Alert archive / Illinois / Severe Thunderstorm Watches in 2003

Severe Thunderstorm Watch 781

July 20, 200327 counties in Illinois; Lee County, Iowa; 8 counties in Missouri

The Storm Prediction Center issued this severe thunderstorm watch at Jul 20, 2003, 11:30 PM CDT for 27 counties in Illinois; Lee County, Iowa; 8 counties in Missouri. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Jul 20, 2003, 11:30 PM CDT (04:30 UTC)
Expired
Jul 21, 2003, 5:00 AM CDT
In force
6 hr
Issued by
the Storm Prediction Center
All 36 counties

Lee County, IA, Adams County, IL, Brown County, IL, Cass County, IL, Champaign County, IL, DeWitt County, IL, Douglas County, IL, Ford County, IL, Fulton County, IL, Hancock County, IL, Iroquois County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, Mason County, IL, McDonough County, IL, McLean County, IL, Menard County, IL, Morgan County, IL, Peoria County, IL, Piatt County, IL, Pike County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Tazewell County, IL, Vermilion County, IL, Woodford County, IL, Clark County, MO, Knox County, MO, Lewis County, MO, Marion County, MO, Monroe County, MO, Ralls County, MO, Scotland County, MO, Shelby County, MO

The radar

The Lincoln radar (KILX), 90 km from the middle of the area, began a volume at 04:29 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

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

IssuedProductOfficeCountiesLasted
Jul 21, 12:41 AM CDTSevere Thunderstorm WarningLSXMarion, Shelby49 min
Jul 21, 12:59 AM CDTSevere Thunderstorm WarningLSXAdams46 min
Jul 21, 1:13 AM CDTSevere Thunderstorm WarningILXKnox, Peoria, Stark62 min
Jul 21, 1:34 AM CDTSevere Thunderstorm WarningILXFulton26 min
Jul 21, 1:43 AM CDTSevere Thunderstorm WarningILXTazewell, Woodford62 min
Jul 21, 1:58 AM CDTSevere Thunderstorm WarningILXMcLean62 min
Jul 21, 2:14 AM CDTSevere Thunderstorm WarningILXLogan61 min
Jul 21, 2:16 AM CDTSevere Thunderstorm WarningLOTFord, Livingston44 min
Jul 21, 2:19 AM CDTFlash Flood WarningILXPeoria, Tazewell6 hr
Jul 21, 2:40 AM CDTSevere Thunderstorm WarningILXDeWitt, Macon65 min
Jul 21, 2:51 AM CDTSevere Thunderstorm WarningILXChampaign, Piatt54 min
Jul 21, 2:53 AM CDTSevere Thunderstorm WarningLOTIroquois37 min
Jul 21, 3:18 AM CDTFlash Flood WarningILXLogan3 hr
Jul 21, 3:37 AM CDTFlash Flood WarningILXDeWitt, Macon, Piatt6 hr
Jul 21, 3:50 AM CDTFlash Flood WarningILXChampaign, Vermilion6 hr
Jul 21, 3:54 AM CDTSevere Thunderstorm WarningILXSangamon51 min
Jul 21, 4:04 AM CDTFlash Flood WarningILXDouglas6 hr

Discussions around it

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

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 4.5 hours before the alert went out and 148 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, Davenport, at 00:00Z on 2003-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3041 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, Davenport, at 00:00Z on 2003-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 123 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
3041 J/kg
Mixed-layer CIN
-67 J/kg
Mixed-layer LCL
1003 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
123 m²/s²
0-3 km storm-relative helicity
251 m²/s²
Significant tornado parameter
1.5
Supercell composite
9.6

Open this sounding in Storm Lab

The text

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

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 20, 8:08 PM CDTMesoscale DiscussionSPCBureau, Carroll, Fulton, Hancock, Henderson, Henry and 15 more2 hr
Jul 20, 8:30 PM CDTTornado WatchSPCCarroll, Henry, Jo Daviess, Mercer, Rock Island, Whiteside6 hr
Jul 20, 9:48 PM CDTMesoscale DiscussionSPCBoone, Bureau, Cook, DeKalb, DuPage, Grundy and 12 more117 min
Jul 20, 10:15 PM CDTSevere Thunderstorm WatchSPCBoone, Bureau, Cook, DeKalb, DuPage, Grundy and 12 more7 hr
Jul 20, 11:14 PM CDTMesoscale DiscussionSPCAdams, Brown, Cass, Champaign, DeWitt, Ford and 29 more2 hr
Jul 21, 1:56 AM CDTMesoscale DiscussionSPCChampaign, Douglas, Edgar, Ford, Iroquois, Macon and 2 more2 hr
Jul 21, 4:12 AM CDTMesoscale DiscussionSPCClay, Crawford, Edwards, Effingham, Franklin, Hamilton and 7 more2 hr
Jul 21, 3:26 PM CDTMesoscale DiscussionSPCCook94 min
Jul 20, 7:49 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Calhoun, Carroll, Cass and 17 more56 min
Jul 20, 8:50 PM CDTTornado WatchSPCAdair, Adams, Audubon, Boone, Carroll, Cass and 16 more5 hr
Jul 20, 7:05 PM CDTSevere Thunderstorm WatchSPCDouglas, Howell, Oregon, Ozark, Shannon5 hr
Jul 20, 10:43 PM CDTMesoscale DiscussionSPCHolt, Nodaway62 min

Nearby

Severe Thunderstorm Watches in Illinois, 2003Severe Thunderstorm Watches in Missouri, 2003Severe Thunderstorm Watches in Iowa, 2003Every severe thunderstorm 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.