There were numerous reports of high winds as the line progressed east with winds of 60 to 70 MPH. Numerous trees were blown down by the high winds. The roof was taken off of a family medical center in northeast Oskaloosa in Mahaska County. Major structural damage was reported on a farmstead west of Ottumwa in Wapello County with outbuildings damaged and roof damage to the porch of the farmstead. Windows were blown out of cars and roofs were blown from buildings on a farmstead east of Cincinnati in Appanoose County. Ten people were injured, some requiring hospitalization, on the south side of Ottumwa. At least four of the ten were injured when thunderstorms winds lifted debris at an auction on the south side of the city. One injury was reported in Appanoose County when a woman was struck by debris lifted by strong winds. Lightning struck a car near Osceola in Clarke County. It struck the trunk of the car and set the trunk on fire.

A powerful storm system lifted into the central Plains on the afternoon of April 27, 2014 and brought several rounds of showers and thunderstorms to eastern Iowa. Some of these thunderstorms were severe and produced damaging winds and an isolated hail report. There was one confirmed tornado during the event that moved across Keokuk, Iowa and Johnson Counties with two fatalities. In addition to the damaging winds rainfall totals ranged from a half an inch to around 1 inch in a little under an hour.

Tornado formed initially as a broad circulation east of Highland Center. First damage was to a farm site where a chicken barn was destroyed and two power poles were snapped. As the tornado traveled quickly to the northeast and struck utility poles producing a considerable lean. The tornado then continued into Keokuk county.

NWS storm survey teams determined that a tornado developed in far northern Wapello County, crossed Keokuk County and southeastern Iowa County, and ended in rural southwest Johnson County. This entry is for the portion of the tornado that affected Keokuk County. ||This long track tornado started east of Highland Center and traveled at about 60 mph to the northeast. The circulation was initially very broad and began to tighten as it progressed to the northeast. The tornado moved into Keokuk County at around 323 pm CDT (223 pm CST). It then created a near-continuous damage path across Keokuk County, with damage primarily to outbuildings, trees, and power poles. In Martinsburg, a tied-down mobile home was also pushed to the north off its block base. Two fatalities occurred, one west of Martinsburg and on north of Kinross. Both fatalities were associated with people who were outdoors and caught in debris from outbuildings that were destroyed. ||The tornado was on the ground for about 30 miles across Keokuk County. It exited Keokuk County at about 352 pm and moved into Iowa County near the junction of the Keokuk-Iowa-Washington county lines.

NWS storm survey teams determined that a tornado developed in far northern Wapello County, crossed Keokuk County and southeastern Iowa County, and ended in rural southwest Johnson County. ||This entry is for the portion of the tornado that affected Iowa County. This long track tornado initially started east of Highland Center and traveled at about 60 mph to the northeast. After crossing Keokuk County, the tornado moved into Iowa County near the junction of the Iowa, Keokuk, and Washington County lines at around 352 pm CDT (252 pm CST). It left a damage path about 10 miles long in rural areas that included damage to outbuildings and trees. ||The tornado exited Iowa County at about 402 pm CDT (302 pm CST) and moved into Johnson County a few miles south of I-80.

NWS storm survey teams determined that a tornado developed in far northern Wapello County, crossed Keokuk County and southeastern Iowa County, and ended in rural southwest Johnson County. This entry is for the portion of the tornado that affected Johnson County. ||This long track tornado initially started east of Highland Center and traveled at about 60 mph to the northeast. After crossing Keokuk and southeastern Iowa Counties, the tornado moved into Johnson County about 10 miles southwest of Tiffin at around 4:02 pm CDT (3:02 pm CST). It left a path of scattered tree and shed damage for about 4.25 miles in rural southwest Johnson County as it weakened. ||It finally lifted about 4.2 miles south of Oxford at about 4:06 pm CDT (3:06 pm CST).

The deaths

2 direct deaths are recorded for this tornado, each with what Storm Data knows of it.

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

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 19:18 UTC and running to 21:43 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 Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 20:00 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.

The Quad Cities radar (KDVN), 124 km away, was scanning. The volume nearest the touchdown began at 20:21 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 2014 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

16 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.