Tornadoes · United States · Iowa · 2004

F0 tornado, Webb to Spencer, Iowa, June 11, 2004

Name: F0 tornado, Webb to Spencer, Iowa, June 11, 2004
Start: 2004-06-11T20:03:00.000Z
Location: Webb to Spencer, Iowa

From Webb to Spencer, this F0 tornado ran 0.1 miles across Clay County on June 11, 2004, touching down at 3:03 PM CDT and reaching 50 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.

F040 to 72 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
F173 to 112 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
F4207 to 260 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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: June 11, 2004
Touchdown: 3:03 PM CDT (20:03 UTC)
Path length: 0.1 miles (0.2 km)
Path width: 50 yards (46 m)
Deaths: 0
Injuries: 0
County: Clay County
Touchdown point: 43.100, -94.980
Lift-off point: 43.100, -94.980
Record number: 283

What the Weather Service recorded

A tornado caused damage to crops, trees, and farm buildings, including windows blown out of a house.

A brief tornado caused no reported damage.

A tornado damaged crops, trees, and power lines.

A brief tornado caused no reported damage.

A tornado damaged trees. power lines, and several farm structures.

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

The warnings

18 minutes of warning. NWS FSD issued a tornado warning for this county at 19:45 UTC, 18 minutes before the tornado touched down, in force until 20:15 UTC.

Issued (UTC)	Expired	Product	Office
18:50 UTC	19:30 UTC	Severe Thunderstorm Warning	FSD
19:15 UTC	19:45 UTC	Tornado Warning	FSD
19:34 UTC	20:00 UTC	Severe Thunderstorm Warning	FSD
19:45 UTC	20:15 UTC	Tornado Warning	FSD
19:59 UTC	20:30 UTC	Tornado Warning	FSD
20:30 UTC	21:00 UTC	Tornado Warning	FSD

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, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 16:31 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.

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 Sioux Falls, SD wrote its last area forecast discussion before the tornado touched down at Jun 11, 3:00 PM CDT, 3 minutes earlier.

Area forecast discussion, Jun 11, 3:00 PM CDT, 3 minutes before

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
300 PM CDT FRI JUN 11 2004

.DISCUSSION...

SVR STORMS WILL EXIT THE FAR ERN PART OF FCST AREA BY ERY EVE. OTRW
DRY AIR COMNG IN AND LACK OF DECENT SHEAR SEEMS TO KILL ANY OTHER
TSTM DVLPMNT CHC NEXT CPL OR THREE HRS. SKIES SHUD GO MOCLR OVER
FCST AREA PRETTY QUICKLY THIS EVE WHERE THEY ARENT ALREADY. A FEW
CLDS ASSOCD WITH UPR LO MOVG NEWD MAY BRUSH NWRN CRNR OF CWA BUT
THIS CUD STILL LEAVE SKIES MOCLR. W/SW WNDS BRINGING IN THE DIRER
AIR SHUD DIE OFF PRETTY WELL DURG THE NGT AND SHUD LEAVE CONDS
PRETTY GOOD FOR BIG BALLOON RACE FSD AREA SAT MRNG.

BIGGER QSTNS COME WITH TSTM CHCS NEXT FEW DAYS. TSTM DVLPMNT PSBL
SAT AFTN AND EVE. INSTBLTY MRNGL ESPLY FOR SVR WITH LESS MOISTR
AVBL...AND WONDERING ABOUT SLGT RISK SVR SERN PART OF AREA ON DAY 2.
HWVR CONCEDE THAT SOME UPPR SUPPRT IS THERE...AND SHRT WV SHOWN
COMNG ACRS DURG SAT CUD EASILY BE STGR THAN MODELS FCST...SO WITH
SOME HALF DECENT HEATG EXPCTD WILL GO WITH THE CHC TSTMS AND KEEP
LIKELY SERN CRNR IN PART OF SLGT RISK AREA. THREAT SHUD TAPER OFF
INTO SRN PART OF AREA BY ERY SUN AND BE DONE BY LATE SUN.

