F0 tornado, Toledo, Iowa, April 13, 2006

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

April 13, 2006

Touchdown

7:10 PM CDT (00:10 UTC)

Path length

0.1 miles (0.2 km)

Path width

30 yards (27 m)

Deaths

0

Injuries

0

County

Tama County

Touchdown point

42.050, -92.520

Lift-off point

42.050, -92.520

Record number

351

An unseasonably warm airmass overspread Iowa during the day on the 13th. Maximum temperatures reached the mid 80s to low 90s across the state. Dew point readings were in the upper 50s to low 60s. A weak frontal boundary extending north-northeast to south-southwest advanced into the state during the late afternoon. The airmass had become very unstable with Lifted Indices in the -5 to -8 range. CAPE values reached 3500 by the late afternoon hours. Thunderstorms erupted late in the afternoon and became severe very quickly. The main mode of severe weather with the storms was large hail. The freezing level was around 12,300 feet. Though quite high for mid April, it was easily low enough to make hail production easy. Several of the storms exhibited the structure of a tornadic supercell. The LCL was quite high however, at around 7300 feet. This limited the development of tornadoes somewhat. One tornado touched down in Tama County, northeast of Toledo. The tornado was on the ground briefly and touched down in an open field. No damage was reported with the tornado. Many of the storms produced large hail. There were numerous reports of one to two inch diameter hail. A couple of the storms produced very large hail. Hail of tennis ball to base ball size was reported in Hardin County south of Radcliffe and southwest of Hubbard. The same storm that produced the brief tornado touchdown in Tama County also produced hail of two and one half inches in diameter east of the Traer area.

Tornado touched down briefly in open fields northeast of Tama. No damage occurred.

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

12 minutes of warning. NWS DMX issued a tornado warning for this county at 23:58 UTC, 12 minutes before the tornado touched down, in force until 00:29 UTC.

The county was under a severe thunderstorm watch, issued at 23:00 UTC and running to 02:48 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, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:58 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), 106 km away, was scanning. The volume nearest the touchdown began at 00:08 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 2006 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

17 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.