F0 tornado, Boone, Iowa, July 26, 2000

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

July 26, 2000

Touchdown

3:15 PM CDT (20:15 UTC)

Path length

0.2 miles (0.3 km)

Path width

20 yards (18 m)

Deaths

0

Injuries

0

Property damage

$1,000

County

Boone County

Touchdown point

42.080, -93.920

Lift-off point

42.080, -93.920

Record number

974

After a brief break of about five hours, thunderstorms began to erupt in Iowa once again. As had been the case over the course of the previous several days to the north and west of Iowa, thunderstorms developed during the mid afternoon and became supercells within a short period of time. Wind profiles were favorable with a south to southeast flow in the low levels and a north to northwest flow in the mid and high levels. A cluster of thunderstorms developed over central and west central Iowa. Initially, the storms exhibited strong characteristics of being tornadic. There were a couple of tornado touchdowns during the first hour of the storms development. The first was northwest of Boone in Boone County. This tornado touched down in open country and was only on the ground for a short period of time. As the storms continued to develop, another tornado touched down in Guthrie County. This tornado was on the ground for a few miles before roping out and did cause some damage. Fortunately the tornado missed the city of Bagley. As the system progressed, the tornadic activity ended with the complex becoming a significant hail producer. Although there were some high winds reported with the storms, most of the winds were under 50 MPH. The hail from this complex did considerable crop damage as the entire complex tracked to the south-southwest. Most of the hail was in the one inch to one and three quarter inch range. Storms passing over Cass County produced baseball size hail near the town of Atlantic. The hail caused serious damage and even broke windows out of several houses. The other problem with the storms during this event was the extremely heavy rainfall. The airmass was very moist with deep moisture in place, even though the moisture ribbon was quiet narrow. Rainfall of one and one half inches was reported in Tama County in a 15 minute time period. This produced the first flash flooding of the afternoon. As the action shifted to the west, heavy rainfall occurred over Adair and Cass Counties. Rainfall of three to five inches was reported in both of these counties within a two hour period. Enough rain fell to cover a section of Interstate 80 to a depth of two to three feet with water in Adair County, forcing the closure of the Interstate for a period of time. Water was also over the interstate in Cass County north of Atlantic, resulting in a brief closure there as well. Meanwhile, the area of thunderstorms over central Iowa increased in strength. Heavy rainfall ensued over Tama County with an additional four inches of rainfall in a couple hour time period. Serious flooding was reported in Tama and Montour with water around three feet deep in the streets of both towns. The storms weakened over central and eastern Iowa during the early evening as they moved southeast. The storms over west central and southwest Iowa remained severe as they moved south-southwest out of the Des Moines County Warning Area.

Brief touchdown with minor tree damage

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. One was issued for the county at another hour that day.

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 21:13 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 live radar over the trackEvery 2000 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

4 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.