THIS LEADS TO THE CHANGE OF TAKING OUT CHC TSTMS FOR SUN NGT AND
MOST OF MON. WILL THEN BRING MENTN BACK IN BY LATE MON AFTN AS FVRBL
LO AND MID LVL WAA PATTRN SETS UP. WILL CONT THIS THREAT INTO MON
NGT.

CONVECTN THREAT EXNTDED PD FOR TUE THRU FRI IS VERY QSTNBL WITH
MODELS STILL MAKING THE BIG CHANGES IN SOLNS FROM RUN TO RUN AND
BTWN EACH OTHER. CHC OF TSTMS WE HAVE BEEN CARRYNG FOR WED NGT AND
THU MAYBE SHUD BE MOVED A DAY OR DAY AND A HALF BASED ON SOME OF THE
LATEST MODELS. HWVR WILL LEAVE THIS ALONE ONE MORE DAY IN VIEW OF
ALMOST WILDLY CHANGING MODEL SOLNS IN THE EXTNDED RANGE. KEY IS FCST
UPR TROF THE DVLPS FROM THIS AREA INTO NRN GRTLKS BY THU AND WUD
SUGGEST DRY AND MILD PD. HWVR MODELS HAVE BEEN KNOWN TO UNDERDO
RIDGING IN PLAINS RECENTLY AND THIS CUD SLOW THINGS DOWN OR LEAD TO
MORE BIG CHANGES. IN ANY EVENT...BY FRI...LAST DAY OF EXTNDED...THE
DRY AND MILD PATTERN SHUD BE IN PLACE.

TEMPS THRU MOST OF FCST PD SHUD BE RELTVLY MILD. HWVR THINGS CUD GET
WRMR ABOUT MON IF ABV MENTND RDGNG GETS GOING STGR THAN MODELS
SHOW.

&&

.FSD...WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.

&&

WILLIAMS

Hazardous weather outlook, Jun 11, 11:36 AM CDT, 3 hours 27 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1136 AM CDT FRI JUN 11 2004

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-121200-
AURORA-BEADLE-BON HOMME-BROOKINGS-BRULE-BUENA VISTA IA-
CHARLES MIX-CHEROKEE IA-CLAY-CLAY IA-COTTONWOOD MN-DAKOTA NE-
DAVISON-DICKINSON IA-DIXON NE-DOUGLAS-GREGORY-HANSON-HUTCHINSON-
IDA IA-JACKSON MN-JERAULD-KINGSBURY-LAKE-LINCOLN-LINCOLN MN-
LYON IA-LYON MN-MCCOOK-MINER-MINNEHAHA-MOODY-MURRAY MN-NOBLES MN-
OBRIEN IA-OSCEOLA IA-PIPESTONE MN-PLYMOUTH IA-ROCK MN-SANBORN-
SIOUX IA-TURNER-UNION-WOODBURY IA-YANKTON-
1136 AM CDT FRI JUN 11 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA...
SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS...
TTHUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG OR JUST EAST OF
INTERSTATE 29 EARLY THIS AFTERNOON.  STORM WILL RAPIDLY DEVELOP
AND BECOME SEVERE WITH THE INITIAL THREAT BEING LARGE HAIL...IN
EXCESS OF GOLF BALL SIZE...NEAR THE SOUTH DAKOTA BORDER.  AS THE
STORMS MOVE EAST THIS AFTERNOON...THE THREAT FOR DAMAGING WINDS
WILL ALSO INCREASE. THE GREATEST THREAT FOR DAMAGING WINDS WILL
BE EAST OF LINE FROM MARSHALL MINNESOTA TO IDA GROVE IOWA.  THERE
WILL ALSO BE A RISK OF AN ISOLATED TORNADO DURING THE AFTERNOON.
THE THUNDERSTORMS ARE EXPECTED TO MOVE EAST OF THE AREA BY 7 PM.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

A COUPLE OF LOW PRESSURE SYSTEMS WILL MOVE EAST OVER THE AREA.
THE FIRST ONE SHOULD BRING A CHANCE OF THUNDERSTORMS LATE
SATURDAY AFTERNOON AND EVENING...AND THE SECOND SYSTEM SHOULD
AFFECT THE AREA LATE SUNDAY INTO MONDAY. THE BEST CHANCE OF
SEVERE THUNDERSTORMS WILL BE IN NORTHWEST IOWA...SOUTHEAST SOUTH
DAKOTA...AND FAR NORTHEAST NEBRASKA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE LIKELY AFTER 1 PM.

