Alert archive / Illinois / Tornado Warnings in 2000

Tornado Warning 1, NWS Chicago, IL

April 20, 2000Iroquois County, Illinois

NWS Chicago, IL issued this tornado warning at Apr 20, 2000, 10:09 AM CDT for Iroquois County, Illinois. It was in force for 36 min. 1 report came from inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties, with what was reported inside it.

The facts

Issued: Apr 20, 2000, 10:09 AM CDT (15:09 UTC)
Expired: Apr 20, 2000, 10:45 AM CDT
In force: 36 min
Issued by: NWS Chicago, IL
Area: Whole counties; the outline is the Mesonet’s reconstruction

County Iroquois County, IL

The radar

The Chicago radar (KLOT), 102 km from the middle of the area, began a volume at 15:07 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.

What was reported inside it

Time	Report	Where	Remark
Apr 20, 10:30 AM CDT	Hail 1	Woodland, IL

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The watch it was issued in

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

Issued	Product	Office	Lasted
Apr 20, 10:00 AM CDT	Tornado Watch	SPC	6 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 3.2 hours before the alert went out and 96 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: 595 J/kg
Mixed-layer CIN: -48 J/kg
Mixed-layer LCL: 873 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 167 m²/s²
0-3 km storm-relative helicity: 147 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 3.4

Open this sounding in Storm Lab

The text

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

000 
WFUS53 KLOT 201510
TORCHI
ILC075-201545-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CHICAGO IL
1009 AM CDT THU APR 20 2000

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* TORNADO WARNING FOR...
  IROQUOIS COUNTY IN EAST CENTRAL ILLINOIS

* UNTIL 1045 AM CDT

* AT 1009 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM WITH STRONG ROTATION 5 MILES SOUTHWEST OF
  WOODLAND...OR ABOUT 8 MILES SOUTHWEST OF WATSEKA...MOVING NORTHEAST
  AT 50 MPH. THIS STORM COULD PRODUCE A TORNADO AT ANY TIME.

* THE POTENTIALLY TORNADIC THUNDERSTORM WILL BE NEAR
  WATSEKA AROUND 1015 AM CDT
  IROQUOIS AROUND 1025 AM CDT
  DONOVAN AROUND 1030 AM CDT

THIS IS A DANGEROUS STORM. MOVE INTO YOUR TORNADO SHELTER NOW!

LAT...LON 4069 8795 4056 8779 4070 8755 4099 8753

NNNN

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 20, 12:11 AM CDT	Severe Thunderstorm Warning	LOT	Boone, Winnebago	34 min
Apr 20, 1:22 AM CDT	Severe Thunderstorm Warning	LOT	Ford, Livingston	38 min
Apr 20, 1:40 AM CDT	Severe Thunderstorm Warning	LOT	Kankakee	35 min
Apr 20, 2:14 AM CDT	Severe Thunderstorm Warning	LOT	Kankakee	31 min
Apr 20, 5:45 AM CDT	Severe Thunderstorm Warning	LOT	Grundy, Kendall, Will	30 min
Apr 20, 6:30 AM CDT	Severe Thunderstorm Warning	LOT	Grundy, LaSalle, Livingston	45 min
Apr 20, 6:42 AM CDT	Severe Thunderstorm Warning	LOT	Ford	33 min
Apr 20, 7:00 AM CDT	Severe Thunderstorm Warning	LOT	Kendall, Will	60 min
Apr 20, 7:00 AM CDT	Severe Thunderstorm Warning	LOT	Iroquois, Kankakee	60 min
Apr 20, 7:37 AM CDT	Severe Thunderstorm Warning	LOT	Cook	51 min
Apr 20, 7:37 AM CDT	Severe Thunderstorm Warning	LOT	DuPage, Kane	51 min
Apr 20, 9:51 AM CDT	Severe Thunderstorm Warning	LOT	Ford, Livingston	39 min
Apr 20, 9:51 AM CDT	Severe Thunderstorm Warning	LOT	Iroquois	39 min

Nearby

Tornado Warnings in Illinois, 2000 Every tornado warning in 2000 Tornadoes 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.