Tornadoes · United States · Iowa · 2001

F0 tornado, Elberon, Iowa, April 8, 2001

This F0 tornado ran 0.1 miles across Tama County on April 8, 2001, touching down at 10:50 PM CDT and reaching 20 yards wide. It killed nobody.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  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.

The record

Rating
F0
Date
April 8, 2001
Touchdown
10:50 PM CDT (03:50 UTC)
Path length
0.1 miles (0.2 km)
Path width
20 yards (18 m)
Deaths
0
Injuries
0
County
Tama County
Touchdown point
42.020, -92.280
Lift-off point
42.020, -92.280
Record number
622

What the Weather Service recorded

Following the passage of the powerful storm system earlier in the weekend, another round of severe weather was on tap for the state. The cold front from the previous storm did not move all that far to the south of Iowa. As a result, warm and moist air was able to move north into Iowa rapidly. A warm front lifted into southern Iowa during the late afternoon hours, sending temperatures into the 80s over parts of southern Iowa. Dew point temperatures jumped into the low to mid 60s. The atmosphere became very unstable with thunderstorms developing along the front. Most of the storms were associated with the warm front itself, though a mesoscale feature moved along the front setting the stage for an additional like of thunderstorms that developed north to south in south central Iowa. The main feature with the storms was hail. There were numerous reports of hail ranging from nickel size up to golf ball size. Several of the storms had well developed meso circulations associated with them. A few tornadoes resulted. Two of the tornadoes were very small and only touched down briefly in Tama and Dallas Counties. The other tornadoes were stronger. One tornado touched down in Decatur County near Leon. Two people were injured, one requiring hospitalization, as a mobile home was overturned by the gust front ahead of the storm itself. The second of the stronger tornadoes moved through Adams County. A trailer house was overturned and the roofs were removed from two sheds on a farm northeast of Mt. Etna. Thunderstorms produced very heavy rainfall of one to two inches per hour over Ringgold County. Total rainfall approached 4 inches in less than 3 hours as storms repeatedly moved across the same areas. The rain caused flash flooding in the county. In one instance, Lotts Creek overtopped a road southeast of Mt. Ayr, causing nearly $50,000 in damage as the road washed out. As the storms moved through Decatur County, lightning stuck a house in Garde Grove. The house was set on fire, but it was not detected for several hours after the lightning strike. The house was destroyed and completely burned to the ground.

Brief touchdown.

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

The warnings

30 minutes of warning. NWS DVN issued a tornado warning for this county at 03:20 UTC, 30 minutes before the tornado touched down, in force until 04:00 UTC.

Issued (UTC)ExpiredProductOffice
02:30 UTC03:15 UTCSevere Thunderstorm WarningDVN
03:20 UTC04:00 UTCTornado WarningDVN

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 forecast that day

The Storm Prediction Center had this point in a Slight Risk. The outlook in force was issued at 00:47 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 air that afternoon

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.

Davenport, (KDVN), 00:00Z

3.8 hours before the tornado, 154 km from the path. April 9, 2001.

Skew-T log-pSkew-T log-p diagram, Davenport, at 00:00Z on 2001-04-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 455 joules per kilogram, CIN -16, lifted condensation level 1962 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Davenport, at 00:00Z on 2001-04-09The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 173 square meters per square second, 0 to 6 km bulk shear 51 knots.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
455 J/kg
Mixed-layer CIN
-16 J/kg
Surface CAPE
880 J/kg
Mixed-layer LCL
1962 m above ground
0-6 km bulk shear
51 kt
0-1 km bulk shear
18 kt
0-1 km storm-relative helicity
173 m²/s²
0-3 km storm-relative helicity
356 m²/s²
Significant tornado parameter
0.0
Supercell composite
4.2
0-3 km lapse rate
7.9 K/km

Open this sounding in Storm Lab

Davenport, (KDVN), 12:00Z

8.2 hours after it, 154 km from the path. April 9, 2001.

Skew-T log-pSkew-T log-p diagram, Davenport, at 12:00Z on 2001-04-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -84288, lifted condensation level 1342 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Davenport, at 12:00Z on 2001-04-09The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 192 square meters per square second, 0 to 6 km bulk shear 74 knots.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-84288 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1342 m above ground
0-6 km bulk shear
74 kt
0-1 km bulk shear
33 kt
0-1 km storm-relative helicity
192 m²/s²
0-3 km storm-relative helicity
174 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.2 K/km

Open this sounding in Storm Lab

The radar

The Des Moines radar (KDMX), 124 km away, was scanning. The volume nearest the touchdown began at 03:47 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.

This ground now

The live radar over the trackEvery 2001 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

The other tornadoes of April 8, 2001

5 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 88:57 PM CDTF0Nodaway, MO1.020
April 89:25 PM CDTF0Dallas, IA0.220
April 89:38 PM CDTF0Decatur, IA0.330$1,000
April 89:50 PM CDTF0Benton, IA0.110
April 810:49 PM CDTF1Adams, IA1.0501$100,000

What this means

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.

Sources

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.