EF2 tornado, Genoa to Udell, Iowa, March 6, 2017

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 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mphthis tornado

   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

EF2

Date

March 6, 2017

Touchdown

8:16 PM CST (02:16 UTC)

Lifted

8:29 PM CST (02:29 UTC)

On the ground

13 minutes

Path length

14.9 miles (24.0 km)

Path width

250 yards (229 m)

Deaths

0

Injuries

0

Property damage

$2.0 million

Counties

Wayne and Appanoose counties

Touchdown point

40.617, -93.209

Lift-off point

40.749, -92.983

Record number

1703062016-01

29 damage points were recorded along this path by NWS DMX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF2. The highest wind the damage implies is 124 mph.

• Garage add on structural lost

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

A low pressure system developed off the Rockies in the Wyoming, Nebraska, South Dakota region and deepened as it moved eastward through South Dakota through the day on the March 6th. Southerly flow had already established itself and was bringing up Gulf of Mexico moisture into the Plains. A dry line also developed out ahead of the parent cold front, sparking initial storms in eastern Nebraska during the afternoon hours. Storms relatively quickly developed into a linear system, though a few isolated storms developed out ahead of the main line and proceeded to produce severe hail. As the line of storms progressed eastward through Iowa, they produced numerous severe hail and damaging wind reports. Additionally, a few tornadoes developed along the line, producing damage primarily in central and southern Iowa.

NWS storm survey confirmed a tornado touched down about six miles southwest of Seymour in Wayne County where several trees sustained major damage and several farmsteads were damaged. The tornado then tracked northeast through rural sections of Wayne County and produced sporadic tree damage. The tornado then moved into the south side of Seymour and produced significant damage to |several homes and structures with the partial collapse of walls and roof structures and widespread tree damage. A brick school building also sustained major damage to its roof and walls. After doing additional damage to residences to the northeast of the school, it exited Seymour and crossed into Appanoose County.

Tornado crossed into Appanoose county from Wayne county. After crossing into Appanoose county, the tornado damaged a residence along 110th Avenue with several|trees being topped and buildings damaged. The tornado continued across mainly rural areas of western Appanoose county before crossing IA Highway 2 where minor|damage occurred to a farmstead. The tornado appeared to dissipate shortly after crossing Highway 2.

Tornado developed just east of Cincinnati and moved rapidly to the northeast. The tornado damaged many trees along its path as well as a few different outbuildings with top wind speeds of 90mph - of EF1 damage.

NWS storm survey confirmed a tornado touchdown on the south side of Centerville just after 830 pm. The tornado produced significant damage to a manufacturing facility with a partial collapse of walls and roof structures. The tornado tracked very quickly northeast damaging an outbuilding and taking a large section of a roof off a residence along Highway 2. Damage was also found to several outbuildings at a farmstead south of Udell with a camper being tipped on its side. The worst damage occurred near Centerville where damage was consistent with winds of 115 to 125 mph - or EF2 damage. Damage to the east was not quite as intense generally EF0 or EF1 damage. It should be noted that the tornado may not have been continuous along the the entire 10 mile path...as the damage appeared to be more intermittent.

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

20 minutes of warning. NWS DMX issued a tornado warning for this county at 01:56 UTC, 20 minutes before the tornado touched down, in force until 02:30 UTC.

The county was under a tornado watch, issued at 19:55 UTC and running to 02:59 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 Enhanced Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 00:54 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), 128 km away, was scanning. The volume nearest the touchdown began at 02:15 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 2017 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

53 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.