F0 tornado, Glidden, Iowa, June 18, 2001

1. F040 to 72 mphthis tornado

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

2. F173 to 112 mph

   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

F0

Date

June 18, 2001

Touchdown

9:25 PM CDT (02:25 UTC)

Path length

0.2 miles (0.3 km)

Path width

30 yards (27 m)

Deaths

0

Injuries

0

County

Carroll County

Touchdown point

42.050, -94.730

Lift-off point

42.050, -94.730

Record number

164

A very unstable situation unfolded during the afternoon of the 18th into the evening hours. Very warm and fairly moist air was drawn north into Iowa as the warm front that had been to the south of the state the previous two days lifted north of Iowa during the day on the 18th. Dew point temperatures were in the low to mid 60s over much of Iowa. In spite of the relatively low dew points, the airmass became quite unstable. CAPE values were in the 3000 to 4500 J/kg range by the early evening. A cold front entered the state during the late afternoon hours. Thunderstorms developed explosively along the cold frontal boundary by early evening. A nearly solid like of thunderstorms began to move east across the state. One tornado was reported in Carroll County south of the Glidden area. The touchdown was brief and occurred in open country. Much of the severe weather with this event was in the form of hail. Numerous locations reported hail anywhere from three quarter inch in diameter up to golf ball size. The largest hail report was received from Emmet County. Baseball size hail fell south of the Armstrong area, causing considerable damage to roofs and crops in the area. As the evening progressed, the storms produced more winds, in part due to the collapse of the line. high winds caused scattered power outages around the state. A wind gust in Worth County moved a livestock trailer, pushing the trailer sideways. The line of thunderstorms weakened rapidly as the midnight hour approached.

Brief touchdown in open area south of town.

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

10 minutes of warning. NWS DMX issued a tornado warning for this county at 02:15 UTC, 10 minutes before the tornado touched down, in force until 02:45 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 00:51 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 Des Moines radar (KDMX), 91 km away, was scanning. The volume nearest the touchdown began at 02:23 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

5 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.