EF1 tornado, Judson, Minnesota, July 9, 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 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

July 9, 2017

Touchdown

10:30 PM CDT (03:30 UTC)

Lifted

10:38 PM CDT (03:38 UTC)

On the ground

8 minutes

Path length

2.7 miles (4.3 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

Crop damage

$500,000

County

Blue Earth County

Touchdown point

44.172, -94.262

Lift-off point

44.166, -94.209

Record number

1707092130-01

20 damage points were recorded along this path by NWS MPX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 100 mph.

• insulation and debris northeast of barn that was damaged
• wood piece northeast of damaged barn
• roof torn off and lifted up, insulation blown northeast.
• corn leaning toward the southeast

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

There were two tornadoes and many reports of very large hail. ||Storms brought strong winds, heavy rain, hail and tornadoes to south central Minnesota, damaging buildings and crops in Blue Earth, Nicollet and Sibley Counties.||The July 9 tornadoes, thunderstorms and hail hit south central Minnesota hard, with softball-sized hail reported in the Sibley County towns of Gibbon and Winthrop. The National Weather Service confirmed two tornadoes, one which did severe damage to a Courtland farm site.||That large hail and major thunderstorm surfaced quickly near the McLeod-Sibley county line, then continued south toward the Iowa border. Crops in Blue Earth, Nicollet and Sibley counties sustained severe damage, with the Blue Earth County Sheriff���s Office reporting over 600 acres hit there.||Still, the worst hail damage seemed to focus in rural Nicollet County, where corn fields were stripped and soybeans badly damaged. The University of Minnesota Extension Service, which conducted a Thursday clinic for regional farmers at the United Farmers Cooperative headquarters in Winthrop, said corn has the ability to come back somewhat from the damage, but the soybean crop for some farmers might be gone.

The tornado knocked a chimney off, crushed two old barns and snapped an old spruce tree. It also caused damage to hundreds of acres of crops along County Road 20 and County Road 11, where the wind flattened much corn. Some stalks were snapped at the base.

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

11 minutes of warning. NWS MPX issued a tornado warning for this county at 03:19 UTC, 11 minutes before the tornado touched down, in force until 04:00 UTC.

The county was under a tornado watch, issued at 00:05 UTC and running to 07:00 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 00:47 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), 92 km away, was scanning. The volume nearest the touchdown began at 03:31 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 MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are

1 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.