EF0 tornado, Montevideo, Minnesota, September 19, 2017

1. EF065 to 85 mphthis tornado

   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. 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

EF0

Date

September 19, 2017

Touchdown

12:18 AM CDT (05:18 UTC)

Lifted

12:20 AM CDT (05:20 UTC)

On the ground

2 minutes

Path length

2.1 miles (3.4 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

County

Chippewa County

Touchdown point

44.936, -95.735

Lift-off point

44.943, -95.693

Record number

1709192318-01

14 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 95 mph.

• Facing NE. Tree snapped ~10 ft of the ground, leaning to the east
• Facing south. Large tree ~2 ft in diameter twisted & snapped at base. Leaning to the east.
• Facing east. Trees snapped & falling south. Clear convergent damage
• Facing SE. Trunk snapped & leaning N. Clear conervegent damage

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.

This tornado began on the Chippewa County side of the Minnesota River, just east of the Montevideo golf course. It moved east-northeast across the south side of Montevideo. Most of the damage was to trees, but siding and shingles were taken off a few homes and the Montevideo Community Center.

This tornado uprooted or snapped dozens of trees south of Montevideo and just east of the Minnesota River.

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.

Montevideo (MVE), 3 km from the path, in the two hours either side.

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

The Minneapolis radar (KMPX), 170 km away, was scanning. The volume nearest the touchdown began at 05:19 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.