Tornadoes · United States · Texas · 1997

F1 tornado, Brownsville Arpt to Bayview, Texas, April 4, 1997

From Brownsville Arpt to Bayview, this F1 tornado ran 0.5 miles across Cameron County on April 4, 1997, touching down at 3:25 AM CST and reaching 100 yards wide. It killed nobody, and did $40,000 of property damage.

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 mph

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. F173 to 112 mphthis tornado

    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
F1
Date
April 4, 1997
Touchdown
3:25 AM CST (09:25 UTC)
Path length
0.5 miles (0.8 km)
Path width
100 yards (91 m)
Deaths
0
Injuries
0
Property damage
$40,000
County
Cameron County
Touchdown point
25.970, -97.470
Lift-off point
25.970, -97.480
Record number
787

What the Weather Service recorded

Off duty commercial pilot reported tornado on ground.

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
10:08 UTC10:45 UTCTornado WarningBRO

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 Slight Risk. The outlook in force was issued at 06:46 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.

Brownsville Intl, TX (KBRO), 00:00Z

9.4 hours before the tornado, 11 km from the path. April 4, 1997.

Skew-T log-pSkew-T log-p diagram, Brownsville Intl, TX at 00:00Z on 1997-04-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1531 joules per kilogram, CIN -122, lifted condensation level 749 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, Brownsville Intl, TX at 00:00Z on 1997-04-04The 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 47 square meters per square second, 0 to 6 km bulk shear 50 knots.193958Sfc1 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
1531 J/kg
Mixed-layer CIN
-122 J/kg
Surface CAPE
1596 J/kg
Mixed-layer LCL
749 m above ground
0-6 km bulk shear
50 kt
0-1 km bulk shear
10 kt
0-1 km storm-relative helicity
47 m²/s²
0-3 km storm-relative helicity
18 m²/s²
Significant tornado parameter
0.2
Supercell composite
2.7
0-3 km lapse rate
4.3 K/km

Open this sounding in Storm Lab

Brownsville Intl, TX (KBRO), 12:00Z

2.6 hours after it, 11 km from the path. April 4, 1997.

Skew-T log-pSkew-T log-p diagram, Brownsville Intl, TX at 12:00Z on 1997-04-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1628 joules per kilogram, CIN -95, lifted condensation level 587 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, Brownsville Intl, TX at 12:00Z on 1997-04-04The 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 176 square meters per square second, 0 to 6 km bulk shear 53 knots.19395878Sfc1 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
1628 J/kg
Mixed-layer CIN
-95 J/kg
Surface CAPE
46 J/kg
Mixed-layer LCL
587 m above ground
0-6 km bulk shear
53 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
176 m²/s²
0-3 km storm-relative helicity
292 m²/s²
Significant tornado parameter
0.0
Supercell composite
6.8
0-3 km lapse rate
4.0 K/km

Open this sounding in Storm Lab

The surface observations

Brownsville International (BRO), 8 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
07:34 UTC73.473.4160° 10 kt1007.5
07:42 UTC73.473.4140° 12 kt1006.8
07:56 UTC7473150° 8 kt1007.1-TSRA BR
08:06 UTC73.473.4140° 9 kt1006.8
08:20 UTC73.473.4130° 7 kt1006.4
08:34 UTC73.473.4140° 7 kt1006.8
08:56 UTC7373130° 7 kt1006.4+TSRA BR
09:10 UTC73.473.4120° 7 kt1007.1
09:26 UTC73.471.6130° 22 kt321006.8
09:30 UTC71.671.6170° 26 kt391007.5
09:40 UTC69.868190° 16 kt301007.8
09:48 UTC6866.2170° 14 kt211007.5
09:56 UTC6867160° 13 kt1007.1TSRA BR
10:05 UTC6866.2160° 12 kt1007.1
10:56 UTC6967130° 11 kt1005.8-TSRA

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

This ground now

The live radar over the trackEvery 1997 tornado in TexasEvery tornado in Texas since 1950Warnings in force in Texas nowThe forecast where you are

The other tornadoes of April 4, 1997

12 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 44:30 AM CSTF0Cameron, TX0.150
April 411:04 AM CSTF0Tom Green, TX0.123
April 41:50 PM CSTF1Houston, TX0.350$40,000
April 42:05 PM CSTF0Houston, TX0.223$10,000
April 42:15 PM CSTF1Houston, TX0.333$40,000
April 42:30 PM CSTF0Trinity, TX0.120$10,000
April 42:50 PM CSTF0Trinity, TX0.120
April 44:45 PM CSTF1Webster Parish, LA20.0100$200,000
April 43:45 PM MSTF1Kimball, NE1.050
April 44:50 PM CSTF0Denton, TX0.130$10,000
April 45:20 PM CSTF1Columbia, AR7.0200$200,000
April 48:40 PM CSTF0Pushmataha, OK0.550$100,000

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.