Tornadoes · United States · North Dakota · 2002

F0 tornado, Leeds, North Dakota, July 31, 2002

This F0 tornado ran 0.2 miles across Benson County on July 31, 2002, touching down at 6:30 PM CDT and reaching 25 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
July 31, 2002
Touchdown
6:30 PM CDT (23:30 UTC)
Path length
0.2 miles (0.3 km)
Path width
25 yards (23 m)
Deaths
0
Injuries
0
County
Benson County
Touchdown point
48.180, -99.280
Lift-off point
48.180, -99.280
Record number
782

What the Weather Service recorded

A tornado touched down in open country.

A brief tornado touchdown snapped off several large tree branches. A farmer saw a brief swirling of dust near a tree row with a funnel above.

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

What forecasters said that day

The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Grand Forks, ND wrote its last area forecast discussion before the tornado touched down at Jul 31, 2:10 PM CDT, 4 hours 20 minutes earlier.

Area forecast discussion, Jul 31, 2:10 PM CDT, 4 hours 20 minutes before
FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
210 PM CDT WED JUL 31 2002

MAIN FORECAST CHALLENGE IS CONVECTIVE THREAT WITH COLD FRONTAL
PASSAGE TONIGHT AND THEN WINDY/CCOLER CONDITIONS IN ITS WAKE. MODELS
IN FAIR AGREEMENT BUT AVN WAS TOO HIGH WITH SFC DEW POINTS WHILE ETA
OVERDONE WITH CURRENT QPF. SO CONTINUED TO FOLLOW A BLEND BETWEEN
ETA AND AVN FOR GRIDS.

19Z SFC MAP SHOWS SEVERAL DISTINCT AREAS OF LOW PRESSURE WITH
MULTIPLE BOUNDARIES IN PLACE ACROSS THE NORTHERN PLAINS. MAIN SFC
LOW REMAINS OVER SOUTH CENTRAL SD WITH WARM FRONT EXTENDING
NORTHEAST INTO CENTRAL MN. WEAK LOW IN SRN MANITOBA WITH PREFRONTAL
TROUGH LINE BACK TOWARD ANOTHER WEAK LOW IN ERN MT. ALREADY HAS BEEN
SOME CONVECTIVE DEVELOPMENT ALONG THIS BOUNDARY THIS AFTERNOON
SHOWING UP ON RADAR/SATELLITE IMAGERY. SOUTHERN PORTION OF FA
REMAINS CAPPED LIMITING CONVECTIVE DEVELOPMENT ALONG THE WARM FRONT
SO FAR TODAY. NORTHERN FA NOT CAPPED AND HAVE FINALLY SEEN SOME
MOISTURE RETURN/SFC HEATING. MSAS SHOWING THIS AREA QUITE
UNSTABLE WITH COMPUTED SFC LIS NEAR -9. STILL WAITING TO SEE HOW
MUCH CONVERGENCE THIS BOUNDARY WILL PROVIDE AS MOST STATIONS SHOWING
WEAK SFC WIND FLOW. COLD FRONT TIMING STILL ON TAP FOR 06Z IN THE
VALLEY AND THIS WILL PROVIDE AMPLE LIFT. SO WILL KEEP A SCT THUNDER
MENTION IN ND ZONES THRU THE EVENING AND THRU MIDNIGHT ON THE MN
SIDE. WIDE AREA OF CLOUDS AND SHOWERS CURRENTLY BEHIND THE COLD
FRONT SO WILL KEEP SHOWER MENTION IN FOR THE REST OF TONIGHT IN THE
WAKE OF THE COLD FRONT. STRONG 850 MB COLD ADVECTION BEHIND THE
FRONT AS WELL WITH 40+ KNOTS...SO WILL UP WINDS A BIT TONIGHT INTO
EARLY THU.

WILL HANG ONTO A FEW SHOWERS OVER EASTERN MN COUNTIES EARLY THU AS
WELL WITH BOTH ETA AND AVN THEN SHOWING A GOOD DRY PUNCH WORKING IN.
LONG ADVERTISED COOL DOWN ON TAP FOR REMAINDER OF THE WEEK. 12Z AVN
KEEPS FRI NIGHT DRY NOW BUT ETA EXTENSION STILL KEEPS SOME WARM
FRONTAL PCPN. CANADIAN ALSO HAS SOME PCPN FRI NIGHT-SAT...SO WILL
KEEP CHANCE OF THUNDER FOR NOW.

