F0 tornado, Merrill, Wisconsin, July 30, 2002

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.

Rating

F0

Date

July 30, 2002

Touchdown

7:08 PM CDT (00:08 UTC)

Path length

9.0 miles (14.5 km)

Path width

200 yards (183 m)

Deaths

0

Injuries

0

Property damage

$100,000

County

Lincoln County

Touchdown point

45.250, -89.680

Lift-off point

45.280, -89.550

Record number

790

Thunderstorms moved through Wisconsin in very warm and unstable air ahead of a cold front. Severe thunderstorm winds and tornadoes downed trees and power lines and damaged buildings across a large swath of central, north central and east central Wisconsin. Thousands of trees and power lines were downed by high winds from the storms. An 11 year old Boy Scout was killed and another was seriously injured when trees landed on their tent at Camp Napowan (Waushara co.).High winds pushed a house off its foundation and blew a boat and trailer into a neighbor's yard near Merrill (Lincoln co.). Some downed trees damaged or destroyed buildings or vehicles when they fell. A church steeple was toppled by high winds and a tree landed on an SUV, boat and trailer in Neenah (Winnebago co.) According to utility company news releases, nearly 20,000 customers were without power at some time during the storms. As of noon the next day there were still about 3,250 customers in the Green Bay (Brown co.) area without electricity.The hardest hit areas appeared to be in Marathon, Lincoln, Shawano and Oconto counties. Three of the four confirmed tornadoes touched down in Lincoln county and the other touched down in Marathon county. A tornado that touched down 5 miles north of Merrill (Lincoln co.) skipped along the ground for 9 miles, destroying a barn and another structure, tearing roofs from some buildings and moving others from their foundations. Another tornado briefly touched down about 8.5 miles northeast of Merrill demolishing a mobile home and snapping trees and tree limbs. The other Lincoln county tornado touched down 10 miles northwest of Merrill and skipped along the ground for 1.25 miles. A tornado skipped along the ground for 2 miles in Mosinee (Marathon co.) causing significant tree damage on a hill east of the Wisconsin River.

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

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.

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 Storm Prediction Center had this point in a Slight Risk. The outlook in force was issued at 20:12 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 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.

Merrill (RRL), 11 km from the path, in the two hours either side.

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

The Green Bay radar (KGRB), 146 km away, was scanning. The volume nearest the touchdown began at 00:08 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.

The live radar over the trackEvery 2002 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

3 more were confirmed in the United States that day.

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.

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