Tornadoes · United States · Wisconsin · 2009
EF0 tornado, Saint Croix County, Wisconsin, August 19, 2009
This EF0 tornado ran 0.4 miles across Saint Croix County on August 19, 2009, touching down at 3:05 PM CDT and reaching 25 yards wide. It killed nobody, and did $25,000 of property damage.
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
- August 19, 2009
- Touchdown
- 3:05 PM CDT (20:05 UTC)
- Lifted
- 3:07 PM CDT (20:07 UTC)
- On the ground
- 2 minutes
- Path length
- 0.4 miles (0.6 km)
- Path width
- 25 yards (23 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $25,000
- County
- Saint Croix County
- Touchdown point
- 44.975, -92.690
- Lift-off point
- 44.980, -92.687
- Record number
- 0908191405-01
The warnings
12 minutes of warning. NWS MPX issued a tornado warning for this county at 19:53 UTC, 12 minutes before the tornado touched down, in force until 20:15 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 19:53 UTC | 20:15 UTC | Tornado Warning | MPX |
| 19:57 UTC | 20:45 UTC | Tornado Warning | MPX |
| 20:16 UTC | 20:45 UTC | Tornado Warning | MPX |
| 21:04 UTC | 21:30 UTC | Tornado Warning | MPX |
| 21:06 UTC | 21:45 UTC | Tornado Warning | MPX |
| 21:33 UTC | 22:00 UTC | Tornado Warning | MPX |
| 21:43 UTC | 22:18 UTC | Tornado Warning | MPX |
| 21:49 UTC | 00:16 UTC | Tornado Watch | MPX |
| 22:13 UTC | 22:35 UTC | Tornado Warning | MPX |
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 General Thunderstorms Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 21:34 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.
Minneapolis, MN (KMPX), 12:00Z
8.1 hours before the tornado, 73 km from the path. August 19, 2009.
- Mixed-layer CAPE
- 368 J/kg
- Mixed-layer CIN
- -49 J/kg
- Surface CAPE
- 154 J/kg
- Mixed-layer LCL
- 615 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 121 m²/s²
- 0-3 km storm-relative helicity
- 68 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 3.0
- 0-3 km lapse rate
- 5.7 K/km
Minneapolis, MN (KMPX), 00:00Z
3.9 hours after it, 73 km from the path. August 20, 2009.
- Mixed-layer CAPE
- 53 J/kg
- Mixed-layer CIN
- -37 J/kg
- Surface CAPE
- 810 J/kg
- Mixed-layer LCL
- 682 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km bulk shear
- 17 kt
- 0-1 km storm-relative helicity
- 47 m²/s²
- 0-3 km storm-relative helicity
- 57 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
- 0-3 km lapse rate
- 6.5 K/km
The radar
The Minneapolis radar (KMPX), 71 km away, was scanning. The volume nearest the touchdown began at 20:02 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 |
|---|---|---|---|---|
| 19:57 UTC | TORNADO | 5 Se Ellsworth | Pierce, WI | DAMAGE SURVEY DETERMINED AN EF-0 TORNADO TOUCHED DOWN BRIEFLY JUST NORTH OF THE INTERSECTION OF COUNTY ROADS DD AND V. THE TORNADO KNOCKED DOWN A NARROW STRIP OF CORN FOR 0.2 MILE. |
| 20:05 UTC | TSTM WND DMG | 1 N Hudson | St. Croix, WI | LINE OF POWER POLES LEANING ONTO ROAD - ALMOST TOUCHING ROAD AT COUNTY RD. A AND DORWIN RD. EVENT TIME IS ESTIMATED. |
| 20:05 UTC | TSTM WND DMG | Hudson | St. Croix, WI | TREES DOWN AT COUNTY RD. UU AND LARSON LANE. TIME OF EVENT IS ESTIMATED. |
