Alert archive / Illinois / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 101, NWS Chicago, IL

July 18, 1997Winnebago County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jul 18, 1997, 2:25 PM CDT for Winnebago County, Illinois. It was in force for 50 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Jul 18, 1997, 2:25 PM CDT (19:25 UTC)
Expired: Jul 18, 1997, 3:15 PM CDT
In force: 50 min
Issued by: NWS Chicago, IL
Area: Whole counties

County Winnebago County, IL

The radar

The Milwaukee radar (KMKX), 86 km from the middle of the area, began a volume at 19:24 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
Jul 18, 2:40 PM CDT	Thunderstorm Wind 52	Rockford, 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
Jul 18, 10:30 AM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 7.4 hours before the alert went out and 136 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: 1902 J/kg
Mixed-layer CIN: -83 J/kg
Mixed-layer LCL: 1153 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 4 m²/s²
0-3 km storm-relative helicity: 42 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 
TTAA00 KCHI 181923 RRA
SVRCHI
ILC201-182030-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE CHICAGO IL
225 PM CDT FRI JUL 18 1997
 
THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL  315 PM CDT
FOR PEOPLE IN THE FOLLOWING LOCATION...
 
IN NORTH CENTRAL ILLINOIS
 
   ...WINNEBAGO COUNTY
 
AT 222 PM RADAR INDICATED A SEVERE THUNDERSTORM NEAR DURAND. THE STORM
WAS MOVING EAST-SOUTHEAST AT 20 MPH AND WILL AFFECT ROCKFORD AND
MACHESNEY PARK.
 
 
THIS IS A DANGEROUS STORM!  STAY INDOORS...AWAY FROM WINDOWS!

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.

In the hours before

Local storm report, Jul 18, 8:35 AM CDT, 5 hours 50 minutes before

PRELIMINARY LOCAL STORM REPORT...CORRECT ISSUED AM FROM PM
NATIONAL WEATHER SERVICE CHICAGO IL
835 AM CDT FRI JUL 18 1997

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

0710 AM    WAYNE                     IL   WIND DAMAGE
07/18/97   DU PAGE                        TREES DOWN
                                          IL59 & ARMY TRAIL RD.

0725 AM    CAROL STREAM              IL   WIND GUST
07/18/97   DU PAGE                        63 MPH MEASURED

Local storm report, Jul 18, 8:38 AM CDT, 5 hours 47 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
835 PM CDT FRI JUL 18 1997

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

0710 AM    WAYNE                     IL   WIND DAMAGE
07/18/97   DU PAGE                        TREES DOWN
                                          IL59 & ARMY TRAIL RD.
0725 AM    CAROL STREAM              IL   63 MPH WIND GUST
07/18/97   DUPAGE                         MEASURED

Local storm report, Jul 18, 9:16 AM CDT, 5 hours 9 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
835 PM CDT FRI JUL 18 1997

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

0710 AM    WAYNE                     IL   WIND DAMAGE
07/18/97   DU PAGE                        TREES DOWN
                                          IL59 & ARMY TRAIL RD.

0725 AM    CAROL STREAM              IL   WIND GUST
07/18/97   DU PAGE                        63 MPH MEASURED

Special weather statement, Jul 18, 10:57 AM CDT, 3 hours 28 minutes before

ILZ003>006-008-010>014-019>023-032>033-039-INZ001>005-010>016-019>020-
191100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO IL
1100 AM CDT FRI JUL 19 1997

FOR NORTH CENTRAL AND NORTHEAST ILLINOIS AND NORTHWEST AND NORTH
CENTRAL INDIANA

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN NORTH CENTRAL AND
NORTHEAST ILLINOIS AND A SMALL PART OF NORTHWEST INDIANA THIS
AFTERNOON AND TONIGHT. NO SEVERE STORMS ARE EXPECTED IN NORTH CENTRAL
INDIANA.

AFTERNOON TEMPERATURES OF 85 TO 90 COMBINED WITH DEWPOINT TEMPERATURES
IN THE LOWER TO MIDDLE 70S WILL CREATE A VERY WARM...HUMID...UNSTABLE
ATMOSPHERE OVER NORTHERN ILLINOIS AND INDIANA. A COLD FRONT PUSHING
SOUTH FROM WISCONSIN AND MICHIGAN WILL REACH NORTHERN ILLINOIS AND
INDIANA TOWARD EVENING. THIS WILL BE THE FOCUS OF THUNDERSTORM ACTIVITY.
A STRONG JET STREAM ACROSS THE NORTHERN GREAT LAKES WILL ENHANCE THE
THUNDERSTORM DEVELOPMENT.

A COMPLEX OF STRONG THUNDERSTORMS WAS OVER SOUTHEAST MINNESOTA LATE
THIS MORNING. IT IS EXPECTED TO CONTINUE TO PROPOGATE EAST SOUTHEAST
TOWARD NORTHWEST AND NORTH CENTRAL ILLINOIS THIS AFTERNOON. A SEVERE
THUNDERSTORM WATCH IS IN EFFECT FOR NORTHWEST AND NORTH CENTRAL
ILLINOIS UNTILr 400 PM.

ALLSOPP

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 18, 1:12 PM CDT	Severe Thunderstorm Warning	LOT	Cook	63 min
Jul 18, 2:39 PM CDT	Severe Thunderstorm Warning	LOT	Lake, McHenry	66 min
Jul 18, 2:42 PM CDT	Severe Thunderstorm Warning	LOT	LaSalle	48 min
Jul 18, 2:42 PM CDT	Severe Thunderstorm Warning	LOT	Boone	48 min
Jul 18, 2:52 PM CDT	Severe Thunderstorm Warning	LOT	Cook	53 min
Jul 18, 3:05 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Lee	55 min
Jul 18, 3:07 PM CDT	Severe Thunderstorm Warning	LOT	Kankakee, Will	68 min
Jul 18, 3:29 PM CDT	Severe Thunderstorm Warning	LOT	DuPage, Kane, Kendall	61 min
Jul 18, 3:37 PM CDT	Severe Thunderstorm Warning	LOT	Cook, Will	68 min
Jul 18, 3:57 PM CDT	Severe Thunderstorm Warning	LOT	Grundy, Will	63 min
Jul 18, 4:07 PM CDT	Severe Thunderstorm Warning	LOT	Kankakee	68 min
Jul 18, 4:47 PM CDT	Severe Thunderstorm Warning	LOT	Iroquois	58 min

Nearby

Severe Thunderstorm Warnings in Illinois, 1997 Every severe thunderstorm warning in 1997

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.