F1 tornado, Winthrop, Iowa, June 1, 2001

1. F040 to 72 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. F173 to 112 mphthis tornado

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. F2113 to 157 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. F3158 to 206 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. F4207 to 260 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. F5261 to 318 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

F1

Date

June 1, 2001

Touchdown

4:55 PM CDT (21:55 UTC)

Path length

1.0 miles (1.6 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

0

Property damage

$120,000

County

Buchanan County

Touchdown point

42.500, -91.770

Lift-off point

42.500, -91.730

Record number

993

Event Summary for 6/01/01:A vigorous upper level storm system and strong mid level jet moved through the Mid Mississippi Valley during the afternoon and evening. The associated surface cold front moved into East Central Iowa during peak heating. Mid level cooling and strong surface heating created a moderately unstable airmass. Speed and directional shear was also more than sufficient to spawn supercell thunderstorms near Waterloo, which moved east into Buchanan County producing several tornadoes. Eventually, the activity evolved into a squall line which moved across much of the remainder of Eastern Iowa, Northwest and West Central Illinois and Northeast Missouri. However, decreasing instability, coupled with the loss of daytime heating resulted in a gradual weakening of the storms and only a few severe reports. Here is a summary of the tornadoes which struck Buchanan and Delaware Counties:Buchanan County - 455 pm CDTAn F1 tornado touched down 2.5 miles north to northwest of Winthrop and lifted at 505 pm CDT approximately 2.25 miles north of Winthrop. This tornado was on the ground for about 1 mile and was 150 yards wide. This tornado produced the most severe damage from the entire event as it ripped through the Tempus farm site at 1846 Reed Avenue. The Tempus home suffered minor damage with a few windows blown out and pieces of siding removed. Several large outbuildings were totally destroyed, including a large machine shed, barn and an open faced cattle shed. Seven head of cattle were killed with 15 to 20 head of cattle injured. A large combine and several other pieces of farm equipment were damaged. Buchanan County - 501 pm CDTAn F0 tornado touched down 1 mile south of Fairbank near Baxter Avenue and 120th Street. This tornado produced no damage. A National Weather Service Cooperative Observer reported seeing this tornado as a white thin cloud touching the ground, but not appearing to connect with the cloud base. Hail also covered the ground about 4.7 miles south of Highway 281 on W13 and Amish Boulevard. Buchanan County - 506 pm CDTAn F0 tornado touched down one half mile southwest of Independence, just north of Highway 20 and west of Illinois Avenue. This was a brief touchdown with no damage. Buchanan County - 506 pm CDTAn F0 tornado touched down 1 mile west of Independence and lifted on the east end of town at approximately 516 pm. This tornado was on the ground for 3 miles and was 150 yards wide. This tornado produced mainly tree damage. A farm on the west side of Independence suffered minor damage to a grain elevator. Several homes in Independence also suffered minor damage, mainly to shingles and siding. Eyewitness reports indicated that a much broader rotation was associated with this tornado several hundred feet above the ground with possible multiple vortices. Buchanan County - 511 pm CDTAn F0 tornado touched down 2 miles southwest of Lamont near Taylor Avenue and 150th Street. This was a brief touchdown with no damage reported. Trained spotters observed this tornado as two smaller vortices, which merged together before lifting a short time later. Delaware County - 512 pm CDTAn F0 tornado touched down 2 miles northwest of Manchester. This was a brief touchdown with no damage reported. Buchanan County - 529 pm CDTAn F0 tornado touched down 3.5 miles southeast of Winthrop near County Road W45 and 260th Street. A hog confinement sustained minor damage and one older corn crib suffered damage. Evidence of this tornado was visible in a field approaching the damage site as old corn stock debris was swept into a nearby fence. Buchanan County - 534 pm CDTAn F0 tornado touched down 5.75 miles southeast of Winthrop near York Avenue and 280th Street. This was a brief touchdown with no damage reported.

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

20 minutes of warning. NWS DVN issued a tornado warning for this county at 21:35 UTC, 20 minutes before the tornado touched down, in force until 22:15 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. The outlook in force was issued at 20:47 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.

Oelwein (OLZ), 28 km from the path, in the two hours either side.

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

The Quad Cities radar (KDVN), 138 km away, was scanning. The volume nearest the touchdown began at 21:57 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.

The live radar over the trackEvery 2001 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

24 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.