Alert archive / Iowa / Tornado Watches in 2003

Tornado Watch 662

July 6, 200368 counties in Iowa; 30 counties in Nebraska; 7 counties in South Dakota

The Storm Prediction Center issued this tornado watch at Jul 6, 2003, 9:20 PM CDT for 68 counties in Iowa; 30 counties in Nebraska; 7 counties in South Dakota. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Jul 6, 2003, 9:20 PM CDT (02:20 UTC)
Expired
Jul 7, 2003, 3:00 AM CDT
In force
6 hr
Issued by
the Storm Prediction Center
All 105 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Boone County, IA, Buena Vista County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cerro Gordo County, IA, Cherokee County, IA, Clarke County, IA, Clay County, IA, Crawford County, IA, Dallas County, IA, Decatur County, IA, Dickinson County, IA, Emmet County, IA, Floyd County, IA, Franklin County, IA, Fremont County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Jasper County, IA, Kossuth County, IA, Lucas County, IA, Lyon County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mills County, IA, Mitchell County, IA, Monona County, IA, Monroe County, IA, Montgomery County, IA, O'Brien County, IA, Osceola County, IA, Page County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Ringgold County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Warren County, IA, Wayne County, IA, Webster County, IA, Winnebago County, IA, Woodbury County, IA, Worth County, IA, Wright County, IA, Antelope County, NE, Boone County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Hamilton County, NE, Knox County, NE, Lancaster County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Otoe County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE, York County, NE, Bon Homme County, SD, Clay County, SD, Hutchinson County, SD, Lincoln County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Omaha radar (KOAX), 115 km from the middle of the area, began a volume at 02:19 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Warnings issued inside it

6 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Jul 7, 1:02 AM CDTSevere Thunderstorm WarningDMXEmmet43 min
Jul 7, 1:25 AM CDTSevere Thunderstorm WarningDMXFranklin20 min
Jul 7, 1:45 AM CDTSevere Thunderstorm WarningARXFloyd60 min
Jul 7, 2:08 AM CDTSevere Thunderstorm WarningDMXTama37 min
Jul 7, 2:27 AM CDTSevere Thunderstorm WarningARXMitchell48 min
Jul 7, 2:38 AM CDTSevere Thunderstorm WarningDMXButler22 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 2.3 hours before the alert went out and 115 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2003-07-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 4152 joules per kilogram.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.
HodographHodograph, Omaha, NE at 00:00Z on 2003-07-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 143 square meters per square second.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.
Mixed-layer CAPE
4152 J/kg
Mixed-layer CIN
-41 J/kg
Mixed-layer LCL
1702 m above ground
0-6 km bulk shear
43 kt
0-1 km storm-relative helicity
143 m²/s²
0-3 km storm-relative helicity
274 m²/s²
Significant tornado parameter
1.8
Supercell composite
103.4

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WWUS20 KWNS 070223
SEL2  
SPC WW 070220
IAZ000-NEZ000-070800-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 662 
NWS STORM PREDICTION CENTER NORMAN OK 
920 PM CDT SUN JUL 6 2003

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF 

       WESTERN AND CENTRAL IOWA
       EASTERN NEBRASKA

EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 920 PM UNTIL
300 AM CDT.

TORNADOES...HAIL TO 4 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 100 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 40 MILES WEST OF NORFOLK NEBRASKA TO 65 MILES
NORTH OF OTTUMWA IOWA.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA.
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.


OTHER WATCH INFORMATION...CONTINUE...WW 657...WW 658...WW 659...WW
660...WW 661...


DISCUSSION...ISOLATED SUPERCELLS EXPECTED TO DEVELOP IN ZONE OF
INCREASING WARM ADVECTION/LOW LEVEL CONVERGENCE OVER NW IA THIS
EVENING...WHILE OTHER STORMS DEVELOP/MOVE NEWD FROM S CNTRL NEB MCS.
 GREAT DEGREE OF SURFACE-BASED INSTABILITY /PER 00Z OAX RAOB/...
MODERATE VERTICAL SHEAR AND LARGE SCALE SUPPORT PROVIDED BY UPPER
IMPULSE NOW IN WRN NEB ALL SUGGEST LIKELIHOOD FOR VERY LARGE
HAIL/HIGH WIND AND A COUPLE TORNADOES. ACTIVITY SHOULD CONSOLIDATE
INTO A LARGE/COMPLEX MCS...WITH BOWING SEGMENTS AND OVERALL MOVEMENT
TOWARD THE ESE.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 4 INCHES. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600.
MEAN STORM MOTION VECTOR 29030.


...CORFIDI

432,0981 432,0922 403,0922 403,0981

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 6, 7:45 PM CDTTornado WatchSPCClay, Dickinson, Lyon, O'Brien, Osceola, Sioux6 hr
Jul 6, 8:57 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Boone, Buena Vista, Calhoun and 35 more3 hr
Jul 6, 11:06 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Audubon, Boone, Buena Vista and 62 more114 min
Jul 7, 1:25 AM CDTMesoscale DiscussionSPCAllamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 16 more95 min
Jul 7, 2:40 AM CDTSevere Thunderstorm WatchSPCAllamakee, Benton, Black Hawk, Bremer, Buchanan, Chickasaw and 12 more4 hr
Jul 7, 4:22 AM CDTMesoscale DiscussionSPCAllamakee, Black Hawk, Bremer, Buchanan, Chickasaw, Clayton and 5 more83 min
Jul 7, 6:23 AM CDTMesoscale DiscussionSPCCedar, Clinton, Delaware, Dubuque, Iowa, Jackson and 5 more97 min
Jul 7, 12:14 PM CDTMesoscale DiscussionSPCClinton, Des Moines, Lee, Louisa, Muscatine, Scott61 min
Jul 7, 2:35 PM CDTMesoscale DiscussionSPCAllamakee, Clayton, Delaware, Dubuque115 min
Jul 7, 3:30 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Audubon, Benton, Cass and 31 more3 hr
Jul 7, 3:35 PM CDTSevere Thunderstorm WatchSPCAdair, Adams, Audubon, Benton, Cass, Cedar and 29 more5 hr
Jul 7, 3:52 PM CDTMesoscale DiscussionSPCBanner, Chase, Cheyenne, Deuel, Kimball, Perkins and 1 more2 hr
Jul 7, 4:16 PM CDTMesoscale DiscussionSPCAdams, Arthur, Boone, Buffalo, Butler, Cass and 49 more2 hr
Jul 7, 6:00 PM CDTSevere Thunderstorm WatchSPCArthur, Banner, Box Butte, Chase, Cheyenne, Deuel and 17 more6 hr

Nearby

Tornado Watches in Iowa, 2003Tornado Watches in Nebraska, 2003Tornado Watches in South Dakota, 2003Every tornado watch in 2003

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.