Tornadoes · United States · Wisconsin · 2009
EF0 tornado, Tennyson, Wisconsin, April 26, 2009
This EF0 tornado ran 0.1 miles across Grant County on April 26, 2009, touching down at 6:45 PM CDT and reaching 15 yards wide. It killed nobody.
The rating scale
Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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
- EF0
- Date
- April 26, 2009
- Touchdown
- 6:45 PM CDT (23:45 UTC)
- Lifted
- 6:46 PM CDT (23:46 UTC)
- On the ground
- 1 minutes
- Path length
- 0.1 miles (0.2 km)
- Path width
- 15 yards (14 m)
- Deaths
- 0
- Injuries
- 0
- County
- Grant County
- Touchdown point
- 42.690, -90.630
- Lift-off point
- 42.691, -90.628
- Record number
- 0904261745-01
What the Weather Service recorded
A strong low pressure system moved across northern Iowa in the evening hours of April 26th. This allowed severe thunderstorms and tornadoes to track across parts of eastern Iowa and into southwest Wisconsin. The severe storms produced funnel clouds and a brief tornado in rural Grant County.
A trained spotter witnessed a brief touch down of a tornado five miles north of Dickeyville in an open field with no damage.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
22 minutes of warning. NWS ARX issued a tornado warning for this county at 23:23 UTC, 22 minutes before the tornado touched down, in force until 00:30 UTC.
The county was under a tornado watch, issued at 22:05 UTC and running to 02:37 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 22:05 UTC | 02:37 UTC | Tornado Watch | ARX |
| 23:00 UTC | 08:36 UTC | Flash Flood Watch | ARX |
| 23:23 UTC | 00:30 UTC | Tornado Warning | ARX |
| 00:11 UTC | 06:00 UTC | Flash Flood Warning | ARX |
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, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 20:00 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), 12:00Z
11.8 hours before the tornado, 120 km from the path. April 26, 2009.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- -80104 J/kg
- Surface CAPE
- 0 J/kg
- Mixed-layer LCL
- 586 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 402 m²/s²
- 0-3 km storm-relative helicity
- 403 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
- 0-3 km lapse rate
- 3.0 K/km
Davenport, (KDVN), 00:00Z
0.2 hours after it, 120 km from the path. April 27, 2009.
- Mixed-layer CAPE
- 19 J/kg
- Mixed-layer CIN
- -108 J/kg
- Surface CAPE
- 501 J/kg
- Mixed-layer LCL
- 2074 m above ground
- 0-6 km bulk shear
- 34 kt
- 0-1 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 196 m²/s²
- 0-3 km storm-relative helicity
- 305 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
- 0-3 km lapse rate
- 7.7 K/km
The surface observations
Platteville (PVB), 15 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 21:53 UTC | 74.8 | 66.2 | 150° 11 kt | 1011.2 | ||
| 22:13 UTC | 74.3 | 65.5 | 150° 8 kt | 1011.2 | ||
| 22:33 UTC | 73.4 | 65.7 | 140° 9 kt | 1010.8 | ||
| 22:53 UTC | 73 | 65.3 | 120° 10 kt | 1010.5 | ||
| 23:13 UTC | 72 | 65.3 | 110° 8 kt | 1010.2 | ||
| 23:33 UTC | 71.8 | 65.7 | 100° 9 kt | 1010.2 | ||
| 23:53 UTC | 71.2 | 65.8 | 90° 7 kt | 1009.8 | ||
| 00:13 UTC | 70.5 | 66.2 | 70° 4 kt | 1010.2 | ||
| 00:33 UTC | 73.8 | 64 | 140° 8 kt | 1010.5 | ||
| 00:53 UTC | 73.4 | 64 | 130° 7 kt | 1010.2 | ||
| 01:13 UTC | 72.3 | 64.4 | 110° 9 kt | 1009.5 | ||
| 01:33 UTC | 71.6 | 64.4 | 120° 8 kt | 1009.1 |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Quad Cities radar (KDVN), 120 km away, was scanning. The volume nearest the touchdown began at 23:44 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.
What was reported nearby
Local storm reports within 60 km of the path, in the three hours either side.
| Time (UTC) | Report | Where | County | Remark |
|---|---|---|---|---|
| 23:45 UTC | TORNADO | 5 Nnw Dickeyville | Grant, WI | SPOTTER WITNESSED BRIEF TOUCH DOWN. |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2009 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are
The other tornadoes of April 26, 2009
10 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| April 26 | 1:39 AM CDT | EF1 | Garfield, OK | 1.5 | 500 | |||
| April 26 | 3:50 PM CDT | EF0 | Butler, KS | 0.5 | 50 | $3,000 | ||
| April 26 | 4:02 PM CDT | EF0 | Marion, KS | 0.6 | 70 | |||
| April 26 | 4:25 PM CDT | EF0 | Roger Mills, OK | 3.5 | 100 | |||
| April 26 | 4:34 PM CDT | EF2 | Roger Mills, OK | 10.3 | 300 | |||
| April 26 | 4:52 PM CDT | EF1 | Linn, IA | 21.0 | 100 | $1.0 million | ||
| April 26 | 5:28 PM CDT | EF0 | Woodward, OK | 0.2 | 50 | |||
| April 26 | 5:49 PM CDT | EF1 | Sedgwick, KS | 3.1 | 75 | 2 | $85,000 | |
| April 26 | 6:08 PM CDT | EF0 | Ringgold, IA | 1.3 | 30 | $100,000 | ||
| April 26 | 8:10 PM CDT | EF0 | Doniphan, KS | 0.1 | 25 |
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.