&&

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.CRH.NOAA.GOV/FSD. THIS INCLUDES THE GRAPHICAL HAZARDOUS
WEATHER OUTLOOK.

SCHUMACHER

In the hours before

Local storm report, Jun 11, 2:59 PM CDT, 4 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
259 PM CDT FRI JUN 11 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0107 PM     HAIL             CHEROKEE                42.75N 95.55W
06/11/2004  0.75 INCH        CHEROKEE           IA   TRAINED SPOTTER

0114 PM     HAIL             CHEROKEE                42.75N 95.55W
06/11/2004  0.88 INCH        CHEROKEE           IA   TRAINED SPOTTER

0147 PM     HAIL             5 W LINN GROVE          42.89N 95.34W
06/11/2004  0.75 INCH        BUENA VISTA        IA   PUBLIC

0209 PM     HAIL             3 SSE ROSSIE            42.97N 95.17W
06/11/2004  0.75 INCH        CLAY               IA   TRAINED SPOTTER

            DIME SIZE HAIL COVERING THE GROUND.

0219 PM     HAIL             GREENVILLE              43.02N 95.15W
06/11/2004  0.75 INCH        CLAY               IA   TRAINED SPOTTER

0223 PM     TORNADO          3 NE SIOUX RAPIDS       42.92N 95.11W
06/11/2004                   CLAY               IA   PUBLIC

0224 PM     TORNADO          2 W GILLETT GROVE       43.02N 95.07W
06/11/2004                   CLAY               IA   PUBLIC

0226 PM     TORNADO          5 NW MARATHON           42.91N 95.05W
06/11/2004                   BUENA VISTA        IA   TRAINED SPOTTER

            CONE SHAPED TORNADO

0228 PM     TORNADO          3 W WEBB                42.95N 95.07W
06/11/2004                   CLAY               IA   PUBLIC

0228 PM     TORNADO          3 N GILLETT GROVE       43.06N 95.04W
06/11/2004                   CLAY               IA   PUBLIC

0233 PM     TORNADO          2 NE MARATHON           42.88N 94.96W
06/11/2004                   BUENA VISTA        IA   EMERGENCY MNGR

            TORNADO A COUPLE HUNDRED YARDS WIDE

0246 PM     TORNADO          E WEBB                  42.95N 95.01W
06/11/2004                   CLAY               IA   EMERGENCY MNGR

            TORNADO ON COUNTY ROAD B63 JUST EAST OF WEBB

&&

TRM

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.

Minneapolis, MN (KMPX), 12:00Z

8.1 hours before the tornado, 224 km from the path. June 11, 2004.

Skew-T log-p

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.

Hodograph

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: -62099 J/kg
Surface CAPE: 1 J/kg
Mixed-layer LCL: 572 m above ground
0-6 km bulk shear: 18 kt
0-1 km bulk shear: 20 kt
0-1 km storm-relative helicity: -29 m²/s²
0-3 km storm-relative helicity: 16 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1
0-3 km lapse rate: 2.8 K/km

Open this sounding in Storm Lab

Minneapolis, MN (KMPX), 00:00Z

3.9 hours after it, 224 km from the path. June 12, 2004.

Skew-T log-p

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.

