EF0 tornado, Buffalo Center, Iowa, June 1, 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 1, 2014

Touchdown

12:42 PM CDT (17:42 UTC)

Lifted

12:44 PM CDT (17:44 UTC)

On the ground

2 minutes

Path length

1.1 miles (1.7 km)

Path width

25 yards (23 m)

Deaths

0

Injuries

0

County

Winnebago County

Touchdown point

43.373, -93.931

Lift-off point

43.372, -93.909

Record number

1406011142-01

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.

• Twitter screen capture of a photo of the tornado. Video also taken at the same time confirms that this circulation was connected to cloud base.

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

A warm and humid airmass was in place over Iowa during the day on the 1st. Maximum temperatures were in the 80s to near 90, with dew points in the mid 60s to around 70. The atmosphere became unstable with CAPE values around 2000 J/kg. Downdraft CAPE was between 900 and 1200 J/kg. The freezing level was quite high, around 14,000 feet with CAPE in the -10 to -30 C layer of the atmosphere around 500 J/kg. Precipitable water values were between 1.3 and 1.6 inches. The LCL in northern Iowa was around 1000 meters. A line of thunderstorms formed along the front by afternoon and propagated into Iowa. The storms produced a weak landspout in Winnebago County west of Buffalo Center. The storms produced little in the way of large hail with the largest report receiving being of nickel size hail in Calhoun County at Manson. Most storms produced wind gusts of 35 to 55 MPH. Very heavy rainfall occurred over northwest Iowa with reports of 4 to 6 inches in Kossuth and Palo Alto Counties in a few hours. The heaviest rainfall was a 6 inch report northeast of Cylinder in Palo Alto County. There was also 5.28 inches measured in Kossuth County south of Lone Rock by a mesonet station. The heavy rains resulted in Flash Flooding in Kossuth County.

A brief landspout occurred to the southeast of Buffalo Center on leading edge of storm.

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. One was issued for the county at another hour that day.

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 16:32 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 Minneapolis radar (KMPX), 167 km away, was scanning. The volume nearest the touchdown began at 17:43 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

4 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.