EF0 tornado, Creston Arpt, Iowa, June 4, 2008

1. EF065 to 85 mphthis tornado

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

2. EF186 to 110 mph

   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

EF0

Date

June 4, 2008

Touchdown

7:04 PM CDT (00:04 UTC)

Lifted

7:07 PM CDT (00:07 UTC)

On the ground

3 minutes

Path length

0.9 miles (1.4 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Union County

Touchdown point

41.027, -94.355

Lift-off point

41.028, -94.338

Record number

0806041804-01

A strong surge of very moist and unstable air moved into Iowa as a warm front stretched east to west along the Iowa/Missouri border. By the late afternoon hours, MUCAPE was in the 3000-4000 J/kg range with lifted indices between -5 and -8 C. Downdraft cape was between 800 and 1300 J/kg with an effective shear of 45 to 50 kts. Available CAPE in the -10 to -30 C. layer of the atmosphere was between 200 and 400 J/kg. Thunderstorms erupted by the evening and a cyclic supercell developed over southwest Iowa. By the time the night was done, three separate supercells took a similar track across southern Iowa. The LCL was quite low, between 500 and 1000 meters. Several tornado reports were received from Adams into Clarke Counties. The storms also produced winds of 60 to 70 MPH in places, with the strongest winds late in the event. A gust of 77 MPH was recorded in the Pella area. Winds northwest of Baxter flipped a propane tank. Hail was limited in size by the freezing level of 13,500 to 14,000 feet. The exception was during stronger periods of the supercell's life. At on point, golf ball to baseball size hail was reported in Union County. A cluster of thunderstorms formed over northern Iowa as well. Severe weather was isolated with this area of storms. Copious amounts of rain fell with the storms, both the supercells and the cluster across the north. Flooding became widespread with numerous reports of water over the roads along the track of the supercells, and also over parts of north central into northeast Iowa. The heaviest rainfall occurred over southwest Iowa, where northwest of Creston picked up nearly 8 inches of rain. Following the heavy rainfall of the previous night, Iowa Governor Chet Culver declared state disaster areas in both Union and Humboldt Counties. Seven tornado touchdowns occurred. Four of them were EF1 in strength and had path lengths ranging from 4 to 11 miles. Three of the tornadoes touched down in Adams County and four in Union County. The final tornado in Union County crossed into Clarke County shortly before dissipating.

Amateur radio operator reported a tornado just south of Creston.

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

26 minutes of warning. NWS DMX issued a tornado warning for this county at 23:38 UTC, 26 minutes before the tornado touched down, in force until 00:15 UTC.

The county was under a tornado watch, issued at 22:40 UTC and running to 04:56 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 0.10 chance of a tornado within 25 miles. The outlook in force was issued at 20:01 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), 94 km away, was scanning. The volume nearest the touchdown began at 00:02 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

45 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.