Tornadoes · United States · Missouri · 2001

F0 tornado, St Joseph, Missouri, September 20, 2001

This F0 tornado ran 0.1 miles across Buchanan County on September 20, 2001, touching down at 6:25 PM CDT. 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
September 20, 2001
Touchdown
6:25 PM CDT (23:25 UTC)
Path length
0.1 miles (0.2 km)
Path width
0 yards (0 m)
Deaths
0
Injuries
0
County
Buchanan County
Touchdown point
39.830, -94.850
Lift-off point
39.830, -94.850
Record number
1130

What the Weather Service recorded

Brief tornado touchdown. No injuries or damage.

Brief tornado touchdown reported at 4th and Dolman. No damage or injuries.

Brief tornado touchdown near 36th street and Farron. Tornado was reported to skip up and down. No injuries or damage.

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
22:42 UTC23:30 UTCSevere Thunderstorm WarningEAX
23:32 UTC00:15 UTCTornado WarningEAX

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 20:04 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.

Topeka, KS (KTOP), 12:00Z

11.4 hours before the tornado, 115 km from the path. September 20, 2001.

Skew-T log-pSkew-T log-p diagram, Topeka, KS at 12:00Z on 2001-09-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 773 joules per kilogram, CIN -197, lifted condensation level 1179 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, Topeka, KS at 12:00Z on 2001-09-20The 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 258 square meters per square second, 0 to 6 km bulk shear 33 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
773 J/kg
Mixed-layer CIN
-197 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1179 m above ground
0-6 km bulk shear
33 kt
0-1 km bulk shear
26 kt
0-1 km storm-relative helicity
258 m²/s²
0-3 km storm-relative helicity
314 m²/s²
Significant tornado parameter
0.0
Supercell composite
4.1
0-3 km lapse rate
3.5 K/km

Open this sounding in Storm Lab

Topeka, KS (KTOP), 00:00Z

0.6 hours after it, 115 km from the path. September 21, 2001.

Skew-T log-pSkew-T log-p diagram, Topeka, KS at 00:00Z on 2001-09-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1885 joules per kilogram, CIN -5, lifted condensation level 952 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 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, Topeka, KS at 00:00Z on 2001-09-21The 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 202 square meters per square second, 0 to 6 km bulk shear 43 knots.19395878Sfc1 km3 km6 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
1885 J/kg
Mixed-layer CIN
-5 J/kg
Surface CAPE
2065 J/kg
Mixed-layer LCL
952 m above ground
0-6 km bulk shear
43 kt
0-1 km bulk shear
23 kt
0-1 km storm-relative helicity
202 m²/s²
0-3 km storm-relative helicity
225 m²/s²
Significant tornado parameter
1.8
Supercell composite
8.7
0-3 km lapse rate
6.4 K/km

Open this sounding in Storm Lab

The surface observations

St. Joseph (STJ), 8 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
21:53 UTC8168220° 7 kt1010.5VCTS -RA
22:13 UTC80.668210° 7 kt1010.8
22:35 UTC80.669.8190° 6 kt1010.5VCTS
22:53 UTC8270200° 6 kt1010.2VCTS
23:17 UTC80.669.8210° 12 kt1009.8
23:53 UTC7869 3 kt1010.8
00:53 UTC73690° 0 kt1010.8

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

The radar

The Pleasant Hill radar (KEAX), 124 km away, was scanning. The volume nearest the touchdown began at 23:25 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.

This ground now

The live radar over the trackEvery 2001 tornado in MissouriEvery tornado in Missouri since 1950Warnings in force in Missouri nowThe forecast where you are

The other tornadoes of September 20, 2001

7 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
September 205:30 PM CDTF0Lucas, IA0.970$50,000
September 206:09 PM CDTF1Appanoose, IA0.550$10,000
September 206:20 PM CDTF0Woods, OK0.125
September 207:20 PM EDTF0Culpeper, VA0.225
September 206:34 PM CDTF0Buchanan, MO0.10
September 206:36 PM CDTF0Buchanan, MO0.10
September 206:55 PM CDTF0Buchanan, MO0.10

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.