Alert archive / Illinois / Tornado Warnings in 2004

Tornado Warning 18, NWS Chicago, IL

April 20, 2004DuPage County, Kane County, Kendall County, Illinois

NWS Chicago, IL issued this tornado warning at Apr 20, 2004, 8:12 PM CDT for DuPage County, Kane County, Kendall County, Illinois. It was in force for 33 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: Apr 20, 2004, 8:12 PM CDT (01:12 UTC)
Expired: Apr 20, 2004, 8:45 PM CDT
In force: 33 min
Issued by: NWS Chicago, IL
Area: Counties, with a storm outline in the text

Counties DuPage County, IL, Kane County, IL, Kendall County, IL

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this tornado warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 1.2 hours before the alert went out and 181 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 118 J/kg
Mixed-layer CIN: -27 J/kg
Mixed-layer LCL: 1737 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 176 m²/s²
0-3 km storm-relative helicity: 261 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.7

Open this sounding in Storm Lab

The text

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

000 
WFUS53 KLOT 210112
TORLOT
ILC043-089-093-210145-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CHICAGO IL
812 PM CDT TUE APR 20 2004

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* TORNADO WARNING FOR...
  DUPAGE COUNTY IN NORTHEAST ILLINOIS
  KANE COUNTY IN NORTHEAST ILLINOIS
  KENDALL COUNTY IN NORTHEAST ILLINOIS

* UNTIL 845 PM CDT

* AT 812 PM CDT...DOPPLER RADAR INDICATED STRONG ROTATION IN A SEVERE
  THUNDERSTORM NEAR 5 MILES SOUTHWEST OF OSWEGO...MOVING NORTHEAST AT
  25 MPH.

* A FUNNEL CLOUD WAS REPORTED NEAR SANDWICH AND SHABBONA ROADS IN    
  NORTHERN KENDALL COUNTY.

* THE STORM WILL BE NEAR...
  MONTGOMERY AROUND 820 PM CDT.
  AURORA AROUND 825 PM CDT.
  NAPERVILLE AROUND 835 PM CDT.
  WARRENVILLE AROUND 840 PM CDT.
  LISLE AROUND 845 PM CDT.

DO NOT WAIT UNTIL YOU HEAR OR SEE THE TORNADO. TAKE SHELTER NOW.
REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCEMENT AGENCY. THEY
WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE.

LAT...LON 4185 8808 4178 8800 4174 8804 4173 8821
          4164 8828 4160 8835 4167 8843 4174 8842
          4194 8817
$$

BRUMER

NNNN

What forecasters said that day

The local office's own words before this tornado warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Chicago, IL wrote its last area forecast discussion before this tornado warning went out at Apr 20, 2:50 PM CDT, 5 hours 22 minutes earlier.

Area forecast discussion, Apr 20, 2:50 PM CDT, 5 hours 22 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
250 PM CDT TUE APR 20 2004

.DISCUSSION...
ISENTROPICALLY INDUCED LIFT YIELDING RA WITH EMBEDDED LOW-
TOPPED, MOIST CONVECTION WILL BE ONGOING AT ZONE ISSUANCE TIME.
SFC WARM FRONT WILL PROPAGATE RAPIDLY NORTHWARD THIS EVENING.
THEREFORE, TEMPS ARE EXPECTED TO WARM OVERNIGHT WITH OCCASIONAL
TSRA/SHRA WITHIN THE WARM SECTOR. FOR TOMORROW...MILD HIGH TEMPS
SHOULD OCCUR BY 18Z WITH TEMPS FALLING IN THE AFTERNOON BEHIND
COLD FROPA. KEPT LOW CHANCE POPS ACROSS THE CWA WITH AFTERNOON
TSRA OVER THE IN ZONES.

AGREE WITH HPC CONCERNING THE GFS BEING TOO FAR NORTH WITH QPF
FOR THR AND THR NIGHT...HAVE GONE WITH A DRY FCST FOR THESE
PERIODS. I HAVE INTRODUCED POPS BEGINNING FRI NIGHT INTO SATURDAY
AS A STRONG S/WV TROUGH MOVES ACROSS THE PLAINS AND OVER THE
REGION. AS OF NOW THE CWA WOULD LIE TO THE NORTH OF THE SFC
LOW KEEPING THE REGION COOL FOR THE WEEKEND. ALL IN ALL, FEW
CHANGES WERE NEEDED TO THE INHERITED FCST AND IN GOOD ISC AND
NWP AGREEMENT.