.EXTENDED...
SEVERAL SHORT WAVES WILL AFFECT THE NRN PLAINS IN THE SUNDAY THROUGH
WEDNESDAY TIME FRAME...WITH TIMING AND ANY PCPN CHANCES THE
CHALLENGE.  12Z AVN/00Z MRF HAD SOME CONSISTENCY WITH 00Z CANADIAN
SO GENERALLY DID NOT DEVIATE FROM MODEL SOLNS. ONE SYSTEM MOVING
THRU THE NRN PLAINS MONDAY WITH THE NEXT ONE MOVING THRU LATE
WEDNESDAY. CARRIED CHC TSRA LATE SUNDAY NIGHT IN WARM ADVECTION THEN
CONTINUED CHC POPS THRU MON NIGHT AND AGAIN ON WEDNESDAY.  TEMPS
WILL BE NEAR OR TAD BELOW SEASONAL NORMALS AS REAL HOT AIR STAYS
SOUTH OF AREA.

.FGF...NONE.

GODON/RIDDLE

In the hours before

Local storm report, Jul 31, 2:22 PM CDT, 4 hours 8 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND FORKS, ND
222 PM CDT WED JUL 31 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0600 AM    5 W TENNEY                MN   WIND DAMAGE
07/31/02   WILKIN                         3 INCH BRANCHES DOWN
Local storm report, Jul 31, 2:22 PM CDT, 4 hours 8 minutes before
PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE GRAND FORKS, ND
222 PM CDT WED JUL 31 2002

CORRECTED FOR TIME

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0545 AM    5 W TENNEY                MN   WIND DAMAGE
07/31/02   WILKIN                         3 INCH BRANCHES DOWN
Local storm report, Jul 31, 6:21 PM CDT, 9 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND FORKS, ND
621 PM CDT WED JUL 31 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0600 PM    3 S LEEDS                 ND   TORNADO
07/31/02   BENSON                         BRIEF TOUCHDOWN REPORTED 3
                                          MILES SOUTH OF LEEDS BY
                                          SPOTTER

0611 PM    LEEDS                     ND   2.00 INCH HAIL
07/31/02   BENSON

ME

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.

Bismarck Municip, ND (KBIS), 12:00Z

11.5 hours before the tornado, 190 km from the path. July 31, 2002.

Skew-T log-pSkew-T log-p diagram, Bismarck Municip, ND at 12:00Z on 2002-07-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 307 joules per kilogram, CIN -525, lifted condensation level 1640 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, Bismarck Municip, ND at 12:00Z on 2002-07-31The 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 97 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
307 J/kg
Mixed-layer CIN
-525 J/kg
Surface CAPE
3 J/kg
Mixed-layer LCL
1640 m above ground
0-6 km bulk shear
53 kt
0-1 km bulk shear
13 kt
0-1 km storm-relative helicity
97 m²/s²
0-3 km storm-relative helicity
161 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.6
0-3 km lapse rate
3.4 K/km

Open this sounding in Storm Lab

Bismarck Municip, ND (KBIS), 00:00Z

0.5 hours after it, 190 km from the path. August 1, 2002.

Skew-T log-pSkew-T log-p diagram, Bismarck Municip, ND at 00:00Z on 2002-08-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1400 joules per kilogram, CIN -53, lifted condensation level 2219 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, Bismarck Municip, ND at 00:00Z on 2002-08-01The 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 39 square meters per square second, 0 to 6 km bulk shear 63 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
1400 J/kg
Mixed-layer CIN
-53 J/kg
Surface CAPE
2482 J/kg
Mixed-layer LCL
2219 m above ground
0-6 km bulk shear
63 kt
0-1 km bulk shear
7 kt
0-1 km storm-relative helicity
39 m²/s²
0-3 km storm-relative helicity
144 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.9
0-3 km lapse rate
8.4 K/km

Open this sounding in Storm Lab

The surface observations

Devils_lake (DVL), 29 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
00:00 UTC

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

This ground now

The live radar over the trackEvery 2002 tornado in North DakotaEvery tornado in North Dakota since 1950Warnings in force in North Dakota nowThe forecast where you are

The other tornadoes of July 31, 2002

2 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 316:00 PM CDTF0Benson, ND0.225
July 316:50 PM CDTF0Ramsey, ND0.210

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.