F0 tornado, Menominee, Illinois, May 16, 1999

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

May 16, 1999

Touchdown

9:00 PM CDT (02:00 UTC)

Path length

0.1 miles (0.2 km)

Path width

10 yards (9 m)

Deaths

0

Injuries

0

County

Jo Daviess County

Touchdown point

42.420, -90.530

Lift-off point

42.420, -90.530

Record number

594

Summary of events of May 16-17, 1999:On the 16th into the 17th two lines of thunderstorms developed: one north to south across western Iowa and the other repeatedly developed east to west from Butler to Clayton counties in northeast Iowa and moved east into northwest Illinois as a squall line. Thunderstorms along this line strengthened as they moved east, with several storms producing large hail, funnel clouds, damaging winds, flash flooding, and one confirmed tornado.The tornado (an F0) was spotted near Menominee in Jo Daviess County. hail as large as golf balls fell in East Dubuque (also in Jo Daviess County). Severe thunderstorm winds caused structural damage across portions of Stephenson, Whiteside, Carroll, Henry, and Bureau Counties. The costliest and most dramatic damage, however, did not come from tornadoes or hail but rather from flash flooding. Several inches of rain fell over portions of East Dubuque in only a few hours, causing a major flash flood in downtown. Water flowed down a street and into the Mississippi River, ripping up pavement and washing away cars as it went. See preceding individual Storm Data entries for further details and additional reports.

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 00:33 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.

Dubuque (DBQ), 15 km from the path, in the two hours either side.

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

The Quad Cities radar (KDVN), 90 km away, was scanning. The volume nearest the touchdown began at 02:02 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.

The live radar over the trackEvery 1999 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

24 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.