EF1 tornado, Winterset Arpt to Bevington, Iowa, June 30, 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

June 30, 2014

Touchdown

1:13 PM CDT (18:13 UTC)

Lifted

1:14 PM CDT (18:14 UTC)

On the ground

1 minutes

Path length

1.3 miles (2.2 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

Property damage

$10,000

Crop damage

$20,000

County

Madison County

Touchdown point

41.404, -93.953

Lift-off point

41.389, -93.937

Record number

1406301213-01

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

• 3 empty grain bins tipped.
• Also at this point...guttering 40 feet in top of other tree.
• House damage from tree impact. This tree was weakly rooted.
• Likely open south door. Square posts in ground with no concrete.

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

A very dynamic pattern was in place over the state with a closed low located over southern Canada into the north central U.S. A very strong jet of 85 to 100 kts as present at 250 mb. CAPE by early morning was already 3000 to 4000 J/kg with downdraft CAPE of 1000 to 1400 J/kg. CAPE in the -10 to -30 C layer of the atmosphere was between 1000 and 1400 J/kg. The freezing level was around 14,000 feet with precipitable water values near 2 inches. The LCL remained around 750 meters with 75 J/kg of CAPE in the 0-3 km layer. There was strong shear present, with 60-80 kts of effective shear. A cold front moved into Iowa during the day and moved across the state. This event was similar to the event of 29 June 1998. Thunderstorms formed over northeast Nebraska by sunrise and continued to propagate east into Iowa. The storms intensified as they moved across the state, into a forward moving MCS. As it strengthened into a Derecho, winds of 70 to 80 MPH were reported over a large swath of the state. All modes of severe weather occurred. Widespread wind damage was reported to trees, power lines, and structures from the high winds. In addition, very large hail occurred. Some of the larger hail included three to four inch diameter hail in Calhoun County near Rockwell City, and three and one half inch diameter hail in Warren County at Sandyville. Several tornadoes were confirmed. Very heavy rainfall occurred with the storms. The rain lead to flooding and flash flooding in many areas of northern and central Iowa. By the end of the month, a presidential disaster declaration had been made for the follow 9 Iowa counties: Adams, Clarke, Decatur, Mills, Montgomery, Pottawattamie, Ringgold, Taylor and Wayne. Governor Branstad also requested a disaster declaration for the following 26 Iowa Counties: Allamakee, Buchanan, Buena Vista, Butler, Cherokee, Chickasaw, Clay, Dickinson, Emmet, Fayette, Franklin, Hancock, Humboldt, Ida, Kossuth, Lyon, Osceola, Palo Alto, Plymouth, Pocahontas, Sac, Sioux, Winnebago, Winneshiek, Woodbury, and Wright. The Presidential declaration was granted on 24 July 2014.

A brief tornado touchdown with several trees damaged.

The tornado touched down NW of Patterson where an RFD surge was located and a curling motion noted in the damage patterns just upstream of the start point. The tornado proceeded to damage several small groves of trees over the next 1.9 miles. Here the tornado strengthened to EF1 where it snapped or uprooted several hundred trees. The path was often sporadic, owing likely to the hilly terrain of the area. The worst damage occurred to a home 2.5 miles NW of Bevington, which had the detached garage roof fail and take out part of the house roof as well. Roof and siding damage was noted to 5 homes.

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

29 minutes of warning. NWS DMX issued a tornado warning for this county at 17:44 UTC, 29 minutes before the tornado touched down, in force until 18:15 UTC.

The county was under a tornado watch, issued at 14:38 UTC and running to 22:53 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 Moderate Risk, with a 0.15 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 16:33 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 Des Moines radar (KDMX), 42 km away, was scanning. The volume nearest the touchdown began at 18:13 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

45 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.