EF1 tornado, Liberty Center to Pleasantville, Iowa, June 5, 2008

1. EF065 to 85 mph

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

2. EF186 to 110 mphthis tornado

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

3. EF2111 to 135 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. EF3136 to 165 mph

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

5. EF4166 to 200 mph

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

6. EF5over 200 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

EF1

Date

June 5, 2008

Touchdown

12:10 AM CDT (05:10 UTC)

Lifted

12:28 AM CDT (05:28 UTC)

On the ground

18 minutes

Path length

18.3 miles (29.4 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

0

Property damage

$180,000

Crop damage

$10,000

Counties

Warren and Marion counties

Touchdown point

41.220, -93.528

Lift-off point

41.420, -93.310

Record number

0806052310-01

A very dynamic weather situation unfolded during the 5th into the 6th. Although the atmosphere was summer like in the lower elevations, the upper levels were more typical of April. A strong upper level low pressure area lifted northeast out of the southern Rockies with a negatively tilted trough of low pressure lifting northeast across the central U.S. An intense low pressure area developed over northern Kansas and lifted north into southeast North Dakota by the morning of the 6th, with a central Pressure of 984 mb. During the day on the 5th, the atmosphere was capped with the freezing level rising to 15,600 feet by the evening hours over central Iowa. A warm front lifted north across Iowa, with temperatures warming into the mid 80s to the south of the front with dewpoint readings in the low 70s. It became quite unstable by evening with MUCAPE between 2500 and 3000 J/kg and lifted indices in the -5 to -9 C. range. Considerable shear was available with the effective shear between 40 and 65 kts by evening. Downdraft CAPE was between 800 and 1400 J/kg across the CWA, with 400 to 500 J/kg of CAPE available in the -10 to -30 C. layer of the atmosphere. The airmass became very moist by evening with 1.6 to 1.9 inches of precipitable water available by evening. The LCL fall to between 750 and 1250 meters. Thunderstorms erupted to the southwest of Iowa in central Kansas, along the dry line there. The storms raced northeast into Iowa by sunset. In spite of the dynamics that were in place, the amount of severe weather was relatively limited. Hail was limited by the high freezing level and lack of supercellular development. Several of the storms produced small hail and a few produced high winds. There were several reports of brief tornado touchdowns, but little in the way of damage was reported for the most part. The first tornado touched down in Cass County and was only on the ground briefly. Another tornado touched down in Union County. The tornado took the roof off of an outbuilding and knocked down some power lines. The strongest tornado was on the ground for over 18 miles in Warren and Marion Counties. The tornado track was over open country for the most part and damaged outbuildings and one house. Three other tornadoes touched down in Jasper County, causing some moderate damage. The most significant feature with this event was the flash flooding. Soil conditions across the state were very saturated. Any significant rainfall resulted in flash flooding. A narrow band of heavier rainfall stretched from south central into central Iowa. Flash flooding occurred in the Des Moines metro area as the airport recorded 4.15 inches of rainfall for the day, with about 3 inches falling in two hours. Reports of severe street flooding were received with numerous reports of manhole covers being blown off. During the event, high winds occurred over the far northwest part of the CWA as the surface low intensified rapidly and the gradient tightened. A window was blown out in Pocahontas County, with tree and power line damage done in Emmet County. A barn was also damaged near Gruver in Emmet County by the high wind.

Tornado touched down in the central part of the county and tracked to the northeast corner. For the most part, the track was across open country with damage to outbuildings and one house. Tornado crossed from Warren County in Marion County.

Tornado continued into Marion County from Warren County. Roof was taken off house.

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

8 minutes of warning. NWS DMX issued a tornado warning for this county at 05:02 UTC, 8 minutes before the tornado touched down, in force until 05:45 UTC.

The county was under a tornado watch, issued at 22:50 UTC and running to 06:00 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 High Risk, with a 0.15 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 00:53 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.

Knoxville (OXV), 26 km from the path, in the two hours either side.

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

The Des Moines radar (KDMX), 52 km away, was scanning. The volume nearest the touchdown began at 05:08 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 2008 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

40 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.