Alert archive / Illinois / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 31, NWS St. Louis, MO

April 18, 19974 counties in Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Apr 18, 1997, 11:17 PM CDT for 4 counties in Illinois. It was in force for 43 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: Apr 18, 1997, 11:17 PM CDT (04:17 UTC)
Expired: Apr 19, 1997, 12:00 AM CDT
In force: 43 min
Issued by: NWS St. Louis, MO
Area: Whole counties

Counties Greene County, IL, Jersey County, IL, Macoupin County, IL, Madison County, IL

The radar

The St Louis radar (KLSX), 67 km from the middle of the area, began a volume at 04:20 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 18, 11:20 PM CDT	Hail 0.88	Carrollton, 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 18, 9:15 PM CDT	Severe Thunderstorm Watch	SPC	4 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 4.3 hours before the alert went out and 174 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: 2539 m above ground
0-6 km bulk shear: 60 kt
0-1 km storm-relative helicity: 96 m²/s²
0-3 km storm-relative helicity: 257 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.

055 
WUUS1 KSTL 190419 RRA
SVRSTL
ILC117-061-083-119-190500-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
1117 PM CDT FRI APR 18 1997
 
THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL MIDNIGHT CDT
FOR PEOPLE IN THE FOLLOWING LOCATIONS...
 
IN CENTRAL ILLINOIS
 
   ...MACOUPIN COUNTY
 
IN SOUTHWEST ILLINOIS
 
   ...GREENE COUNTY...JERSEY COUNTY...MADISON COUNTY
 
AT 1117 PM CDT SEVERE THUNDERSTORMS WERE NEAR CARROLLTON AND
JERSEYVILLE MOVING SOUTHEAST AT 30 MPH.
 
TOWNS IN THE PATH INCLUDE KEMPER...MEDORA...BRIGHTON AND ALTON.
 
HAIL AROUND 1 INCH IN DIAMETER CAN BE EXPECTED WITH THESE STORMS.
 
JPK

The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 18, 8:51 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun	39 min
Apr 18, 8:58 PM CDT	Severe Thunderstorm Warning	LSX	Pike	47 min
Apr 18, 9:45 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun	45 min
Apr 18, 10:20 PM CDT	Severe Thunderstorm Warning	LSX	Madison, Saint Clair	40 min
Apr 18, 11:56 PM CDT	Severe Thunderstorm Warning	LSX	Jersey, Madison	49 min
Apr 19, 12:34 AM CDT	Severe Thunderstorm Warning	LSX	Clinton, Saint Clair, Washington	41 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.