05

&&

.AVIATION DISCUSSION REGARDING 18Z TAFS:
BAND OF SHOWERS RAPIDLY MOVING INTO TAF SITES AT 18Z. LTG FOR
TIME HAS ALL DROPPED OUT. DECIDED NOT TO CARRY ANY TS FOR
AFTERNOON. COULD BE A FEW REFIRE BUT FEW AND FAR BETWEEN AND JUST
A FLASH OR TWO. NO BIG DEAL. CONDS BECOMING MVFR CIGS/VIS AS SHRA
MOVE INTO DURING AFTERNOON AND AHEAD OF WRMFRONT. FROPA 02-04Z.
BEST  CHANCE TS AGAIN AROUND 06-08Z AS BEST DYNAMICS COME INTO
PLAY AND WE WILL BE IN UNSTABLE WARM SECTOR. CLOUDS TO SCATTER
OUT DURING TOMORROW MORNING.
AF

&&

.LOT...WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LK MI...NONE.

Hazardous weather outlook, Apr 20, 7:10 PM CDT, 1 hour 2 minutes before

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE CHICAGO IL
710 PM CDT TUE APR 20 2004

ILZ003>006-008-010>014-019>022-023-032-033-039-INZ001-002-010-011-
019-211100-
WINNEBAGO-BOONE-MCHENRY-LAKE IL-OGLE-LEE-DE KALB-KANE-DU PAGE-
COOK-LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON-
IROQUOIS-FORD-LAKE IN-PORTER-NEWTON-JASPER-BENTON-
710 PM CDT TUE APR 20 2004

THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR NORTH
CENTRAL AND NORTHEAST ILLINOIS...AND NORTHWEST INDIANA.

.DAY ONE... TONIGHT

A TORNADO WATCH IS IN EFFECT UNTIL 11 PM CDT FOR ALL COUNTIES...
EXCEPT OGLE...WINNEBAGO...BOONE...MCHENRY AND LAKE COUNTY IN
ILLINOIS. SEVERE THUNDERSTORMS MAY PRODUCE LARGE HAIL...DAMAGING
WINDS AND ISOLATED TORNADOES. THE SEVERE WEATHER THREAT WILL
DIMINISH AFTER 11 PM CDT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTHWEST INDIANA
WEDNESDAY AFTERNOON. THIS AREA IS GENERALLY EAST OF A GARY TO
CHAMPAIGN LINE AND ASSOCIATED WITH THE CONTINUED EAST MOVING COLD
FRONT.

THERE IS ANOTHER CHANCE OF THUNDERSTORMS IN NORTHWEST INDIANA
SATURDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE NEEDED THROUGH 11 PM.

&&

NWS CHICAGO WEBPAGE: WWW.CRH.NOAA.GOV/LOT (LOWER CASE)

LMZ740>746-766-211100-
WINTHROP HARBOR TO WILMETTE HARBOR-WILMETTE HARBOR TO NORTHERLY
ISLAND-NORTHERLY ISLAND TO CALUMET HARBOR-CALUMET HARBOR TO GARY-
GARY TO BURNS HARBOR-BURNS HARBOR TO MICHIGAN CITY-MICHIGAN CITY TO
NEW BUFFALO-
710 PM CDT TUE APR 20 2004

THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS
AND INDIANA WATERS OF LAKE MICHIGAN.

.DAY ONE... TONIGHT

A TORNADO WATCH IS IN EFFECT UNTIL 11 PM CDT FOR THE FAR SOUTHERN
PORTION OF LAKE MICHIGAN. SEVERE THUNDERSTORMS MAY PRODUCE LARGE
HAIL...DAMAGING WINDS AND ISOLATED WATERSPOUTS. THE SEVERE WEATHER
THREAT WILL DIMINISH AFTER 11 PM CDT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

A SMALL CRAFT ADVISORY MAY BE NEEDED WEDNESDAY.