| 20:05 UTC | TORNADO | 1 Nw Hudson | St. Croix, WI | TREES DOWN AT COUNTY ROAD UU AND LARSON LANE. TRACK LENGTH WAS APPROXIMATELY ONE THIRD OF A MILE. TIME OF EVENT IS ESTIMATED. |
| 20:05 UTC | TORNADO | Hudson | St. Croix, WI | TREES DOWN AT COUNTY RD. UU AND LARSON LANE. TIME OF EVENT IS ESTIMATED. |
| 20:30 UTC | TSTM WND DMG | 1 E Hudson | St. Croix, WI | 4 INCH BRANCHES IN ROAD AND WHOLE TREES DOWN ON HWY 12 ONE HALF TO ONE MILE EAST OF HUDSON. |
| 20:58 UTC | TORNADO | 3 Sw Emerald | St. Croix, WI | TORNADO TOUCHED DOWN BRIEFLY SEVERAL TIMES AS IT TRACKED NORTHWARD ALONG 250TH STREET FOR 1.4 MILES. VEGETATION WAS OCCASIONALLY TORN UP AND TOSSED IN THE AIR. |
| 21:11 UTC | TORNADO | Forest | St. Croix, WI | TORNADO ON GROUND AT HWY 64 AT HWY 63 INTERSECTION. |
| 21:15 UTC | TORNADO | 2 N Forest | St. Croix, WI | TORNADO STILL ON GROUND AT INTERSECTION OF 270TH STR. AND 20TH AVE. |
| 21:35 UTC | TSTM WND DMG | 3 Nw Esdaile | Pierce, WI | DAMAGE TO CROPS AND TREES AT THE INTERSECTION OF V AND D |
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 August 19, 2009
29 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| August 19 | 1:50 PM CDT | EF0 | Hennepin, MN | 4.3 | 500 | $500,000 | ||
| August 19 | 2:10 PM CDT | EF1 | Scott, IL | 15.1 | 250 | $395,000 | ||
| August 19 | 2:16 PM CDT | EF1 | Dakota, MN | 1.6 | 50 | $25,000 | ||
| August 19 | 2:40 PM CDT | EF1 | Washington, MN | 0.7 | 75 | $100,000 | ||
| August 19 | 2:46 PM CDT | EF2 | Morgan, IL | 19.1 | 440 | 3 | $4.1 million | |
| August 19 | 2:57 PM CDT | EF0 | Pierce, WI | 0.2 | 10 | |||
| August 19 | 3:07 PM CDT | EF0 | Anoka, MN | 0.0 | 10 | |||
| August 19 | 3:09 PM CDT | EF0 | Chickasaw, IA | 1.1 | 40 | $20,000 | ||
| August 19 | 3:17 PM CDT | EF1 | Sangamon, IL | 12.9 | 200 | $200,000 | ||
| August 19 | 3:19 PM CDT | EF3 | Sangamon, IL | 24.3 | 880 | 19 | $18 million | |
| August 19 | 3:25 PM CDT | EF0 | Washington, MN | 0.7 | 40 | $25,000 | ||
| August 19 | 3:50 PM CDT | EF0 | Howard, IA | 0.1 | 20 | |||
| August 19 | 3:50 PM CDT | EF0 | Fayette, IA | 3.5 | 40 | $22,000 | ||
| August 19 | 3:58 PM CDT | EF0 | Saint Croix, WI | 1.4 | 25 | |||
| August 19 | 4:00 PM CDT | EF0 | Chisago, MN | 0.9 | 200 | $100,000 | ||
| August 19 | 4:00 PM CDT | EF0 | Winneshiek, IA | 5.3 | 25 | $5,000 | ||
| August 19 | 4:04 PM CDT | EF0 | DeWitt, IL | 2.4 | 15 | $10,000 | ||
| August 19 | 4:11 PM CDT | EF0 | Saint Croix, WI | 1.7 | 25 | |||
| August 19 | 4:27 PM CDT | EF0 | McLean, IL | 2.5 | 20 | |||
| August 19 | 4:30 PM CDT | EF1 | Buchanan, IA | 2.2 | 100 | $75,000 | ||
| August 19 | 5:10 PM CDT | EF0 | Vermilion, IL | 4.7 | 50 | $80,000 | ||
| August 19 | 5:20 PM CDT | EF0 | Jones, IA | 0.1 | 50 | $5,000 | ||
| August 19 | 6:30 PM EDT | EF0 | Darke, OH | 0.1 | 20 | |||
| August 19 | 6:00 PM CDT | EF1 | Kane, IL | 1.0 | 40 | $25,000 | ||
| August 19 | 6:00 PM CDT | EF1 | Iroquois, IL | 2.8 | 50 | $100,000 | ||
| August 19 | 6:15 PM CDT | EF0 | Kane, IL | 0.8 | 30 | |||
| August 19 | 6:28 PM CDT | EF0 | Brown, MN | 3.7 | 20 | |||
| August 19 | 7:32 PM CDT | EF2 | Porter, IN | 4.0 | 60 | $1.5 million | ||
| August 19 | 12:05 AM CDT | EF1 | Texas, MO | 0.8 | 100 | 1 | $25,000 |
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.