EF1 tornado, Avery to Chillicothe, Iowa, June 20, 2015

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 mphthis tornado

   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

EF1

Date

June 20, 2015

Touchdown

6:09 PM CDT (23:09 UTC)

Lifted

6:14 PM CDT (23:14 UTC)

On the ground

5 minutes

Path length

3.6 miles (5.7 km)

Path width

175 yards (160 m)

Deaths

0

Injuries

0

Property damage

$80,000

Crop damage

$11,000

Counties

Monroe and Wapello counties

Touchdown point

41.118, -92.648

Lift-off point

41.091, -92.590

Record number

1506201709-01

21 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 115 mph.

• Roof gone, wall connection may have had some rot, hence lower bound.
• Crops flattened and pointing east into the circulation
• Inflow into tornado. Corn pointing SW into the tornado path.
• Road crossing. Snapped tree trunks to the northwest and southeast of here.

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

A low pressure system moved into the state during the day, dragging behind it a cold front that helped trigger off storms across portions of central and southern Iowa. Hail, damaging winds and a tornado occurred with the storms. The tornado moved from Monroe County into Wapello County damaging multiple farmsteads, power poles and a house.

Tornado started in far northeast Monroe county and moved southeast staying in rural areas but doing EF1 damage to a power line before exiting the county. This tornado moved into Wapello county.

This tornado moved from Monroe into Wapello county. This is the Wapello county portion. The circulation for this short-lived tornado originated on the northern flank of a small squall line bow segment. This circulation rapidly tightened south of Eddyville and broke off the line, where it became tornadic. Damage included multiple farmsteads that lost silos and outbuildings, bent power lines, snapped trees, and a house that lost its roof and east wall. Downburst damage also occurred upstream and downstream of the tornado track.

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.

The county was under a tornado watch, issued at 20:51 UTC and running to 01:16 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 20:00 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), 115 km away, was scanning. The volume nearest the touchdown began at 23:10 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 2015 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

10 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.