Tornadoes · United States · Mississippi · 1999

F0 tornado, Tomnolen, Mississippi, May 5, 1999

This F0 tornado ran 1.0 miles across Webster County on May 5, 1999, touching down at 8:45 PM CDT and reaching 40 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
May 5, 1999
Touchdown
8:45 PM CDT (01:45 UTC)
Path length
1.0 miles (1.6 km)
Path width
40 yards (37 m)
Deaths
0
Injuries
0
County
Webster County
Touchdown point
33.480, -89.370
Lift-off point
33.480, -89.370
Record number
963

What the Weather Service recorded

This weak tornado crossed an open field and no damage was reported.

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.

Issued (UTC)ExpiredProductOffice
01:21 UTC02:10 UTCSevere Thunderstorm WarningJAN

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 Moderate Risk. The outlook in force was issued at 00:26 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.

Jackson, MS (KJAN), 00:00Z

1.8 hours before the tornado, 145 km from the path. May 6, 1999.

Skew-T log-pSkew-T log-p diagram, Jackson, MS at 00:00Z on 1999-05-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 3704 joules per kilogram, CIN -1, lifted condensation level 839 meters above ground. Wind barbs in knots down the right edge.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°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, Jackson, MS at 00:00Z on 1999-05-06The 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 247 square meters per square second, 0 to 6 km bulk shear 66 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
3704 J/kg
Mixed-layer CIN
-1 J/kg
Surface CAPE
3949 J/kg
Mixed-layer LCL
839 m above ground
0-6 km bulk shear
66 kt
0-1 km bulk shear
28 kt
0-1 km storm-relative helicity
247 m²/s²
0-3 km storm-relative helicity
293 m²/s²
Significant tornado parameter
7.4
Supercell composite
23.8
0-3 km lapse rate
6.5 K/km

Open this sounding in Storm Lab

Jackson, MS (KJAN), 12:00Z

10.2 hours after it, 145 km from the path. May 6, 1999.

Skew-T log-pSkew-T log-p diagram, Jackson, MS at 12:00Z on 1999-05-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -10420, lifted condensation level 1607 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°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, Jackson, MS at 12:00Z on 1999-05-06The 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 -121 square meters per square second, 0 to 6 km bulk shear 64 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
0 J/kg
Mixed-layer CIN
-10420 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1607 m above ground
0-6 km bulk shear
64 kt
0-1 km bulk shear
20 kt
0-1 km storm-relative helicity
-121 m²/s²
0-3 km storm-relative helicity
22 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

Greenwood/Leflore (GWO), 66 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
23:53 UTC8473170° 14 kt997.6-TSRA
00:16 UTC82.473.4290° 15 kt27999.3
00:21 UTC73.469.8300° 18 kt271002.4
00:29 UTC69.864.4230° 20 kt251001.4
00:34 UTC69.864.4230° 22 kt301001
00:42 UTC69.866.2190° 17 kt291000.7
00:53 UTC6966180° 21 kt291000.3TSRA BR
01:02 UTC69.866.2230° 20 kt331000.7
01:13 UTC69.864.4210° 19 kt271000
01:28 UTC69.864.4180° 16 kt998.6
01:53 UTC7065220° 15 kt201000TSRA
02:53 UTC 1000.7TS
03:10 UTC6866.2200° 14 kt1002.4

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

This ground now

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

The other tornadoes of May 5, 1999

15 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 54:00 PM MDTF0Daggett, UT1.030
May 55:30 PM CDTF0Lincoln, WI0.10$10,000
May 56:05 PM CDTF1Marion, IL0.204
May 56:40 PM ESTF2Pike, IN1.3150$10,000
May 56:45 PM ESTF2Pike, IN3.0200$100,000
May 56:45 PM CDTF0Stewart, TN0.5100
May 56:58 PM CDTF0Montgomery, TN0.5100
May 57:00 PM CDTF0Yazoo, MS1.040
May 57:20 PM CDTF0Humphreys, MS1.040$2,000
May 57:20 PM CDTF1Leflore, MS1.050$10,000
May 58:20 PM CDTF4Perry, TN6.05803$290,000
May 59:45 PM CDTF1Davidson, TN0.1100$10,000
May 59:58 PM CDTF1Davidson, TN0.1100$1,000
May 510:36 PM CDTF2Sumner, TN0.722017$1.0 million
May 511:30 PM CDTF0Logan, KY0.150

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.