EF0 tornado, Osceola, Iowa, March 27, 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

March 27, 2014

Touchdown

4:41 PM CDT (21:41 UTC)

Lifted

4:43 PM CDT (21:43 UTC)

On the ground

2 minutes

Path length

0.7 miles (1.2 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

Property damage

$50,000

County

Clarke County

Touchdown point

40.985, -93.774

Lift-off point

40.995, -93.768

Record number

1403271541-01

6 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. The highest wind the damage implies is 79 mph.

• Loss of shingles and some exterior siding/gutters on a house. Garage door buckled. Photo taken by Allan Mathias, Clarke County EM.
• The tornado removed the sheet metel roof from the north side of a farm outbuilding. The rest of the roof structure was intact.
• A few shingles removed from the house roof.
• Top of pine tree snapped off.

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

Low pressure tracked from north central Kansas into central Iowa during the day on the 27th. This was the first spring type weather system of the season. Strong south winds ahead of the low drew moisture north into the state during the 26th into the 27th. The low level jet on the afternoon of the 27th was around 35 kts. The atmosphere became unstable with CAPE values rising to 500 to 1000 J/kg with shear of around 40 kts. Surface dewpoints rose to the low to mid 50s ahead of the low. The freezing level was only around 9000 feet. With available CAPE in the -10 to -30 layer of the atmosphere around 300 J/kg, many of the storms produced hail. Penny to nickel size hail was reported over south central Iowa. A brief tornado touchdown occurred about 3 miles south of Osceola.

Spotter about 1.5 miles north of the tornado saw small rope funnel which lasted only a couple of minutes. Initially encountered a house and tore a small section of roofing away. Also tipped over a parked semi-trailer scattering debris into the field across the road. Tornado proceeded northeast and tore the roof off an old farm machinery building on the west side of Highway 69 and then snapped one power pole in a farm field before dissipating.

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 General Thunderstorms Risk. The outlook in force was issued at 20:03 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.

Osceola (I75), 9 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The Des Moines radar (KDMX), 82 km away, was scanning. The volume nearest the touchdown began at 21:43 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

3 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.