Alert archive / Illinois / Tornado Warnings in 2011

Tornado Warning 23, NWS Chicago, IL

August 2, 2011DeKalb County, Lee County, Ogle County, Illinois

NWS Chicago, IL issued this tornado warning at Aug 2, 2011, 8:45 PM CDT for DeKalb County, Lee County, Ogle County, Illinois. It was in force for 34 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 2, 2011, 8:45 PM CDT (01:45 UTC)
Expired
Aug 2, 2011, 9:19 PM CDT
In force
34 min
Issued by
NWS Chicago, IL
Area
Storm-based polygon

Counties DeKalb County, IL, Lee County, IL, Ogle County, IL

The radar

The Chicago radar (KLOT), 87 km from the middle of the area, began a volume at 01:48 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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 2, 5:22 PM CDTSevere Thunderstorm WatchSPC9 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 1.8 hours before the alert went out and 118 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 2011-08-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 6551 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Davenport, at 00:00Z on 2011-08-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 103 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
6551 J/kg
Mixed-layer CIN
-14 J/kg
Mixed-layer LCL
1103 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
103 m²/s²
0-3 km storm-relative helicity
189 m²/s²
Significant tornado parameter
3.8
Supercell composite
22.2

Open this sounding in Storm Lab

The text

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

486 
WFUS53 KLOT 030145
TORLOT
ILC037-103-141-030230-
/O.NEW.KLOT.TO.W.0023.110803T0145Z-110803T0230Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
845 PM CDT TUE AUG 2 2011

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* TORNADO WARNING FOR...
  WEST CENTRAL DE KALB COUNTY...
  NORTHEASTERN LEE COUNTY...
  SOUTHEASTERN OGLE COUNTY...

* UNTIL 930 PM CDT

* AT 841 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
  STORM WAS LOCATED NEAR FRANKLIN GROVE...OR NEAR DIXON...AND MOVING
  SOUTHEAST AT 25 MPH.

* LOCATIONS IMPACTED INCLUDE...
  ROCHELLE...FRANKLIN GROVE...ASHTON...WEST BROOKLYN...STEWARD...
  COMPTON AND LEE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 4187 8884 4172 8897 4163 8914 4181 8950
      4198 8930
TIME...MOT...LOC 0146Z 298DEG 23KT 4183 8935

$$

BIRK
3 follow-up statements
298 
WWUS53 KLOT 030158
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
858 PM CDT TUE AUG 2 2011

ILC037-103-141-030230-
/O.CON.KLOT.TO.W.0023.000000T0000Z-110803T0230Z/
OGLE IL-DE KALB IL-LEE IL-
858 PM CDT TUE AUG 2 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR EASTERN LEE...WEST CENTRAL
DE KALB AND SOUTHEASTERN OGLE COUNTIES UNTIL 930 PM CDT...

AT 855 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED NEAR FRANKLIN GROVE...OR 8 MILES NORTHEAST OF
WALTON...MOVING SOUTHEAST AT 25 MPH.

LOCATIONS IMPACTED INCLUDE...
  ROCHELLE...ASHTON...WEST BROOKLYN...STEWARD...COMPTON AND LEE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 4196 8921 4187 8884 4172 8897 4163 8914
      4179 8946
TIME...MOT...LOC 0158Z 298DEG 23KT 4179 8929

$$

BIRK
350 
WWUS53 KLOT 030212
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
912 PM CDT TUE AUG 2 2011

ILC037-141-030222-
/O.CAN.KLOT.TO.W.0023.000000T0000Z-110803T0230Z/
OGLE IL-DE KALB IL-
912 PM CDT TUE AUG 2 2011

...THE TORNADO WARNING FOR WEST CENTRAL DE KALB AND SOUTHEASTERN OGLE
COUNTIES IS CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE WARNED 
AREA.

LAT...LON 4187 8927 4181 8894 4176 8894 4172 8897
      4163 8914 4179 8946
TIME...MOT...LOC 0212Z 298DEG 23KT 4175 8918

$$

ILC103-030230-
/O.CON.KLOT.TO.W.0023.000000T0000Z-110803T0230Z/
LEE IL-
912 PM CDT TUE AUG 2 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR EASTERN LEE COUNTY UNTIL
930 PM CDT...

AT 910 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED 7 MILES EAST OF AMBOY...OR 13 MILES EAST OF
WALTON...MOVING SOUTHEAST AT 25 MPH.

THIS TORNADO WILL AFFECT MAINLY RURAL AREAS OF EASTERN LEE COUNTY...
INCLUDING THE FOLLOWING LOCATIONS WEST BROOKLYN AND COMPTON.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 4187 8927 4181 8894 4176 8894 4172 8897
      4163 8914 4179 8946
TIME...MOT...LOC 0212Z 298DEG 23KT 4175 8918

$$

RODRIGUEZ
289 
WWUS53 KLOT 030219
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
919 PM CDT TUE AUG 2 2011

ILC103-030229-
/O.CAN.KLOT.TO.W.0023.000000T0000Z-110803T0230Z/
LEE IL-
919 PM CDT TUE AUG 2 2011

...THE TORNADO WARNING FOR EASTERN LEE COUNTY IS CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED AND MOVED OUT OF
THE WARNED AREA...HOWEVER GUSTY WINDS ARE STILL POSSIBLE WITH THIS
THUNDERSTORM.

IN ADDITION...STRONG THUNDERSTORMS MAY REDEVELOP...AND A SEVERE
THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1 AM CDT.

LAT...LON 4187 8927 4181 8894 4176 8894 4172 8897
      4163 8914 4179 8946
TIME...MOT...LOC 0219Z 298DEG 23KT 4173 8913

$$

RODRIGUEZ

The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 2, 7:59 PM CDTSevere Thunderstorm WarningLOTDeKalb, Lee, Ogle, Winnebago61 min
Aug 2, 8:39 PM CDTSevere Thunderstorm WarningLOTBoone, Cook, DeKalb, DuPage, Kane, Lake and 1 more66 min
Aug 2, 8:54 PM CDTSpecial Marine WarningLOT2 hr
Aug 2, 9:11 PM CDTSevere Thunderstorm WarningLOTCook, DuPage64 min
Aug 2, 9:18 PM CDTSevere Thunderstorm WarningLOTCook, DuPage, Kane, Kendall, Will72 min
Aug 2, 9:33 PM CDTSevere Thunderstorm WarningLOTDeKalb, Grundy, Kendall, LaSalle, Lee57 min
Aug 2, 10:01 PM CDTSevere Thunderstorm WarningLOTGrundy, Kankakee, Kendall, LaSalle, Will59 min
Aug 2, 10:03 PM CDTAreal Flood AdvisoryLOTDeKalb, LaSalle, Lee4 hr
Aug 2, 10:07 PM CDTSevere Thunderstorm WarningLOTCook, Will68 min
Aug 2, 10:52 PM CDTSevere Thunderstorm WarningLOTIroquois, Kankakee, Will68 min
Aug 2, 11:15 PM CDTSevere Thunderstorm WarningLOTFord, Grundy, Iroquois, Kankakee, Livingston, Will41 min
Aug 3, 12:08 AM CDTSevere Thunderstorm WarningLOTIroquois52 min

Nearby

Tornado Warnings in Illinois, 2011Every tornado warning in 2011Tornadoes in 2011

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.