Hodograph

Mixed-layer CAPE: 53 J/kg
Mixed-layer CIN: -210 J/kg
Surface CAPE: 0 J/kg
Mixed-layer LCL: 1051 m above ground
0-6 km bulk shear: 46 kt
0-1 km bulk shear: 16 kt
0-1 km storm-relative helicity: 82 m²/s²
0-3 km storm-relative helicity: 216 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4
0-3 km lapse rate: 4.6 K/km

Open this sounding in Storm Lab

The radar

The Sioux Falls radar (KFSD), 151 km away, was scanning. The volume nearest the touchdown began at 20:00 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.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)	Report	Where	County	Remark
18:47 UTC	HAIL 0.75	5 W Linn Grove	Buena Vista, IA
18:47 UTC	HAIL 0.75	5 W Linn Grove	Buena Vista, IA
18:47 UTC	HAIL 0.75	5 W Linn Grove	Buena Vista, IA
19:09 UTC	HAIL 0.75	3 Sse Rossie	Clay, IA	DIME SIZE HAIL COVERING THE GROUND.
19:09 UTC	HAIL 0.75	3 Sse Rossie	Clay, IA	DIME SIZE HAIL COVERING THE GROUND.
19:09 UTC	HAIL 0.75	3 Sse Rossie	Clay, IA	DIME SIZE HAIL COVERING THE GROUND.
19:19 UTC	HAIL 0.75	Greenville	Clay, IA
19:19 UTC	HAIL 0.75	Greenville	Clay, IA
19:19 UTC	HAIL 0.75	Greenville	Clay, IA
19:20 UTC	TORNADO	2 N Marathon	Buena Vista, IA	STORM CHASER. CONE SHAPED WHILE ON THE GROUND WITH DEBRIS CLOUD VERY EVIDENT.
19:23 UTC	TORNADO	3 Ne Sioux Rapids	Clay, IA
19:23 UTC	TORNADO	3 Ne Sioux Rapids	Clay, IA
19:23 UTC	TORNADO	3 Ne Sioux Rapids	Clay, IA
19:24 UTC	TORNADO	2 W Gillett Grove	Clay, IA
19:24 UTC	TORNADO	2 W Gillett Grove	Clay, IA
19:24 UTC	TORNADO	2 W Gillett Grove	Clay, IA
19:26 UTC	TORNADO	5 Nw Marathon	Buena Vista, IA	CONE SHAPED TORNADO
19:26 UTC	TORNADO	5 Nw Marathon	Buena Vista, IA	CONE SHAPED TORNADO
19:26 UTC	TORNADO	5 Nw Marathon	Buena Vista, IA	CONE SHAPED TORNADO
19:28 UTC	TORNADO	3 N Gillett Grove	Clay, IA
19:28 UTC	TORNADO	3 N Gillett Grove	Clay, IA
19:28 UTC	TORNADO	3 N Gillett Grove	Clay, IA
19:28 UTC	TORNADO	3 W Webb	Clay, IA
19:28 UTC	TORNADO	3 W Webb	Clay, IA
19:28 UTC	TORNADO	3 W Webb	Clay, IA
19:33 UTC	TORNADO	2 Ne Marathon	Buena Vista, IA	TORNADO A COUPLE HUNDRED YARDS WIDE
19:33 UTC	TORNADO	2 Ne Marathon	Buena Vista, IA	TORNADO A COUPLE HUNDRED YARDS WIDE
19:33 UTC	TORNADO	2 Ne Marathon	Buena Vista, IA	TORNADO A COUPLE HUNDRED YARDS WIDE
19:40 UTC	HAIL 0.75	1 E Hartley	Obrien I, A
19:40 UTC	HAIL 0.75	1 E Hartley	Obrien I, A
19:40 UTC	HAIL 0.75	1 E Hartley	Obrien I, A
19:45 UTC	TORNADO	Webb	Clay, IA	245 PM TO 255 PM. 2 CONFIRMED TORNADES IN WEBB AREA. WINDOWS BLOWN OUT OF HOUSE. TREE AND CROP DAMAGE.
19:46 UTC	TORNADO	E Webb	Clay, IA	TORNADO ON COUNTY ROAD B63 JUST EAST OF WEBB
19:46 UTC	TORNADO	E Webb	Clay, IA	TORNADO ON COUNTY ROAD B63 JUST EAST OF WEBB
19:46 UTC	TORNADO	E Webb	Clay, IA	TORNADO ON COUNTY ROAD B63 JUST EAST OF WEBB
19:50 UTC	HAIL 1	7 E Ocheyedan	Osceola, IA
19:50 UTC	HAIL 1	7 E Ocheyedan	Osceola, IA
19:50 UTC	HAIL 1	7 E Ocheyedan	Osceola, IA
20:00 UTC	TORNADO	1 W Ruthven	Palo Alto, IA	ESTIMATED TO BE 1/4 MILE WIDE.
20:01 UTC	TORNADO	3 E Dickens	Clay, IA	TORNADO 1/4 MILE WIDE

