Tornadoes · United States · Iowa · 1996

F1 tornado, Avery, Iowa, May 9, 1996

This F1 tornado ran 1.5 miles across Monroe County on May 9, 1996, touching down at 12:36 AM CDT and reaching 60 yards wide. It killed nobody and injured 2, and did $380,000 of property damage.

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 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.

The record

Rating
F1
Date
May 9, 1996
Touchdown
12:36 AM CDT (05:36 UTC)
Path length
1.5 miles (2.4 km)
Path width
60 yards (55 m)
Deaths
0
Injuries
2
Property damage
$380,000
County
Monroe County
Touchdown point
41.080, -92.750
Lift-off point
41.070, -92.730
Record number
167

What the Weather Service recorded

Strong thunderstorms fired as mentioned above in central Iowa. The main feature with the storms was the heavy rain. One of the storms became severe and produced a tornado near the town of Avery in Monroe County. It caused considerable damage. There were numerous reports of touchdown northeast of Albia. The tornado destroyed at least one trailer, several sheds, many large trees. It also damaged numerous houses, trailers, propane tanks, and fences. The tornado also damaged electrical wires cutting off electricity to most of the east half of the county, including Albia, for about 2 hours. There were two injuries reported with the tornado. They were relatively minor. A couple was in the trailer that was destroyed by the tornado. The wife was 8 months pregnant and gave birth the next day to a healty baby. It was fortunate that thought the trailer was destroyed, they both escaped with minor injuries. The actual path of the tornado was from a little northwest of Avery, tracking southeast for about 1 1/2 miles.

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

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

Issued (UTC)ExpiredProductOffice
18:25 UTC18:55 UTCSevere Thunderstorm WarningDMX

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 Moderate Risk. The outlook in force was issued at 05:48 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

5.6 hours before the tornado, 197 km from the path. May 10, 1996.

Skew-T log-pSkew-T log-p diagram, Davenport, at 00:00Z on 1996-05-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 552 joules per kilogram, CIN -63, lifted condensation level 696 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°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 1996-05-10The 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 -13 square meters per square second, 0 to 6 km bulk shear 42 knots.1939587897117136156175Sfc1 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
552 J/kg
Mixed-layer CIN
-63 J/kg
Surface CAPE
602 J/kg
Mixed-layer LCL
696 m above ground
0-6 km bulk shear
42 kt
0-1 km bulk shear
24 kt
0-1 km storm-relative helicity
-13 m²/s²
0-3 km storm-relative helicity
-495 m²/s²
Significant tornado parameter
-0.2
Supercell composite
-2.0
0-3 km lapse rate
5.7 K/km

Open this sounding in Storm Lab

Davenport, (KDVN), 12:00Z

6.4 hours after it, 197 km from the path. May 10, 1996.

Skew-T log-pSkew-T log-p diagram, Davenport, at 12:00Z on 1996-05-10Temperature 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 -4766, lifted condensation level 1258 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°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 1996-05-10The 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 13 square meters per square second, 0 to 6 km bulk shear 38 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
-4766 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1258 m above ground
0-6 km bulk shear
38 kt
0-1 km bulk shear
14 kt
0-1 km storm-relative helicity
13 m²/s²
0-3 km storm-relative helicity
71 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.9 K/km

Open this sounding in Storm Lab

The surface observations

Ottumwa (OTM), 25 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
04:00 UTC63.8663.86130° 6 kt1010.8-TSRA
05:00 UTC6563.86150° 14 kt1010.2TSRA FG
05:08 UTC170° 11 kt1010.2+TSRA SHRA FZFG
05:39 UTC320° 20 kt281013.2+TSRA SHRA
06:00 UTC65.8465310° 20 kt261012.9-TSRA FG
07:00 UTC6563350° 13 kt1012.2-TSRA

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

The radar

The Des Moines radar (KDMX), 110 km away, was scanning. The volume nearest the touchdown began at 05:37 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 1996 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

The other tornadoes of May 9, 1996

18 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 91:50 AM CDTF1Appanoose, IA0.735$70,000
May 92:40 AM CDTF1Davis, IA2.050$70,000
May 93:47 AM CDTF0Monroe, IA1.030$10,000
May 99:13 AM CDTF0Iberia Parish, LA2.520
May 96:20 PM CDTF0Gray, TX0.125
May 96:59 PM CDTF0Wheeler, TX5.0100
May 97:15 PM CDTF0Cloud, KS0.1400
May 97:17 PM CDTF0Cloud, KS0.150
May 97:22 PM CDTF0Wheeler, TX0.120
May 97:31 PM CDTF0Wheeler, TX0.675
May 98:10 PM CDTF0Washington, KS0.250
May 98:41 PM CDTF0Mercer, IL0.125
May 98:50 PM CDTF2Washington, KS1.5100$300,000
May 98:55 PM CDTF0Marshall, KS0.220$10,000
May 99:00 PM CDTF0Warren, IL0.225
May 99:10 PM CDTF1Reno, KS0.550
May 99:25 PM CDTF0Marshall, KS0.115
May 99:32 PM CDTF1Nemaha, KS0.575$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.