&&

NWS CHICAGO WEBPAGE: WWW.CRH.NOAA.GOV/LOT (LOWER CASE)

In the hours before

Local storm report, Apr 20, 7:44 PM CDT, 28 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
744 PM CDT TUE APR 20 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0743 PM     TORNADO          KANKAKEE                41.12N 87.86W
04/20/2004                   KANKAKEE           IL   TRAINED SPOTTER

            TORNADO REPORTED NEAR AIRPORT CROSSING INTERSTATE 57
            MOVING EAST.

&&

Local storm report, Apr 20, 7:46 PM CDT, 26 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
746 PM CDT TUE APR 20 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0740 PM     HAIL             BRADLEY                 41.15N 87.86W
04/20/2004  1.75 INCH        KANKAKEE           IL   TRAINED SPOTTER

            STRONG ROTATION NOTED IN CLOUDS.

&&

Local storm report, Apr 20, 7:58 PM CDT, 14 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
758 PM CDT TUE APR 20 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0738 PM     TORNADO          4 E KANKAKEE            41.12N 87.78W
04/20/2004                   KANKAKEE           IL   TRAINED SPOTTER

            AT INTERSECTION OF 4000E AND EXLINE ROAD. DAMAGE TO HOUSE
            AND FACTORY WITH DOWNED POWER LINES.

&&

Local storm report, Apr 20, 8:02 PM CDT, 10 minutes before

PRELIMINARY LOCAL STORM REPORT ... SUMMARY
NATIONAL WEATHER SERVICE CHICAGO IL
802 PM CDT TUE APR 20 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0743 PM     TORNADO          KANKAKEE                41.12N 87.86W
04/20/2004                   KANKAKEE           IL   TRAINED SPOTTER

            TORNADO REPORTED NEAR AIRPORT CROSSING INTERSTATE 57
            MOVING EAST.

0740 PM     HAIL             BRADLEY                 41.15N 87.86W
04/20/2004  1.75 INCH        KANKAKEE           IL   TRAINED SPOTTER

            STRONG ROTATION NOTED IN CLOUDS.

0738 PM     TORNADO          4 E KANKAKEE            41.12N 87.78W
04/20/2004                   KANKAKEE           IL   TRAINED SPOTTER

            AT INTERSECTION OF 4000E AND EXLINE ROAD. DAMAGE TO HOUSE
            AND FACTORY WITH DOWNED POWER LINES.

0727 PM     TORNADO          CHANNAHON               41.43N 88.22W
04/20/2004                   WILL               IL   TRAINED SPOTTER

            REPORTED ON GROUND IN CITY.

0725 PM     TORNADO          SHERIDAN                41.53N 88.69W
04/20/2004                   LA SALLE           IL   TRAINED SPOTTER

            LIGHT DAMAGE REPORTED.

0724 PM     TORNADO          7 NW GILMAN             40.84N 88.09W
04/20/2004                   IROQUOIS           IL   TRAINED SPOTTER

0705 PM     TORNADO          2 WNW PAXTON            40.47N 88.13W
04/20/2004                   FORD               IL   LAW ENFORCEMENT

            ON FORD AND IROQUOIS COUNTY LINE NORTH OF STATE HIGHWAY
            116

0705 PM     TORNADO          2 WNW PAXTON            40.47N 88.13W
04/20/2004                   FORD               IL   LAW ENFORCEMENT

            ON FORD IROQUOIS COUNTY LINES NORTH OF STATE HWY 116

0705 PM     TORNADO          LA SALLE                41.34N 89.09W
04/20/2004                   LA SALLE           IL   AMATEUR RADIO

            DAMAGE REPORT 1 BUILDING COLLAPSED. MAJOR DAMAGE WITH
            PEOPLE TRAPPED

0652 PM     TORNADO          5 NE SENECA             41.35N 88.55W
04/20/2004                   GRUNDY             IL   TRAINED SPOTTER

            2 TORNADOS NEAR STATE HWY 52.

0648 PM     TORNADO          3 NE OTTAWA             41.38N 88.80W
04/20/2004                   LA SALLE           IL   TRAINED SPOTTER

            SOUTH OF SERENA ON ILLINOIS ROUTE 52

0620 PM     TORNADO          9 W OTTAWA              41.35N 89.01W
04/20/2004                   LA SALLE           IL   TRAINED SPOTTER

            TONADO WITH MULTIPLE VORTEX MOVING NORTHEAST.

