Alert archive / Illinois / Severe Thunderstorm Warnings in 2000

Severe Thunderstorm Warning 11, NWS Chicago, IL

April 20, 2000Grundy County, Kendall County, Will County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Apr 20, 2000, 5:45 AM CDT for Grundy County, Kendall County, Will County, Illinois. It was in force for 30 min. No storm report in the archive falls 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.

The facts

Issued: Apr 20, 2000, 5:45 AM CDT (10:45 UTC)
Expired: Apr 20, 2000, 6:15 AM CDT
In force: 30 min
Issued by: NWS Chicago, IL
Area: Whole counties; the outline is the Mesonet’s reconstruction

Counties Grundy County, IL, Kendall County, IL, Will County, IL

The radar

The Chicago radar (KLOT), 28 km from the middle of the area, began a volume at 10:47 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.

Issued	Product	Office	Lasted
Apr 20, 12:45 AM CDT	Severe Thunderstorm Watch	SPC	5 hr
Apr 20, 4:15 AM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 10.8 hours before the alert went out and 147 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1377 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 334 m²/s²
0-3 km storm-relative helicity: 489 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

000 
WUUS53 KLOT 201047
SVRCHI
ILC063-093-197-201115-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE CHICAGO IL
545 AM CDT THU APR 20 2000

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHERN GRUNDY COUNTY IN NORTHEAST ILLINOIS
  KENDALL COUNTY IN NORTHEAST ILLINOIS
  NORTHWEST WILL COUNTY IN NORTHEAST ILLINOIS

* UNTIL 615 AM CDT

* AT 545 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 5 MILES NORTHWEST OF MORRIS...MOVING NORTHEAST
  AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR
  MINOOKA AROUND 605 AM CDT
  CREST HILL AROUND 615 AM CDT

THE SEVERE THUNDERSTORM IS CAPABLE OF PRODUCING
  HAIL UP TO THE SIZE OF NICKELS.
  WINDS UP TO 60 MILES AN HOUR.
  VERY FREQUENT AND DEADLY CLOUD TO GROUND LIGHTNING.

STAY AWAY FROM WINDOWS.

LAT...LON 4146 8863 4130 8850 4133 8782 4172 8817

RATZER

NNNN

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at Apr 20, 3:30 AM CDT, 2 hours 15 minutes earlier.

Area forecast discussion, Apr 20, 3:30 AM CDT, 2 hours 15 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
330 AM CDT THU APR 20 2000

SCATTERED SEVERE CONVECTION BEGINING TO WIND DOWN THIS MORNING. 06Z
SURFACE ANALYSIS PLACES 970 MB LOW NEAR KANSAS CITY...WITH WARM
FRONT EXTENING EAST INTO CENTRAL ILLINOIS. STATIONARY FRONT
STRETCHES FROM NORTHERN ILLINOIS EAST ALONG THE INDIANA/MICHIGAN
BORDER. FORECAST CONCERNS CONTINUE TO BE PRECIPITATION TRENDS AS
SYSTEM WORKS ITS WAY EAST TODAY AND TONIGHT.

FOR THE SHORT TERM...CONVECTIVE THREAT TO CONTINUE THIS MORNING
AHEAD OF SPEED MAX LIFTING NORTHEAST ALONG SOUTHERN FLANK OF UPPER
SYSTEM. GOOD UPPER DIVERGENCE NOTED IN NUMERICAL MODEL FORECASTS
THIS MORNING.

MODELS ARE VERY SIMILAR IN MOVEMENT OF BOTH UPPER AND SURFACE LOWS.
SURFACE LOW PROGGED TO MOVE INTO CENTRAL ILLINOIS TODAY...AND THEN
INTO INDIANA OVERNIGHT. RAIN AND THUNDERSTORMS TO CONTINUE TODAY AS
UPPER SYSTEM MOVES IN...WITH SOME COUPLING OF JET MAXES SEEN IN
ISOTACH AND UPPER DIVERGENCE FIELDS.

PRECIPITATION ENDS TONIGHT FROM WEST TO EAST TONIGHT...WITH PRECIP
LIKELY OUT OF THE ROCKFORD AREA BY 12Z FRIDAY...AND OUT OF THE
EASTERN PORTIONS OF THE FORECAST AREA DURING THE MORNING. CURRENT
FORECAST HAS THESE TRENDS WELL IN HAND...AND FORESEE NO MAJOR
CHANGES. LATE TONIGHT AND FRIDAY LIKLEY TO BE WINDY DAY...IN TIGHT
CYCLONIC GRADIENT ON BACK SIDE OF DEPARTING SYSTEM. FWC SHOWING
SUSTAINED SPEEDS INTO THE 30 MPH RANGE...SO WILL BEEF UP WIND
WORDING. DAY SHIFT CAN DECIDE IF A WIND ADVISORY IS WARRANTED.

NEW MRF NOT IN YET...BUT DRY AND WARMER STILL LOOKS REASONABLE FOR
EXTENDED.

.CHI...GALE WRNG LK MI

RATZER

In the hours before

Local storm report, Apr 20, 5:20 AM CDT, 25 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO, IL
520 AM CDT THU APR 20 2000

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1125 PM    HARMON                  IL     7/8 INCH HAIL
04/19/00   LEE                            TRAINED STORM SPOTTER

0125 AM    SAUNEMIN 1NE            IL     3/4 INCH HAIL
04/20/00   LIVINGSTON                     LAW ENFORCEMENT

SMITTY

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, 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
Apr 20, 10:09 AM CDT	Tornado Warning	LOT	Iroquois	36 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2000 Every severe thunderstorm warning 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; radar from the NEXRAD Level II archive.