EF0 tornado, Jewell, Iowa, July 6, 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

July 6, 2014

Touchdown

6:03 PM CDT (23:03 UTC)

Lifted

6:04 PM CDT (23:04 UTC)

On the ground

1 minutes

Path length

0.6 miles (0.9 km)

Path width

25 yards (23 m)

Deaths

0

Injuries

0

Crop damage

$1,000

County

Hamilton County

Touchdown point

42.324, -93.687

Lift-off point

42.319, -93.680

Record number

1407061703-01

1 damage points were recorded along this path by NWS DMX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0.

• Photo of the tornado behind the plant. Photo courtesy of the KCCI uLocal page.

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

A cold front moved through the state during the afternoon of the 6th. Temperatures warmed into the mid 80s to around 90, with dew points in the mid 70s to low 80s. The atmosphere became very unstable with CAPE rising to 8000 J/kg by late afternoon. Downdraft CAPE was around 1200 J/kg, with CAPE in the -10 to -30 C layer of the atmosphere between 800 and 1100 J/kg. The freezing level was high, around 15,000 feet with a 700 mb temperature around 12 C. Significant capping was in place. Precipitable water was between 1.6 and 1.8 inches with an LCL around 1000 meters. The lifted index fell to -13 C. There was a significant amount of CAPE in the 0-3 km layer of the atmosphere along the front, between 150 and 175 J/kg. Shear was quite weak however, with only 25 kts of effective shear available. The non-severe storm parameter was around 0.5 over northeast Iowa near the cold front. Eight tornadoes occurred during the evening. Fortunately, the tornadoes missed cities, though they did do considerable crop damage. There was little other severe weather reported with the storms. One inch diameter hail fell in Poweshiek County, while winds gusted to 60 MPH or more in Wapello County.

Brief landspout near Jewell stayed in rural agricultural fields.

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.

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. The outlook in force was issued at 19:27 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), 66 km away, was scanning. The volume nearest the touchdown began at 23:03 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

15 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.