0612 PM     TORNADO          LA SALLE                41.34N 89.09W
04/20/2004                   LA SALLE           IL   LAW ENFORCEMENT

            INTERSTATE 80 MILE MARKER 75

0609 PM     TORNADO          8 E PERU                41.34N 88.97W
04/20/2004                   LA SALLE           IL   TRAINED SPOTTER

            TORNADO IN COMMUNITY OF UTTICA MOVING EAST.

0603 PM     TORNADO          OGLESBY                 41.29N 89.06W
04/20/2004                   LA SALLE           IL   FIRE DEPT/RESCUE

0603 PM     HAIL             PERU                    41.34N 89.13W
04/20/2004  0.25 INCH        LA SALLE           IL   NWS EMPLOYEE

0601 PM     TORNADO          OGLESBY                 41.29N 89.06W
04/20/2004                   LA SALLE           IL   AMATEUR RADIO

0558 PM     TORNADO          3 NE LA SALLE           41.37N 89.05W
04/20/2004                   LA SALLE           IL   LAW ENFORCEMENT

&&

Local storm report, Apr 20, 8:08 PM CDT, 4 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
808 PM CDT TUE APR 20 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0806 PM     TORNADO          7 NE OTTAWA             41.42N 88.74W
04/20/2004                   LA SALLE           IL   TRAINED SPOTTER

            REPORTED IN NORWAY SUBDIVISION AT INTERSECTION OF ROUTE
            52 AND STATE HWY 71 MOVING E.

&&

Local storm report, Apr 20, 8:10 PM CDT, 2 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
810 PM CDT TUE APR 20 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0756 PM     HAIL             JOLIET                  41.53N 88.12W
04/20/2004  1.75 INCH        WILL               IL   PUBLIC

            VEHICLES DAMAGED.

&&

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 20, 7:01 PM CDT	Tornado Warning	LOT	Grundy, Will	29 min
Apr 20, 7:13 PM CDT	Tornado Warning	LOT	Kankakee	32 min
Apr 20, 7:15 PM CDT	Tornado Warning	LOT	Iroquois	30 min
Apr 20, 7:17 PM CDT	Tornado Warning	LOT	Livingston	43 min
Apr 20, 7:17 PM CDT	Tornado Warning	LOT	DuPage, Kane, Kendall	28 min
Apr 20, 7:21 PM CDT	Tornado Warning	LOT	LaSalle	24 min
Apr 20, 7:31 PM CDT	Tornado Warning	LOT	Will	29 min
Apr 20, 7:34 PM CDT	Tornado Warning	LOT	Grundy	41 min
Apr 20, 7:44 PM CDT	Tornado Warning	LOT	Kendall	31 min
Apr 20, 7:44 PM CDT	Tornado Warning	LOT	Kankakee	46 min
Apr 20, 7:47 PM CDT	Tornado Warning	LOT	Kendall	28 min
Apr 20, 7:53 PM CDT	Special Marine Warning	LOT		82 min
Apr 20, 7:53 PM CDT	Special Marine Warning	LOT		82 min
Apr 20, 7:53 PM CDT	Special Marine Warning	LOT		82 min
Apr 20, 8:02 PM CDT	Tornado Warning	LOT	Cook, Will	28 min
Apr 20, 8:03 PM CDT	Flash Flood Warning	LOT	Cook, Will	3 hr
Apr 20, 8:27 PM CDT	Tornado Warning	LOT	Cook, Will	48 min
Apr 20, 9:11 PM CDT	Severe Thunderstorm Warning	LOT	Cook	49 min
Apr 20, 9:16 PM CDT	Special Marine Warning	LOT		89 min
Apr 20, 9:16 PM CDT	Special Marine Warning	LOT		89 min
Apr 20, 9:16 PM CDT	Special Marine Warning	LOT		89 min

Nearby

Tornado Warnings in Illinois, 2004 Every tornado warning in 2004 Tornadoes in 2004

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.