Alert archive / Iowa / Tornado Watches in 2001

Tornado Watch 136

April 11, 200122 counties in Illinois; 46 counties in Iowa; 4 counties in Wisconsin

The Storm Prediction Center issued this tornado watch at Apr 11, 2001, 4:00 PM CDT for 22 counties in Illinois; 46 counties in Iowa; 4 counties in Wisconsin. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Apr 11, 2001, 4:00 PM CDT (21:00 UTC)
Expired
Apr 11, 2001, 10:00 PM CDT
In force
6 hr
Issued by
the Storm Prediction Center
All 72 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, Davis County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Grundy County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Kossuth County, IA, Lee County, IA, Linn County, IA, Louisa County, IA, Mahaska County, IA, Marshall County, IA, Muscatine County, IA, Poweshiek County, IA, Scott County, IA, Story County, IA, Tama County, IA, Van Buren County, IA, Wapello County, IA, Washington County, IA, Winneshiek County, IA, Wright County, IA, Bureau County, IL, Carroll County, IL, Ford County, IL, Henderson County, IL, Henry County, IL, Jo Daviess County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Marshall County, IL, Mercer County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Warren County, IL, Whiteside County, IL, Woodford County, IL, Crawford County, WI, Grant County, WI, Iowa County, WI, Lafayette County, WI

The radar

The Quad Cities radar (KDVN), 74 km from the middle of the area, began a volume at 21:03 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
Apr 11, 4:02 PM CDTSevere Thunderstorm WarningDMXPoweshiek28 min
Apr 11, 4:05 PM CDTTornado WarningDMXWapello20 min
Apr 11, 4:17 PM CDTTornado WarningDVNKeokuk28 min
Apr 11, 4:23 PM CDTSevere Thunderstorm WarningDMXCerro Gordo32 min
Apr 11, 4:27 PM CDTSevere Thunderstorm WarningDMXFranklin28 min
Apr 11, 4:31 PM CDTSevere Thunderstorm WarningDMXButler, Grundy44 min
Apr 11, 4:34 PM CDTSevere Thunderstorm WarningARXFloyd, Mitchell41 min
Apr 11, 4:35 PM CDTSevere Thunderstorm WarningDMXTama30 min
Apr 11, 4:38 PM CDTTornado WarningDVNWashington22 min
Apr 11, 4:42 PM CDTTornado WarningDVNBenton18 min
Apr 11, 4:43 PM CDTSevere Thunderstorm WarningDMXBlack Hawk37 min
Apr 11, 4:51 PM CDTTornado WarningDVNIowa, Johnson24 min
Apr 11, 4:58 PM CDTSevere Thunderstorm WarningARXChickasaw, Howard47 min
Apr 11, 5:01 PM CDTSevere Thunderstorm WarningDMXBremer39 min
Apr 11, 5:07 PM CDTTornado WarningDMXBlack Hawk23 min
Apr 11, 5:10 PM CDTTornado WarningDVNJohnson, Linn35 min
Apr 11, 5:11 PM CDTTornado WarningARXFayette64 min
Apr 11, 5:15 PM CDTTornado WarningDVNBuchanan30 min
Apr 11, 5:17 PM CDTSevere Thunderstorm WarningARXFloyd, Mitchell28 min
Apr 11, 5:43 PM CDTTornado WarningDVNLinn32 min
Apr 11, 6:00 PM CDTTornado WarningARXWinneshiek45 min
Apr 11, 6:26 PM CDTSevere Thunderstorm WarningARXAllamakee, Clayton64 min
Apr 11, 7:00 PM CDTSevere Thunderstorm WarningARXGrant, Richland60 min

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 9.0 hours before the alert went out and 76 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 2001-04-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 196 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 12:00Z on 2001-04-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 336 square meters per square second.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.
Mixed-layer CAPE
196 J/kg
Mixed-layer CIN
-182 J/kg
Mixed-layer LCL
822 m above ground
0-6 km bulk shear
63 kt
0-1 km storm-relative helicity
336 m²/s²
0-3 km storm-relative helicity
387 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.8

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
Apr 10, 7:00 PM CDTSevere Thunderstorm WatchSPCBond, Calhoun, Clay, Clinton, Crawford, Edwards and 21 more5 hr
Apr 11, 12:00 PM CDTTornado WatchSPCHenderson5 hr
Apr 11, 1:00 PM CDTTornado WatchSPCAdams, Brown, Calhoun, Cass, Fulton, Greene and 10 more6 hr
Apr 11, 2:00 AM CDTTornado WatchSPCCrawford, Fremont, Harrison, Mills, Monona, Pottawattamie and 1 more5 hr
Apr 11, 4:00 AM CDTSevere Thunderstorm WatchSPCAdair, Adams, Appanoose, Audubon, Boone, Carroll and 21 more5 hr
Apr 11, 10:45 AM CDTTornado WatchSPCAdams, Cass, Crawford, Fremont, Harrison, Mills and 8 more5 hr
Apr 11, 5:30 PM CDTTornado WatchSPCBuffalo, Chippewa, Clark, Dunn, Eau Claire, Jackson and 8 more6 hr

Nearby

Tornado Watches in Iowa, 2001Tornado Watches in Illinois, 2001Tornado Watches in Wisconsin, 2001Every tornado watch in 2001

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.