F0 tornado, Kamrar, Iowa, July 9, 2003

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 9, 2003

Touchdown

5:44 PM CDT (22:44 UTC)

Path length

0.2 miles (0.3 km)

Path width

25 yards (23 m)

Deaths

0

Injuries

0

County

Hamilton County

Touchdown point

42.370, -93.700

Lift-off point

42.370, -93.700

Record number

500

Unstable air remained in place over Iowa with the east west boundary remaining in place over Iowa. South of the boundary, the airmass became very unstable with temperatures in the upper 80s and dew point readings in the 75 to 80 degree range. It was much cooler to the north of the boundary with temperatures in the upper 60s and 70s. At the same time, a strong upper level disturbance dropped southeast toward Minnesota toward Iowa during the afternoon. Surface low pressure formed over Minnesota and along the cold front that extended southwest from the low. The storms became severe quickly as they advanced into Iowa. Winds were not a major factor in most cases with only a few gusts around 60 MPH reported. Scattered reports of hail were received as well with most of it around an inch in diameter. Golf ball size hail fell in Hardin County southwest of Buckeye. The same storm produced high winds that blew a corn crib down. One tornado occurred with these storms. A brief touchdown occurred in Hamilton County southeast of Kamrar. No significant damage was reported. A bit later in the evening, as upper level system approached from the northwest, strong thunderstorms developed over southern Minnesota. They entered Iowa during the mid evening hours, producing penny size hail and winds of up to 60 MPH.

Tornado touched down briefly in a field southeast of Kamrar.

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, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 20:07 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.

Webster City (EBS), 16 km from the path, in the two hours either side.

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

The live radar over the trackEvery 2003 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

20 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.