Alert archive / Illinois / Severe Thunderstorm Watches in 2000

Severe Thunderstorm Watch 649

August 6, 200025 counties in Illinois; 17 counties in Iowa; 12 counties in Wisconsin

The Storm Prediction Center issued this severe thunderstorm watch at Aug 6, 2000, 1:30 PM CDT for 25 counties in Illinois; 17 counties in Iowa; 12 counties in Wisconsin. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Aug 6, 2000, 1:30 PM CDT (18:30 UTC)
Expired
Aug 6, 2000, 7:00 PM CDT
In force
6 hr
Issued by
the Storm Prediction Center
All 54 counties

Cedar County, IA, Clinton County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Henry County, IA, Jackson County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Lee County, IA, Linn County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Washington County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Henderson County, IL, Henry County, IL, Jo Daviess County, IL, Kane County, IL, Kendall County, IL, Knox County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, McHenry County, IL, Mercer County, IL, Ogle County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Warren County, IL, Whiteside County, IL, Winnebago County, IL, Dane County, WI, Green County, WI, Jefferson County, WI, Kenosha County, WI, Lafayette County, WI, Milwaukee County, WI, Ozaukee County, WI, Racine County, WI, Rock County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Aug 6, 1:54 PM CDTSevere Thunderstorm WarningMKXGreen66 min
Aug 6, 2:07 PM CDTTornado WarningMKXGreen, Rock68 min
Aug 6, 2:47 PM CDTSevere Thunderstorm WarningILXKnox, Peoria43 min
Aug 6, 2:56 PM CDTSevere Thunderstorm WarningDVNRock Island, Whiteside49 min
Aug 6, 2:59 PM CDTSevere Thunderstorm WarningMKXDodge, Jefferson, Washington, Waukesha61 min
Aug 6, 3:05 PM CDTSevere Thunderstorm WarningILXMarshall, Stark55 min
Aug 6, 3:12 PM CDTSevere Thunderstorm WarningMKXWalworth63 min
Aug 6, 3:35 PM CDTSevere Thunderstorm WarningLOTLaSalle55 min
Aug 6, 3:40 PM CDTSevere Thunderstorm WarningDVNBureau, Putnam35 min
Aug 6, 3:56 PM CDTSevere Thunderstorm WarningLOTLee64 min
Aug 6, 4:18 PM CDTSevere Thunderstorm WarningLOTGrundy, Kendall, LaSalle57 min
Aug 6, 4:42 PM CDTSevere Thunderstorm WarningLOTDeKalb33 min
Aug 6, 4:44 PM CDTSevere Thunderstorm WarningLOTDuPage, Kane, Will61 min
Aug 6, 5:10 PM CDTSevere Thunderstorm WarningLOTCook35 min
Aug 6, 5:45 PM CDTSevere Thunderstorm WarningLOTCook15 min

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 6.5 hours before the alert went out and 56 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 2000-08-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1267 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 2000-08-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -12 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
1267 J/kg
Mixed-layer CIN
-99 J/kg
Mixed-layer LCL
1049 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
-12 m²/s²
0-3 km storm-relative helicity
27 m²/s²
Significant tornado parameter
-0.3
Supercell composite
-3.2

Open this sounding in Storm Lab

The text

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

197 
WWUS9 KMKC 061807
SEL9  
MKC WW 061758
IAZ000-ILZ000-WIZ000-LMZ000-070000-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 649
STORM PREDICTION CENTER NORMAN OK
1258 PM CDT SUN AUG 6 2000

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

   EASTERN IOWA                               
   NORTHERN ILLINOIS                           
   SOUTHERN WISCONSIN                          
   SOUTHWEST LAKE MICHIGAN                      

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 130 PM UNTIL 700
PM CDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 70 STATUTE MILES
NORTH AND SOUTH OF A LINE FROM 40 MILES SOUTH SOUTHWEST OF CEDAR
RAPIDS IOWA TO 30 MILES SOUTHEAST OF MILWAUKEE WISCONSIN.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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...TSTMS ARE BEGINNING TO DEVELOP ALONG PRE-FRONTAL WIND
SHIFT. 18Z RAOB FROM DVN SHOWED CAP TO HAVE WEAKENED...SO EXPLOSIVE
DEVELOPMENT IS EXPECTED DURING THE NEXT HOUR. STRONG INSTABILITY
AND SUFFICIENT DEEP LAYER SHEAR FOR SUPERCELLS SUGGEST THAT
DAMAGING WINDS AND LARGE HAIL ARE LIKELY...WITH EVENTUAL EVOLUTION
INTO A BOW ECHO BY LATE THIS AFTERNOON.


AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70
KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600.  MEAN STORM
MOTION VECTOR 29030.

...VESCIO

422,0920 433,0872 413,0872 401,0920

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 6, 4:00 PM CDTSevere Thunderstorm WatchSPCCass, Champaign, Christian, Coles, DeWitt, Douglas and 26 more6 hr
Aug 6, 2:45 PM CDTSevere Thunderstorm WatchSPCAdams, Appanoose, Clarke, Davis, Decatur, Iowa and 11 more5 hr

Nearby

Severe Thunderstorm Watches in Illinois, 2000Severe Thunderstorm Watches in Iowa, 2000Severe Thunderstorm Watches in Wisconsin, 2000Every severe thunderstorm 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.