EF0 tornado, St Anthony to Union, Iowa, June 30, 2014

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.

Rating

EF0

Date

June 30, 2014

Touchdown

1:15 PM CDT (18:15 UTC)

Lifted

1:26 PM CDT (18:26 UTC)

On the ground

11 minutes

Path length

6.5 miles (10.5 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

0

Property damage

$52,000

Crop damage

$7,000

Counties

Marshall and Hardin counties

Touchdown point

42.171, -93.143

Lift-off point

42.221, -93.036

Record number

1406301215-01

127 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 110 mph.

• Wet ground...lowered wind. wind to trees in town...all straight line wind.
• another out building gone. trailer next to it was undamaged. more wwind
• Grain bins blown into fields to east.
• Continued narrow path at this point with slight roof damage to house. Tornado lifted shortly southeast of this area.

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.

This is a multiple segment tornado with three segments that passed through portions of Story, Marshall and Hardin counties. This is the second segment in Marshall county. After turning to the east and entering Marshall County, the tornado rapidly widened and intensified just after crossing County Highway S57. Severe damage occurred to a 500 yard wide stretch of trees along Minerva Creek along and north of 120th St. (part of the damage was likely attributable to RFD). The tornado continued east just north of 120th St. and completely destroyed a farm outbuilding, depositing the remnants of the building in the surrounding trees to the north and east. Very strong RFD winds caused widespread tree and building damage for over a mile south of the tornado path along this section of the track. Turning northeast, the tornado tracked across open farmland for the next 2.5 miles, grazing one farmstead in the process. The narrowing tornado directly hit a farmstead south of the 105th St. and Fariman Ave. intersection, with mostly low EF1 tree damage sustained. The tornado then continued into Hardin county.

This is a multiple segment tornado with two segments that passed through portions of Marshall and Hardin counties. This is the first segment in Marshall county. As the first tornado from this supercell began to occlude and pull NE, a second tornado appears to have formed a mile to the south and east. A path of more intense damage was noted on a survey that began just north of Marble Road between Eastman and Fredrick Ave. The tornado grazed three farmsteads, causing mostly tree and some outbuilding damage. As the tornado moved into an area with more trees around mile three of its path, convergent wind patterns were noted on the ground survey to the north and south of the track, with a 100-150 yard wide path through a line of trees along a creek east of U Ave. After crossing Ingram Ave, the tornado caused roof damage to at least one outbuilding. The tornado then moved in Hardin county.

This is a multiple segment tornado with three segments that passed through portions of Story, Marshall and Hardin counties. This is the third and final segment in Hardin county. The tornado cycled, made a hard right turn, and began to intensify again after crossing into Hardin County. EF1 damage was sustained to wooden power poles and trees along 335th St. between T and U Ave. Turning NE again after crossing U Ave, the tornado roamed through open farmland and weakened, only causing intermittent tree damage after crossing County Road S62 1.5 miles south of Union. The tornado dissipated shortly before reaching the Iowa River.

This was a multiple segment tornado with two segment including portions of Marshall and Hardin counties. This is the second and final segment in Hardin county. After crossing into Hardin county, the narrowing tornado left a highly convergent tree damage pattern across 335th St. The path washed out in a pasture NE of this point just west of the Iowa River.

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

19 minutes of warning. NWS DMX issued a tornado warning for this county at 17:56 UTC, 19 minutes before the tornado touched down, in force until 18:30 UTC.

The county was under a tornado watch, issued at 14:38 UTC and running to 21:28 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 0.10 chance of a tornado within 25 miles. 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), 74 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.