Alert archive / Illinois / Severe Thunderstorm Warnings in 1999
Severe Thunderstorm Warning 91, NWS St. Louis, MO
NWS St. Louis, MO issued this severe thunderstorm warning at May 17, 1999, 3:02 PM CDT for Clinton County, Washington County, Illinois. It was in force for 48 min. 3 reports 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
- May 17, 1999, 3:02 PM CDT (20:02 UTC)
- Expired
- May 17, 1999, 3:50 PM CDT
- In force
- 48 min
- Issued by
- NWS St. Louis, MO
- Area
- Whole counties
Counties Clinton County, IL, Washington County, IL
The radar
The St Louis radar (KLSX), 113 km from the middle of the area, began a volume at 20:02 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 |
|---|---|---|---|
| May 17, 3:10 PM CDT | Thunderstorm Wind 55 | Okawville, IL | |
| May 17, 3:15 PM CDT | Thunderstorm Wind 55 | Germantown, IL | |
| May 17, 3:25 PM CDT | Thunderstorm Wind 55 | Hoffman, 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 |
|---|---|---|---|
| May 17, 3:00 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
The nearest sounding before it
Lincoln, IL (KILX), launched 12:00Z, 8.0 hours before the alert went out and 199 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.
- Mixed-layer CAPE
- 8 J/kg
- Mixed-layer CIN
- -466 J/kg
- Mixed-layer LCL
- 1464 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- -19 m²/s²
- 0-3 km storm-relative helicity
- 100 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
999 WUUS1 KSTL 172004 RRA SVRSTL ILC027-189-172050- BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE ST LOUIS MO 302 PM CDT MON MAY 17 1999 THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... SOUTHERN CLINTON COUNTY IN SOUTHWESTERN ILLINOIS WASHINGTON COUNTY ILLINOIS IN SOUTHWESTERN ILLINOIS * UNTIL 350 PM CDT * AT 302 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM FAR WESTERN WASHINGTON COUNTY... MOVING NORTHEAST AT 35 MPH. * LOCATIONS THAT WILL BE AFFECTED... OKAWVILLE GERMANTOWN POSEY COVINGTON THE PRIMARY SEVERE WEATHER THREAT IS DAMAGING HAIL. LARGE HAIL CAN CAUSE EXTENSIVE PROPERTY DAMAGE AN SERIOUS INJURY TO PEOPLE CAUGHT OUTDOORS. MOVE INSIDE A STURDY BUILDING IMMEDIATELY. RP/MB
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
Special weather statement, May 17, 11:00 AM CDT, 4 hours 2 minutes before
ILZ058>060-064-065-069-070-074-079-095>102-MOZ009-010-018-019-026- 027-034>036-041-042-047>052-059>065-072>075-084-085-099-181300- SEVERE WEATHER OUTLOOK NATIONAL WEATHER SERVICE ST LOUIS MO 1100 AM CDT MON MAY 17 1999 THIS OUTLOOK COVERS THE COUNTY WARNING AREA OF THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN ST LOUIS. AREAS INCLUDED ARE PORTIONS OF NORTHEAST...CENTRAL...EAST CENTRAL AND SOUTHEAST MISSOURI AS WELL AS WEST CENTRAL AND SOUTHWEST ILLINOIS. THE AREA DESIGNATED EARLIER AS A SLIGHT RISK FOR SEVERE THUNDERSTORMS HAS BEEN SHIFTED SOUTHEAST SOMEWHAT AND NOW INCLUDES AN AREA EAST OF A LINE FROM SPRINGFIELD ILLINOIS TO ST LOUIS TO BRANSON MISSOURI. AREAS OF NORTHEASTERN MISSOURI HAVE BEEN EXCLUDED IN THIS OUTLOOK AREA. THOUGH THE CHANCE FOR SEVERE THUNDERSTORMS IS LIMITED...THE PROBABILITY OF HEAVY AND REPEATED THUNDERSTORMS TREKING ACROSS THE SAME AREA REMAINS A POSSIBILITY AND THEREFORE A FLASH FLOOD WATCH REMAINS IN EFFECT FOR TODAY FOR THE ENTIRE WARNING AREA. STORM SPOTTER GROUPS AND EMERGENCY MANAGERS SHOULD MONITOR WEATHER DEVELOPMENTS THROUGHOUT THE DAY FOR POSSIBLE SKYWARN ACTION...FOR FLOODING PROBLEMS NORTHWEST AND FOR SEVERE STORMS IN THE SOUTHEAST PORTION OF THE FORECAST AREA. PEDIGO
Special weather statement, May 17, 11:00 AM CDT, 4 hours 2 minutes before
ILZ058>060-064-065-069-070-074-079-095>102-MOZ009-010-018-019-026- 027-034>036-041-042-047>052-059>065-072>075-084-085-099-181300- SEVERE WEATHER OUTLOOK NATIONAL WEATHER SERVICE ST LOUIS MO 1100 AM CDT MON MAY 17 1999 THIS OUTLOOK COVERS THE COUNTY WARNING AREA OF THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN ST LOUIS. AREAS INCLUDED ARE PORTIONS OF NORTHEAST...CENTRAL...EAST CENTRAL AND SOUTHEAST MISSOURI AS WELL AS WEST CENTRAL AND SOUTHWEST ILLINOIS. THE AREA DESIGNATED EARLIER AS A SLIGHT RISK FOR SEVERE THUNDERSTORMS HAS BEEN SHIFTED SOUTHEAST SOMEWHAT AND NOW INCLUDES AN AREA EAST OF A LINE FROM SPRINGFIELD ILLINOIS TO ST LOUIS TO BRANSON MISSOURI. AREAS OF NORTHEASTERN MISSOURI HAVE BEEN EXCLUDED IN THIS OUTLOOK AREA. THOUGH THE CHANCE FOR SEVERE THUNDERSTORMS IS LIMITED...THE PROBABILITY OF HEAVY AND REPEATED THUNDERSTORMS TREKING ACROSS THE SAME AREA REMAINS A POSSIBILITY AND THEREFORE A FLASH FLOOD WATCH REMAINS IN EFFECT FOR TODAY FOR THE ENTIRE WARNING AREA. STORM SPOTTER GROUPS AND EMERGENCY MANAGERS SHOULD MONITOR WEATHER DEVELOPMENTS THROUGHOUT THE DAY FOR POSSIBLE SKYWARN ACTION...FOR FLOODING PROBLEMS NORTHWEST AND FOR SEVERE STORMS IN THE SOUTHEAST PORTION OF THE FORECAST AREA. PEDIGO
The office that day
Everything else NWS St. Louis, MO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 17, 2:43 AM CDT | Severe Thunderstorm Warning | LSX | Pike | 47 min |
| May 17, 2:25 PM CDT | Severe Thunderstorm Warning | LSX | Saint Clair | 35 min |
| May 17, 3:39 PM CDT | Severe Thunderstorm Warning | LSX | Marion | 46 min |
| May 17, 3:52 PM CDT | Severe Thunderstorm Warning | LSX | Fayette | 48 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.