Tornadoes · United States · Illinois · 2004
F1 tornado, Prophetstown, Illinois, July 5, 2004
This F1 tornado ran 0.3 miles across Whiteside County on July 5, 2004, touching down at 3:52 PM CDT and reaching 30 yards wide. It killed nobody, and did $10,000 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.
F040 to 72 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
F173 to 112 mphthis tornado
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
F4207 to 260 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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
- July 5, 2004
- Touchdown
- 3:52 PM CDT (20:52 UTC)
- Path length
- 0.3 miles (0.5 km)
- Path width
- 30 yards (27 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $10,000
- County
- Whiteside County
- Touchdown point
- 41.620, -89.980
- Lift-off point
- 41.630, -89.980
- Record number
- 383
What the Weather Service recorded
A warm front moving north through Whiteside county began developing convection around 1430 CST, and a landspout developed out of the rapidly growing cumulus clouds just before 1500 CST. On the Baker Farm along Washington Road, southwest of Prophetstown, a machine shed had part of the roof torn off with the west wall blown down. Had the landspout moved 100 feet in either direction, grain bins, the farm house, and other outbuilding would have been in the path. The same shed was severely damaged by straight line winds in 1998. After damaging the machine shed, the landspout moved northwest 0.3 miles through a corn field and dissipated just short of some irrigation equipment. Landspout rated a low F1 with winds around 70 knots (80 mph). KDVN 88D data showed reflectivity returns of only 10-20 dbz.
Also from newspaper and insurance reports
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. One was issued for the county at another hour that day.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 02:07 UTC | 02:45 UTC | Tornado Warning | DVN |
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 20:21 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
8.9 hours before the tornado, 43 km from the path. July 5, 2004.
- Mixed-layer CAPE
- 477 J/kg
- Mixed-layer CIN
- -177 J/kg
- Surface CAPE
- 0 J/kg
- Mixed-layer LCL
- 1211 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km bulk shear
- 12 kt
- 0-1 km storm-relative helicity
- 12 m²/s²
- 0-3 km storm-relative helicity
- 81 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
- 0-3 km lapse rate
- 3.1 K/km
Davenport, (KDVN), 00:00Z
3.1 hours after it, 43 km from the path. July 6, 2004.
- Mixed-layer CAPE
- 1346 J/kg
- Mixed-layer CIN
- -8 J/kg
- Surface CAPE
- 2354 J/kg
- Mixed-layer LCL
- 1014 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km bulk shear
- 6 kt
- 0-1 km storm-relative helicity
- 41 m²/s²
- 0-3 km storm-relative helicity
- 88 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.3
- 0-3 km lapse rate
- 7.0 K/km
The surface observations
Sterling Rockfal (SQI), 28 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 18:55 UTC | 82.4 | 69.8 | 110° 9 kt | 1011.9 | ||
| 19:15 UTC | 82.4 | 68 | 100° 10 kt | 1012.5 | ||
| 19:35 UTC | 84.2 | 69.8 | 120° 8 kt | 14 | 1012.2 | |
| 19:55 UTC | 82.4 | 69.8 | 110° 7 kt | 1011.9 | ||
| 20:15 UTC | 82.4 | 69.8 | 120° 5 kt | 1011.9 | ||
| 20:35 UTC | 82.4 | 69.8 | 130° 8 kt | 1011.9 | VCTS | |
| 20:55 UTC | 82.4 | 69.8 | 120° 8 kt | 1011.5 | VCTS | |
| 21:15 UTC | 84.2 | 69.8 | 130° 8 kt | 1011.5 | VCTS | |
| 21:35 UTC | 80.6 | 69.8 | 100° 6 kt | 1011.5 | VCTS | |
| 21:55 UTC | 75.2 | 66.2 | 120° 9 kt | 16 | 1011.2 | |
| 22:15 UTC | 73.4 | 66.2 | 130° 7 kt | 1011.2 | ||
| 22:35 UTC | 75.2 | 68 | 100° 9 kt | 1011.5 |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Quad Cities radar (KDVN), 50 km away, was scanning. The volume nearest the touchdown began at 20:51 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 |
|---|---|---|---|---|
| 21:06 UTC | TORNADO | 6 Ssw Prophetstown | Whiteside, IL | TORNADO DAMAGED FARM MACHINE SHED, NO INJURIES. TOUCHED DOWN TWICE, ONCE IN OPEN FIELD AND SECOND TIME ON MACHINE SHED. FARM IS 6 MILES SOUTH ON WASHINGTON ROAD. THIS IS THE SAME TORNADO THAT WAS ORIGINALLY REPORTED 4 MI |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2004 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are
The other tornadoes of July 5, 2004
8 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| July 5 | 7:34 AM CDT | F1 | Miller, MO | 0.2 | 125 | $50,000 | ||
| July 5 | 7:37 AM CDT | F1 | Miller, MO | 0.2 | 125 | $10,000 | ||
| July 5 | 7:40 AM CDT | F1 | Miller, MO | 0.2 | 125 | $10,000 | ||
| July 5 | 3:50 PM CDT | F0 | Calhoun, IA | 0.2 | 30 | |||
| July 5 | 5:40 PM CDT | F0 | Howard, IA | 0.2 | 20 | $10,000 | ||
| July 5 | 6:35 PM CDT | F0 | Fayette, IA | 0.2 | 20 | |||
| July 5 | 8:42 PM CDT | F0 | Madison, IL | 0.1 | 40 | |||
| July 5 | 10:40 PM CDT | F0 | Woodford, IL | 0.1 | 10 |
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.