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the track Every 2004 tornado in Iowa Every tornado in Iowa since 1950 Warnings in force in Iowa now The forecast where you are

The other tornadoes of June 11, 2004

37 more were confirmed in the United States that day.

Date	Time	Rating	Where	Path (mi)	Width (yd)	Injuries	Damage
June 11	2:20 PM CDT	F3	Buena Vista, IA	6.1	400		$50,000
June 11	2:49 PM CDT	F1	Clay, IA	1.8	100
June 11	2:59 PM CDT	F0	Lyon, MN	0.1	50
June 11	3:00 PM CDT	F1	Palo Alto, IA	9.0	450		$10,000
June 11	3:01 PM CDT	F0	Clay, IA	0.1	100
June 11	3:01 PM CDT	F1	Clay, IA	1.0	100
June 11	3:05 PM CDT	F0	Clay, IA	0.1	50
June 11	3:05 PM CDT	F2	Clay, IA	5.5	200		$500,000
June 11	4:12 PM EDT	F0	Albemarle, VA	0.2	50		$3,000
June 11	3:15 PM CDT	F1	Clay, IA	2.0	100
June 11	3:34 PM CDT	F1	Clay, IA	1.5	100
June 11	3:50 PM CDT	F1	Emmet, IA	6.0	200		$10,000
June 11	4:48 PM CDT	F0	Faribault, MN	6.0	100
June 11	5:17 PM CDT	F1	Mitchell, IA	4.0	60		$1,000
June 11	5:26 PM CDT	F1	Freeborn, MN	4.0	50
June 11	5:40 PM CDT	F0	Freeborn, MN	0.1	25
June 11	5:40 PM CDT	F0	Howard, IA	4.0	40		$100,000
June 11	5:56 PM CDT	F3	Howard, IA to MN	12.0	150		$190,000
June 11	7:16 PM EDT	F0	Brunswick, VA	0.5	50		$10,000
June 11	6:30 PM CDT	F0	Fillmore, MN	0.2	20
June 11	6:35 PM CDT	F0	Webster, IA	0.2	25
June 11	6:35 PM CDT	F0	Calhoun, IA	0.5	30
June 11	6:36 PM CDT	F0	Webster, IA	0.5	30
June 11	6:39 PM CDT	F0	Webster, IA	0.7	40
June 11	6:53 PM CDT	F0	Mower, MN	0.2	20
June 11	7:14 PM CDT	F0	Barnes, ND	0.6	25
June 11	7:20 PM CDT	F0	Webster, IA	0.7	40		$100,000
June 11	7:30 PM CDT	F0	Webster, IA	7.0	30
June 11	7:31 PM CDT	F0	Mower, MN	0.2	20
June 11	7:41 PM CDT	F0	Webster, IA	0.3	25
June 11	7:49 PM CDT	F0	Webster, IA	0.2	25
June 11	8:45 PM CDT	F0	Boone, IA	0.5	40
June 11	10:00 PM EDT	F1	Chowan, NC	6.0	30		$10,000
June 11	9:01 PM CDT	F0	Boone, IA	0.1	25
June 11	9:28 PM CDT	F2	Mitchell, TX	10.3	200	3	$250,000
June 11	10:43 PM EDT	F0	Pitt, NC	0.1	20
June 11	11:00 PM EDT	F0	Tyrrell, NC	0.1	20

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.