EF1 tornado, Murdock to Sunburg, Minnesota, September 19, 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

September 19, 2017

Touchdown

12:28 AM CDT (05:28 UTC)

Lifted

12:39 AM CDT (05:39 UTC)

On the ground

11 minutes

Path length

12.6 miles (20.3 km)

Path width

550 yards (503 m)

Deaths

0

Injuries

0

Property damage

$1.6 million

Counties

Swift and Kandiyohi counties

Touchdown point

45.255, -95.423

Lift-off point

45.373, -95.225

Record number

1709192328-01

61 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 97 mph.

• downburst hit town. no evidence of any direction other than sw to ne. Numerous other trees down in the centraland southern part of Belgrade; all due to downburst.
• Several trees were down toward the ese.
• Large branches were downed to the southeast.
• tin strewn. broken trees to West of data point. looking nnw at shed. corn flattened in spots.

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

A strong and potent upper level disturbance, combined with a cold front sweeping across the eastern Dakotas, fired a line of severe thunderstorms that moved eastward into western Minnesota toward midnight. This line of storms continued to progress east-northeast across southern and central Minnesota, which produced fast-moving tornadoes, severe measured wind gusts, and hail as large as tennis balls. This line slowly weakened as it moved into far eastern Minnesota, with general, non-severe thunderstorms as the line progressed into west central Wisconsin after 3 am.

A tornado touched down in a corn field northwest of Murdock and moved northeast. The first structure that was hit was a church, which lost part of its roof. Along the way, the tornado destroyed corn fields, knocked down or broke many trees, and blew apart six empty grain bins that were ready for harvest. Three machine or equipment storage sheds were also destroyed and the roof of a restaurant was partially torn off. The tornado then moved into Kandiyohi County (see separate entry).

A tornado touched down southwest of Camp Lake, where it hit some trees at a farmstead. It then moved across fields, damaging or destroying corn fields. It partially tore the roof off a turkey barn before hitting homes along the east side of Camp Lake. It was here that an observer reported his flag was blowing hard from the northwest as tennis ball size hail hit, then the flag suddenly switched and was blowing from the southeast while the hail continued, then from the southwest when the tornado moved in. One modular home had windows blown in, a porch blown away, and its roof was uplifted to the point where driving rain got into much of the house. The tornado then hit an abandoned farm, rolling a mobile home and destroying several outbuildings before moving into Pope County (see separate entry).

A tornado moved out of Swift County and into northwestern Kandiyohi County. It knocked down trees, damaged crops, and destroyed two machine sheds at a farm.

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 severe thunderstorm watch, issued at 03:36 UTC and running to 06:24 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 01:00 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.

Benson Municipal (BBB), 26 km from the path, in the two hours either side.

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

The Minneapolis radar (KMPX), 147 km away, was scanning. The volume nearest the touchdown began at 05:25 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

11 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.