Alert archive / Indiana / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 57, NWS Chicago, IL

August 18, 2001Iroquois County, Illinois; Benton County, Newton County, Indiana

NWS Chicago, IL issued this severe thunderstorm warning at Aug 18, 2001, 2:03 PM CDT for Iroquois County, Illinois; Benton County, Newton County, Indiana. It was in force for 27 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
Aug 18, 2001, 2:03 PM CDT (19:03 UTC)
Expired
Aug 18, 2001, 2:30 PM CDT
In force
27 min
Issued by
NWS Chicago, IL
Area
Whole counties

Counties Iroquois County, IL, Benton County, IN, Newton County, IN

The radar

The Chicago radar (KLOT), 105 km from the middle of the area, began a volume at 19:05 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

TimeReportWhereRemark
Aug 18, 2:25 PM CDTHail 4Countywide, INA slow moving thunderstorm moved from east central Illinois into Benton county during the afternoon of August 18th. This thunderstorm produced hail to the size of grapefruit 3 miles north of Otterbein, where several windows and a roof of a house were damaged.

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.

IssuedProductOfficeLasted
Aug 18, 12:30 PM CDTTornado WatchSPC6 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 7.1 hours before the alert went out and 115 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, Lincoln, IL at 12:00Z on 2001-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 192 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 12:00Z on 2001-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 92 square meters per square second.19395878Sfc1 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
192 J/kg
Mixed-layer CIN
-146 J/kg
Mixed-layer LCL
1002 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
92 m²/s²
0-3 km storm-relative helicity
136 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

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 Aug 18, 3:34 AM CDT, 10 hours 29 minutes earlier.

Area forecast discussion, Aug 18, 3:34 AM CDT, 10 hours 29 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
300 AM CDT SAT AUG 18 2001

THE 500 MB TROUGH OVER MINNESOTA AND IOWA HAS COLD ADVECTION AT LOW
LEVELS AND A JET STREAK OVER THE DAKOTAS JUST TO THE WEST. THE
TROUGH SHOULD DEEPEN SOME MORE AS IT MOVES EAST. THE LAYER BETWEEN
800 AND 600 MB IS VERY DRY AS SEEN ON THE ILX SOUNDING. RADAR SHOWS
SHOWERS AND THUNDERSTORMS MOVING INTO EASTERN IOWA AND WESTERN
WISCONSIN.

THERE WAS POSITIVE MOISTURE ADVECTION AT 700 MB AT 00 UTC. THIS
ADVECTION WAS OVER IOWA AND BEGINNING TO MOVE INTO NORTHWEST
ILLINOIS. SURFACE DEWPOINTS AND WIND ANALYSIS SHOWS MOISTURE
ADVECTION AT THE SURFACE. INCREASE IN MOISTURE WILL CONTINUE THROUGH
THE EARLY MORNING. WILL KEEP LIKELY POPS IN THE FORECAST. USING THE
ACARS SOUNDINGS AND ADJUSTING THEM FOR CHANGES. FIND THAT THE
ATMOSPHERE BECOMES UNSTABLE LATER TODAY.

WILL USE GUIDANCE AND WILL STAY CLOSE TO GUIDANCE FOR THE FORECAST
HIGHS AND LOWS.

.CHI...NONE.

WHW

In the hours before

Special weather statement, Aug 18, 12:14 PM CDT, 1 hour 49 minutes before
ILZ003>006-008-010>014-019>023-032>033-039-INZ001>002-010>011-019-
191100-

SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO IL
1200 PM CDT/EST SAT AUG 18 2001

FOR NORTH CENTRAL AND NORTHEAST ILLINOIS AND NORTHWEST INDIANA

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EARLY EVENING FOR NORTHWEST INDIANA AND EAST CENTRAL ILLINOIS. THE
THREAT AREA INCLUDES AREAS EAST AND SOUTH OF A LINE FROM ABOUT
MICHIGAN CITY INDIANA TO KANKAKEE ILLINOIS TO PONTIAC ILLINOIS.

THERE IS SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EARLY THIS EVENING FOR NORTHEAST AND NORTH CENTRAL ILLINOIS
INCLUDING CHICAGO AND ROCKFORD.

A DEVELOPING LOW IN WEST CENTRAL ILLINOIS IS EXPECTED TO STRENGTH
THIS AFTERNOON. THE LOW WILL MOVE ACROSS AN AREA OF INCREASINGLY
UNSTABLE AIR AND HELP PRODUCE STRONG TO SEVERE
THUNDERSTORMS...ESPECIALLY IN THE MODERATE RISK AREA. THE THREATS
FROM THE STORMS WILL BE LARGE HAIL...DAMAGING WINDS...AND SOME
TORNADOES.

BE ALERT FOR THREATENING WEATHER CONDITIONS THIS AFTERNOON. STAY
TUNED TO WEATHER RADIO OR YOU FAVORITE TV OR RADIO STATION FOR
DEVELOPING WEATHER INFORMATION THROUGHOUT THE AFTERNOON

SOMREK
Local storm report, Aug 18, 1:46 PM CDT, 17 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
146 PM CDT SAT AUG 18 2001

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

0120 PM    2 W GIBSON CITY           IL   1 INCH HAIL
08/18/01   FORD                           REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.

0140 PM    1 NW GIBSON CITY          IL   1.25 INCH HAIL
08/18/01   FORD                           REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 18, 12:53 PM CDTSevere Thunderstorm WarningLOTFord, Iroquois37 min
Aug 18, 12:53 PM CDTSevere Thunderstorm WarningLOTLivingston37 min
Aug 18, 1:26 PM CDTSevere Thunderstorm WarningLOTFord, Livingston64 min
Aug 18, 2:48 PM CDTSevere Thunderstorm WarningLOTBenton27 min

Nearby

Severe Thunderstorm Warnings in Indiana, 2001Severe Thunderstorm Warnings in Illinois, 2001Every severe thunderstorm warning in 2001

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.