F0 tornado, Velma, Oklahoma, April 6, 1998

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

April 6, 1998

Touchdown

8:45 PM CDT (01:45 UTC)

Path length

0.1 miles (0.2 km)

Path width

30 yards (27 m)

Deaths

0

Injuries

0

County

Stephens County

Touchdown point

34.430, -97.650

Lift-off point

34.430, -97.650

Record number

505

Summary of events of April 6, 1998:Severe thunderstorms moved across much of Oklahoma during the late afternoon and evening of the 6th. Hail as large as quarters, severe straight-line winds, and one tornado were reported. The tornado, an F0, touched down in a field in Stephens County. Severe thunderstorm wind gusts were measured at speeds up to 67 mph by the Oklahoma Mesonet site north of Mooreland in Woodward County. Reports of hail as large as quarters were received from near Grandfield in Tillman County, east of Laverne in Harper County, and south of Stratford in Garvin County. See preceding individual Storm Data entries for further details and additional reports.

Tornado touched down briefly in an open field and lasted less than one minute.

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

58 minutes of warning. NWS OUN issued a tornado warning for this county at 00:47 UTC, 58 minutes before the tornado touched down, in force until 01:45 UTC.

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 Moderate Risk. The outlook in force was issued at 19:29 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.

The Norman radar (KTLX), 106 km away, was scanning. The volume nearest the touchdown began at 01:47 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 1998 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are

5 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.