F1 tornado, Mt Ayr, Iowa, June 4, 2005

1. F040 to 72 mph

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

2. F173 to 112 mphthis tornado

   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

F1

Date

June 4, 2005

Touchdown

7:15 PM CDT (00:15 UTC)

Path length

1.0 miles (1.6 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Ringgold County

Touchdown point

40.620, -94.100

Lift-off point

40.570, -94.050

Record number

123

A very active pattern was in place over the central U.S. During the previous night, a strong short wave lifted northeast across the area, setting off a round of thunderstorms. The thunderstorms moved northeast of the area by afternoon with a large area of subsidence moving into Iowa. This allowed the atmosphere to recover during the afternoon. An upper level closed low pressure area was positioned over western and central Nebraska during the afternoon and evening hours. The low lifted northeast as a surface dry line extending south from the low advanced east across Kansas. The airmass was quite unstable with lifted indices around -8 C. by late afternoon and mixed layer CAPE values in the 3000 to 4000 J/kg range. The freezing level at the beginning of the event was around 14,000 feet. Thunderstorms became tornadic to the southwest of Iowa during the late afternoon. One of the storms produced a tornado in northern Missouri which crossed into Ringgold County. The tornado passed through farm fields for about a mile before lifting. Little damage resulted. The storms moved in to south central Iowa and produced some very large hail. Softball size hail fell during the early stages of the event in Ringgold County, with baseball size hail in Decatur County. As the system moved northeast, hail sizes decreased and the event turned into more of a wind event. There were several reports of 55 to 65 MPH winds received as the line lifted northeast. Some damage occurred, however the damage was not widespread.

Tornado crossed into Iowa from Harrision County, MO and passed across a few farm fields before lifting.

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

42 minutes of warning. NWS DMX issued a tornado warning for this county at 23:33 UTC, 42 minutes before the tornado touched down, in force until 00:30 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 0.25 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 20:03 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.

Lamoni (LWD), 15 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), 130 km away, was scanning. The volume nearest the touchdown began at 00:16 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.

The live radar over the trackEvery 2005 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

43 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.