Alert archive / Illinois / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 217, NWS St. Louis, MO

August 19, 1999Macoupin County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Aug 19, 1999, 12:54 AM CDT for Macoupin County, Illinois. It was in force for 66 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 19, 1999, 12:54 AM CDT (05:54 UTC)
Expired
Aug 19, 1999, 2:00 AM CDT
In force
66 min
Issued by
NWS St. Louis, MO
Area
Whole counties

County Macoupin County, IL

The radar

The St Louis radar (KLSX), 91 km from the middle of the area, began a volume at 05:56 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 19, 1:10 AM CDTHail 0.75Palmyra, 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 nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 5.9 hours before the alert went out and 150 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 00:00Z on 1999-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1 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 00:00Z on 1999-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 172 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
1 J/kg
Mixed-layer CIN
-167 J/kg
Mixed-layer LCL
1415 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
172 m²/s²
0-3 km storm-relative helicity
274 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KSTL 190555 RRA
SVRSTL
ILC117-190700-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
1254 AM CDT THU AUG 19 1999

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHERN MACOUPIN COUNTY IN SOUTHWESTERN ILLINOIS

* UNTIL 200 AM CDT

* AT 1255 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  A SEVERE THUNDERSTORM IN THE NORTHEAST CORNER OF GREENE COUNTY
  NEAR ATHENSVILLE... MOVING SOUTHEAST AT 35 MPH.

* LOCATIONS THAT WILL BE AFFECTED...
  SCOTTVILLE
  MODESTO
  PALMYRA
  CARLINVILLE

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND GUSTS IN EXCESS OF 60
MPH...DAMAGING HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. MOVE
TO AN INTERIOR ROOM ON THE LOWEST FLOOR OR YOUR HOME OR BUSINESS.
HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO AREAS WHERE
WATER COVERS THE ROAD.

JP

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 St. Louis, MO wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 18, 3:35 PM CDT, 9 hours 19 minutes earlier.

Area forecast discussion, Aug 18, 3:35 PM CDT, 9 hours 19 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
335 PM CDT WED AUG 18 1999

BIG-TIME WRMFNT FROM JUST SW OF COU TO JUST N OF FAM IS TRYING TO
PRIME THE PUMP FOR CNVTN AS WE HEAD INTO THE EVENING HRS.  SUSTAINED
MSTR CNVGC OVR N MO AS WELL AS STG HTG SW OF FNTL BNDRY ERYR THIS
AFTN WAS WKNG CAP.  HWVR...PREFNTL TROF APRS TO BE WKNG CNVGC SM OVR
AREA LAST 1-2 HRS.  EVEN THO NOT TOO MUCH IN THE WAY OF DYNAMICS...
STILL THINK LO LVL FORCING SHUD BE ENUF TO INITIATE CNVTN NXT FEW
HRS...WITH INSTABILITY THEN FUELING THE STMS THRUOUT THE EVENING HRS
ALG/AHD OF FNTL BNDRYS.

SCND SHTWV SHOWING UP OVR NW WI WL BE DROPPING SWD DURG THE NEXT 24
HRS AS HGTS CONT TO FALL OVR E THIRD OF THE COUNTRY.  UVV WITH THIS
FTR SHUD GIVE AREAS ALG-E OF MS RVR ANOTHER CHC OF PCPN LT TNGT AND
INTO THU...WHILE SHIFT IN UA PTRN WL GIVE AREA COOLER THAN NORMAL
DAYTIME TEMPS FOR THE LAST PART OF THIS WK MUCH AS SUGGESTED BY
CURRENT FCST TRENDS.  GIVEN XTNSV CLD/TEMPS TRENDS UPSTREAM THIS
AFTN...CERTAINLY APRS THAT FWC HAS TOO FEW CLDS AND ARE TOO WRM WITH
TEMPS ON THU...AND PROB FRIDAY AS WELL.  AGAIN...GOING ZNS LEANING
TWD COOLER TEMPS AND THINK THIS STILL LKS QUITE GD.
HISTORICALLY...THE LWR GUID TEMPS HV BEEN MORE CORRECT OVR MS VLY
THE LAST SVRL TIMES COOLER AIR HAS INVADED AREA.

.STL...NONE
TRUETT

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 18, 11:13 PM CDTSevere Thunderstorm WarningLSXBrown47 min
Aug 18, 11:46 PM CDTSevere Thunderstorm WarningLSXPike44 min
Aug 19, 12:35 AM CDTSevere Thunderstorm WarningLSXGreene40 min

Nearby

Severe Thunderstorm Warnings in Illinois, 1999Every severe thunderstorm warning in 1999

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.