Tornadoes · United States · Texas · 1998

F0 tornado, Wimberley, Texas, April 8, 1998

This F0 tornado ran 0.5 miles across Hays County on April 8, 1998, touching down at 4:40 AM CDT and reaching 100 yards wide. It killed nobody.

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.

  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.

The record

Rating
F0
Date
April 8, 1998
Touchdown
4:40 AM CDT (09:40 UTC)
Path length
0.5 miles (0.8 km)
Path width
100 yards (91 m)
Deaths
0
Injuries
0
County
Hays County
Touchdown point
30.080, -98.050
Lift-off point
30.100, -98.050
Record number
772

What the Weather Service recorded

As severe thunderstorms moved eastward from the Texas Hill Country, sporadic bursts of high winds damaged trees and homes in the multi-county area. At times, the downbursts were accompanied by brief periods of hail. In general, windspeeds were estimated at well over 60 mph.

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)ExpiredProductOffice
09:30 UTC10:30 UTCSevere Thunderstorm WarningEWX
09:45 UTC10:45 UTCTornado WarningEWX

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 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.

Corpus Christi, TX (KCRP), 00:00Z

9.7 hours before the tornado, 271 km from the path. April 8, 1998.

Skew-T log-pSkew-T log-p diagram, Corpus Christi, TX at 00:00Z on 1998-04-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 896 joules per kilogram, CIN -130, lifted condensation level 852 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Corpus Christi, TX at 00:00Z on 1998-04-08The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 1 square meters per square second, 0 to 6 km bulk shear 69 knots.1939587897117Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
896 J/kg
Mixed-layer CIN
-130 J/kg
Surface CAPE
1124 J/kg
Mixed-layer LCL
852 m above ground
0-6 km bulk shear
69 kt
0-1 km bulk shear
9 kt
0-1 km storm-relative helicity
1 m²/s²
0-3 km storm-relative helicity
83 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5
0-3 km lapse rate
6.4 K/km

Open this sounding in Storm Lab

Corpus Christi, TX (KCRP), 12:00Z

2.3 hours after it, 271 km from the path. April 8, 1998.

Skew-T log-pSkew-T log-p diagram, Corpus Christi, TX at 12:00Z on 1998-04-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 207 joules per kilogram, CIN -594, lifted condensation level 1282 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Corpus Christi, TX at 12:00Z on 1998-04-08The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 92 square meters per square second, 0 to 6 km bulk shear 56 knots.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
207 J/kg
Mixed-layer CIN
-594 J/kg
Surface CAPE
932 J/kg
Mixed-layer LCL
1282 m above ground
0-6 km bulk shear
56 kt
0-1 km bulk shear
13 kt
0-1 km storm-relative helicity
92 m²/s²
0-3 km storm-relative helicity
126 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.8 K/km

Open this sounding in Storm Lab

The surface observations

San Marcos (Awos) (HYI), 28 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
08:16 UTC69.864.4200° 14 kt1005.1
08:37 UTC69.864.4200° 12 kt1005.4
08:56 UTC69.864.4230° 7 kt1006.1
09:17 UTC69.864.4240° 6 kt1006.1
09:36 UTC69.864.4260° 7 kt1006.8
09:56 UTC69.864.4230° 8 kt1007.1
10:16 UTC66.257.2320° 16 kt331008.8
10:36 UTC60.855.4320° 7 kt1008.5
10:57 UTC60.855.4320° 6 kt1008.5
11:17 UTC60.855.4340° 6 kt1008.5
11:37 UTC60.855.4320° 6 kt1008.5
11:56 UTC60.855.4300° 5 kt1008.5

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

This ground now

The live radar over the trackEvery 1998 tornado in TexasEvery tornado in Texas since 1950Warnings in force in Texas nowThe forecast where you are

The other tornadoes of April 8, 1998

13 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 84:57 AM CDTF0Hays, TX1.0150
April 87:43 AM CDTF1Claiborne Parish, LA0.2400$70,000
April 810:20 AM CDTF1Covington, AL0.130$30,000
April 86:20 PM CDTF0Crittenden, AR0.530$1,000
April 87:00 PM CDTF0Lawrence, TN0.5200
April 87:01 PM CDTF3Pickens, AL19.53001$820,000
April 87:42 PM CDTF5Oak Grove–Birmingham tornado, AL30.31,32032259$200 million
April 88:00 PM CDTF1Coffee, TN1.0200$50,000
April 88:23 PM CDTF1DeKalb, AL1.8100$100,000
April 88:56 PM CDTF2St. Clair, AL14.4200212$2.0 million
April 811:30 PM EDTF1Haralson, GA3.5200$300,000
April 812:20 AM EDTF2Cobb, GA3.52004$25 million
April 812:35 AM EDTF2DeKalb, GA19.0800110$75 million

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.