Alert archive / Iowa / Tornado Watches in 2000

Tornado Watch 264

May 11, 20008 counties in Illinois; 31 counties in Iowa; 5 counties in Wisconsin

The Storm Prediction Center issued this tornado watch at May 11, 2000, 6:45 PM CDT for 8 counties in Illinois; 31 counties in Iowa; 5 counties in Wisconsin. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
May 11, 2000, 6:45 PM CDT (23:45 UTC)
Expired
May 12, 2000, 12:00 AM CDT
In force
5 hr
Issued by
the Storm Prediction Center
All 44 counties

Allamakee County, IA, Benton County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Cedar County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clayton County, IA, Clinton County, IA, Delaware County, IA, Dubuque County, IA, Fayette County, IA, Floyd County, IA, Grundy County, IA, Howard County, IA, Iowa County, IA, Jackson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Mitchell County, IA, Muscatine County, IA, Poweshiek County, IA, Scott County, IA, Tama County, IA, Washington County, IA, Winneshiek County, IA, Worth County, IA, Bureau County, IL, Carroll County, IL, Henry County, IL, Jo Daviess County, IL, Lee County, IL, Rock Island County, IL, Stephenson County, IL, Whiteside County, IL, Crawford County, WI, Grant County, WI, Iowa County, WI, Lafayette County, WI, Richland County, WI

The radar

The Quad Cities radar (KDVN), 119 km from the middle of the area, began a volume at 23:47 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

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

IssuedProductOfficeCountiesLasted
May 11, 6:48 PM CDTTornado WarningDMXButler17 min
May 11, 6:53 PM CDTSevere Thunderstorm WarningDMXBlack Hawk, Bremer32 min
May 11, 6:56 PM CDTTornado WarningDMXBlack Hawk29 min
May 11, 7:00 PM CDTSevere Thunderstorm WarningARXChickasaw30 min
May 11, 7:15 PM CDTSevere Thunderstorm WarningARXFayette60 min
May 11, 7:21 PM CDTTornado WarningDMXBlack Hawk29 min
May 11, 7:31 PM CDTTornado WarningDVNBuchanan29 min
May 11, 7:44 PM CDTTornado WarningDMXBlack Hawk31 min
May 11, 7:58 PM CDTSevere Thunderstorm WarningARXAllamakee62 min
May 11, 7:58 PM CDTTornado WarningDVNBuchanan32 min
May 11, 8:12 PM CDTSevere Thunderstorm WarningARXFayette78 min
May 11, 8:13 PM CDTTornado WarningDMXBlack Hawk32 min
May 11, 8:25 PM CDTTornado WarningARXClayton35 min
May 11, 8:30 PM CDTTornado WarningDVNBuchanan45 min
May 11, 8:46 PM CDTSevere Thunderstorm WarningARXCrawford59 min
May 11, 8:50 PM CDTSevere Thunderstorm WarningARXWinneshiek40 min
May 11, 9:04 PM CDTTornado WarningARXCrawford41 min
May 11, 9:06 PM CDTTornado WarningDVNDelaware39 min
May 11, 9:12 PM CDTFlash Flood WarningDMXBlack Hawk3 hr
May 11, 9:19 PM CDTSevere Thunderstorm WarningDVNBuchanan41 min
May 11, 9:23 PM CDTSevere Thunderstorm WarningMKXIowa, Sauk67 min
May 11, 9:48 PM CDTSevere Thunderstorm WarningDVNDelaware42 min
May 11, 10:42 PM CDTSevere Thunderstorm WarningDVNDubuque48 min

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 11.8 hours before the alert went out and 121 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 12:00Z on 2000-05-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 12:00Z on 2000-05-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 172 square meters per square second.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.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
938 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
172 m²/s²
0-3 km storm-relative helicity
291 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

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

861 
WWUS9 KMKC 112315
SEL4  
MKC WW 112306
IAZ000-ILZ000-WIZ000-120500-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 264
STORM PREDICTION CENTER NORMAN OK
606 PM CDT THU MAY 11 2000

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

   EASTERN IOWA                               
   NORTHWEST ILLINOIS                           
   SOUTHWEST WISCONSIN                          

EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 645 PM UNTIL
MIDNIGHT CDT.

TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 90 STATUTE MILES EAST AND WEST
OF A LINE FROM 75 MILES NORTH NORTHEAST OF WATERLOO IOWA TO 20
MILES SOUTHWEST OF MOLINE ILLINOIS.

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.


DISCUSSION...VERY UNSTABLE AIRMASS WITH CAPES TO 5000 J/KG JUST
AHEAD OF SFC LOW CENTRAL IA.  STORMS RAPIDLY DEVELOPING N AND E OF
LOW IN AREA OF BEST LOW LEVEL CONVERGENCE.  WITH FAVORABLE VEERING
SHEAR PROFILES...TORNADIC SUPERCELLS LIKELY ALONG WITH VERY LARGE
HAIL.


AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. 
MEAN STORM MOTION VECTOR 24035.


...HALES

433,0900 411,0890 411,0923 433,0933

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 11, 5:00 AM CDTSevere Thunderstorm WatchSPCAllamakee, Bremer, Buena Vista, Butler, Cerro Gordo, Cherokee and 24 more6 hr

Nearby

Tornado Watches in Iowa, 2000Tornado Watches in Illinois, 2000Tornado Watches in Wisconsin, 2000Every tornado watch in 2000

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.