Unrated tornado, Dallas Center to Minburn, Iowa, September 9, 2019

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 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. Unratedthis tornado

   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

Unrated

Date

September 9, 2019

Touchdown

4:33 PM CDT (21:33 UTC)

Lifted

4:38 PM CDT (21:38 UTC)

On the ground

5 minutes

Path length

2.9 miles (4.6 km)

Path width

10 yards (9 m)

Deaths

0

Injuries

0

County

Dallas County

Touchdown point

41.754, -94.017

Lift-off point

41.791, -93.993

Record number

1909091533-01

A relatively cool, but juicy atmosphere existed across the area with southerly surface winds dominating and southwesterly mid and upper level flow. During the early morning hours of the 9th, scattered thunderstorms aided by the low level jet remained predominantly sub-severe with small hail. Through the morning and early afternoon hours, a surface warm front entered and moved across the state from southwest to northeast, all the while increasing MUCAPE values across the southeast half to two thirds of the state into the 2000-4000+ J/kg range. Additionally, moderate to steep low level lapse rates boosted DCAPE values into the 1000-1300 J/kg range, increasing the potential for strong downdrafts and resulting surface winds. Effective bulk shear was marginal through most of the event, yielding around 30 to 40kts. ||Resulting storms generally rolled through the state in waves from southwest to northeast, with at least periods of organization. The primary cluster of storms rolled through during the late afternoon, producing a fairly consistent trail severe thunderstorm winds and thunderstorm wind damage from southwest of Des Moines all the way through the Waterloo area. A second round of at least brief sever storms moved through overnight just southeast of the Des Moines metro, but was short lived unlike the cluster earlier in the day.

Small tornado moved through open cropland. No damage indicators were impacted, therefore the rating was EFU. Path was found using high resolution satellite imagery.

Tornado remained in open cropland east and northeast of Minburn. No damage indicators were impacted, therefore the EFU rating. The tornado path was discovered using high resolution satellite imagery.

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 20:33 UTC and running to 23:55 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 Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:58 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.

Perry (PRO), 15 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), 24 km away, was scanning. The volume nearest the touchdown began at 21:32 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 2019 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

6 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.